roof framing - 400 Bad Request

roof framing - 400 Bad Request
Naval Education and
Training Command
March 1994
Training Manual
Builder 3 & 2, Volume 2
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must use the purchasing instructions on the inside cover.
Although the words “he,” “him,” and “his”
are used sparingly in this manual to enhance
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gender driven nor to affront or discriminate
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DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.
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1994 Edition Prepared by
BUCS (SCW) John Buza
This training manual (TRAMAN) and its associated nonresident training course
(NRTC) are two units of a self-study program that will enable you, the Builder, to
fulfill the requirements of your rating.
Designed for individual study and not formal classroom instruction, this
TRAMAN provides subject matter that relates directly to the occupational standards
of the Builder rating. The NRTC provides a way of satisfying the requirements for
completing the TRAMAN. The assignments in the NRTC are intended to emphasize
the key points in the TRAMAN.
Scope of revision—This TRAMAN contains new information on embarkation,
K-span buildings, and tile, expands discussion of roof truss systems and coverings,
and reorganize sections dealing with interior and exterior finishing. The entire
TRAMAN was reviewed for currency and updated as required.
This training manual and its separate nonresident training course were prepared
by the Naval Education and Training Program Management Support Activity,
Pensacola, Florida, for the Chief of Naval Education and Training. Technical
assistance was provided by the Third Naval Construction Brigade, Pearl Harbor,
Hawaii, and the Naval Construction Training Center, Gulfport, Mississippi.
1994 Edition
Stock Ordering Number
Published by
1. Light Floor and Wall Framing . . . . . . . . . . . . . . . . . .1-1
2. Roof Framing . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1
3. Roof Construction and Trim Carpentry . . . . . . . . . . . . . . . .3-1
4. Exterior Finish of Walls . . . . . . . . . . . . . . . . . . . . . .4-1
5. Interior Finish of Walls and Ceilings . . . . . . . . . . . . . . . . .5-1
6. Interior Finish of Floors, Stairs, Doors, and Trim . . . . . . . . . .6-1
7. Plastering, Stuccoing, and Ceramic Tile . . . . . . . . . . . . . . .7-1
8. Structural Coatings and Preservatives . . . . . . . . . . . . . . . . 8-1
9. Advanced Base Field Structures and Embarkation . . . . . . . . . .9-1
10. Heavy Construction . . . . . . . . . . . . . . . . . . . . . . .10-1
I. Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AI-1
II. References Used to Develop the TRAMAN . . . . . . . . . . . AII-1
INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INDEX-1
Builder 3&2, Volume 1, NAVEDTRA 12520, is a basic book that should be
mastered by those seeking advancement to Builder Third Class and Builder Second
Class. The major topics addressed in this book include construction administration
and safety; drawings and specifications; woodworking tools, materials and methods
of woodworking; fiber line, wire rope, and scaffolding; leveling and grading;
concrete; placing concrete; masonry; and planning, estimating, and scheduling.
Builder 3&2, Volume 2, NAVEDTRA 12521, continues where Volume 1 ends.
The topics covered in this volume include floor and wall construction; roof framing;
exterior and interior finishing; plastering, stuccoing, and ceramic tile; paints and
preservatives; advanced base field structures; and heavy construction.
In the normal sequence of construction events, the
in this area is critical as it is the real point of departure
for actual building activities.
floor and wall activities follow the completed
foundation work. In this chapter, we’ll examine
established methods of frame construction and discuss
in general how floor and wall framing members are
assembled. An explanation of subflooring installation,
exterior sheathing, interior partitions, and rough
openings for doors and windows is also given.
The box sill is usually used in platform construction.
It consists of a sill plate and header joist anchored to the
foundation wall. Floor joists are supported and held in
position by the box sill (fig. 1-1). Insulation material and
metal termite shields are placed under the sill if desired
or when specified. Sills are usually single, but double
sills are sometimes used.
this section, you should be able to describe sill
layout and installation.
Following construction of the foundation wall, the
sill is normally the first member laid out. The edge of
the sill is setback from the outside face of the foundation
a distance equal to the thickness of the exterior
sheathing. When laying out sills, remember the comers
should be halved together, but are often butted or
mitered. If splicing is necessary to obtain required
Framing of the structure begins after completion of
the foundation. The lowest member of the frame
structure resting on the foundation is the sill plate, often
called the mud sill. This sill provides a roiling base for
joists or studs resting directly over the foundation. Work
Figure 1-1.—Box-sill assembly.
Figure 1-2.—Anchor bolt layout.
length, you should halve the splice joint at least 2 feet
and bolt together.
Once the required length has been determined, the
next step is to lay out the locations of the anchor bolt
holes. Use the following steps:
Figure 1-4.—Installing termite shields.
the holes; that is, X equals the thickness of the
exterior sheathing.
After all the holes are marked, bore the holes. Each
should be about 1/4 inch larger than the diameter of the
bolts to allow some adjustment for slight inaccuracies
in the layout. As each section is bored, position that
section over the bolts.
1. Establish the building line points at each of the
corners of the foundation.
2. Pull a chalk line at these established points and
snap a line for the location of the sill.
3. Square the ends of the sill stock, (Stock received
at jobsites is not necessarily squared at both
When all sill sections are fitted, remove them from
the anchor bolts. Install sill sealer (insulation) as shown
in figure 1-3. The insulation compresses, filling the
irregularities in the foundation. It also stops drafts and
reduces heat loss. Also install a termite shield (fig. 1-4)
if specified. A termite shield should be at least 26-gauge
aluminum, copper, or galvanized sheet metal. The outer
edges should be slightly bent down. Replace the sills and
4. Place the sill on edge and mark the locations of
the anchor bolts.
5. Extend these marks with a square across the
width of the sill. The distance X in figure 1-2
shows how far from the edge of the sill to bore
Figure 1-3.—Installing sill sealer.
Figure 1-5.—Methods of sill fastening to foundations.
Figure 1-6.—Spacing of anchor bolts.
view A) and a minimum of 7 inches into reinforced
install the washers and nuts. As the nuts are tightened,
make sure the sills are properly aligned. Also, check the
distance from the edge of the foundation wall. The sill
must be level and straight. Low spots can be shimmied
with wooden wedges, but it is better to use grout or
concrete (view B). The length of the anchor bolt is found
in the specifications; the spacing and location of the
bolts are shown on the drawings. If this information is
not available, anchor bolt spacing should not exceed 6
feet on center (OC). Also, a bolt must be placed within
1 foot of the ends of each piece (as shown in fig. 1-6).
There are alternative ways to fasten sill plates to
Wood sills are fastened to masonry walls by
1/2-inch anchor bolts. These bolts, also known as j-bolts
because of their shape, should be embedded 15 inches
or more into the wall in unreinforced concrete (fig. 1-5,
foundations. Location and building codes will dictate
which to use. Always consult the job specifications
before proceeding with construction.
Figure 1-7.—Basic components of floor framing.
Figure 1-8.—Floor framing on sill plates with intermediate posts and built-up girders.
this section, you should be able to identify
Floor framing consists specifically of the posts,
girders, joists, and subfloor. When these are assembled,
as in figure 1-7, they form a level anchored platform for
the rest of the construction.
members used in floor construction, and the
construction methods used with subfloor and
Wood or steel posts and girders support floor joists
and the subfloor. Sizes depend on the loads carried. The
Wood posts are placed directly below wood girders.
As a general rule, the width of the wood post should be
equal to the width of the girder it supports. For example,
a 4-inch-wide girder requires a 4- by 4- or 4- by 6-inch
A wood post can be secured to a concrete pillar in
several ways. The post can be nailed to a pier block
secured to the top of a concrete pier; it can be placed
over a previously inserted 1/2-inch steel dowel in the
concrete; or, it can be placed into a metal base set into
the concrete pier at the time of the pour. When using
the dowel method, make sure the dowel extends at least
3 inches into the concrete and the post, as shown in
figure 1-9. A metal base embedded in the concrete
(fig. 1-10) is the preferred method since nothing else is
needed to secure the base.
Figure 1-9.—Post fastened using dowel method.
As with the bottom of the post, the top must also be
secured to the girder. This can be done using angle iron
brackets or metal plates. Figure 1-11 shows two metal
post caps used with posts and girders, either nailed or
bolted to the girders.
Figure 1-10.—Metal base plates for wood posts.
dimensions and locations are shown on the foundation
plan. When required, posts give central support to the
long span of girders. Also, girders can be used to support
other girders. There should be at least 18 inches
clearance between the bottoms of the floor joists and the
ground and at least 12 inches between the bottom of the
girder and the ground (fig. 1-8).
Figure 1-11.—Metal post caps.
The base of the steel post is bolted to the top of the pier,
as shown in figure 1-12. The post can also be bolted to
anchor bolts inserted in the slab prior to pouring.
Girders are classified as bearing and nonbearing
according to the amount and type of load supported.
Bearing girders must support a wall framed directly
above, as well as the live load and dead load of the floor.
Nonbearing girders support just the dead and live loads
of the floor system directly above. The dead load is the
weight of the material used for the floor unit itself. The
live load is the weight created by people, furniture,
appliances, and so forth.
Figure 1-12.—Bolting of steel column.
Steel pipe columns are often used in wood-frame
construction, with both wood and steel girders. When
using wood girders, secure the post to the girder with
lag bolts. For steel girders, machine bolts are required.
Wood girders may be a single piece of timber, or
they may be laminated (that is, built up) of more than
one plank. The built-up girder in figure 1-13, for
example, consists of three 2- by 12-inch planks. The
Figure 1-13.—Built-up girder.
Figure 1-14.—Spaced wood girders.
or steel, make sure it aligns from end to end and side to
side. Also make sure the length of the bearing post under
the girder is correct to ensure the girder is properly
joints between the planks are staggered. In framing, a
built-up girder is placed so that the joints on the outside
of the girder fall directly over a post. Three 16-penny
(16d) nails are driven at the ends of the planks, and other
nails are staggered 32 inches OC. As shown in figure
1-13, the top of the girder is flush with the top sill plate.
When space is required for heat ducts in a partition
supported on a girder, a spaced wood girder, such as that
shown in figure 1-14, is sometimes necessary. Solid
blocking is used at intervals between the two members.
A single-post support for a spaced girder usually
requires a bolster, preferably metal, with a sufficient
span to support the two members.
Posts must be cut to length and set up before the
girders can be installed. The upper surface of the girder
may be in line with the foundation plate sill, or the girder
ends may rest on top of the walls. Long girders must be
The ends of a girder often rest in pockets prepared
in a concrete wall (fig. 1-13). Here, the girder ends must
bear at least 4 inches on the wall, and the pocket should
be large enough to provide a 1/2-inch air space around
the sides and end of the girder. To protect against
termites, treat the ends of the girder with a preservative.
As a further precaution, line the pockets with metal.
S-beams (standard) or W-beams (wide flange), both
shown in figure 1-15, are most often used as girders in
wood-framed construction. Whether the beam is wood
Figure 1-15—Types of steel beams.
Figure 1-17.—Lapped joists.
Figure 1-16.—Header joist.
rolling or tipping. They also help support the wall above
and fill in the spaces between the common joists.
placed in sections. Solid girders must be measured and
cut so that the ends fall over the center of a post. Built-up
girders should be placed so their outside joints fall over
the posts (fig. 1-13).
Joists are often lapped over a girder running down
the center of a building. The lapped ends of the joists
may also be supported by an interior foundation or
framed wall. It is standard procedure to lap joists the full
width of the girder or wall. The minimum lap should be
4 inches. Figure 1-17 shows lapped joists resting on a
steel girder. A 2- by 4-inch plate has been bolted to the
top of a steel beam. The joists are toenailed into the plate.
Solid blocking may be installed between the lapped ends
after all the joists have been nailed down. Another
system is to put in the blocks at the time the joists are
In platform framing, one end of the floor joist
rests directly on the sill plate of the exterior
foundation wall or on the top plate of a framed outside
wall. The bearing should be at least 1 1/2 inches. The
opposite end of the joist laps over or butts into an
interior girder or wall. The size of joist material (2 by
6, 2 by 10, 2 by 12, and so forth) must be chosen with
consideration for the span and the amount of load to
be carried. The foundation plan usually specifies the
joist size, the spacing between joists, and what
direction the joists should travel.
The usual spacing of floor joists is 16 inches OC.
Floor joists are supported and held in position over
exterior walls by header joists or by solid blocking
between the joists. The header-joist system is used most
Joists should be doubled under partitions running in
the same direction as the joists. Some walls have water
pipes, vent stacks, or heating ducts coming up from the
basement or the floor below. Place bridging between
double joists to allow space for these purposes
(fig. 1-18).
Header joists run along the outside walls. Three 16d
nails are driven through the header joists into the ends
of the common joists, as shown in figure 1-16. The
header and joists are toenailed to the sill with 16d nails.
The header joists prevent the common joists from
Cantilevered joists are used when a floor or balcony
of a building projects past the wall below, as shown in
figure 1-19. A header piece is nailed to the ends of the
Figure 1-18.—Double joists.
Figure 1-19.—Cantilevered joists.
Figure 1-20.—Framing for cantilevered joists.
joists. When regular floor joists run parallel to the
intended overhang, the inside ends of the cantilevered
joists are fastened to a pair of double joists (fig. 1-20).
Nailing should be through the first regular joist into the
ends of the cantilevered joists. Framing anchors are
strongly recommended and often required by the
specifications. A header piece is also nailed to the
outside ends of the cantilevered joists.
Figure 1-21.—Butting joists over a girder.
Butted over a Girder
Joist ends can also be butted (rather than lapped)
over a girder. The joists should then be cleated together
with a metal plate or wooden cleat, as shown in
Figure 1-22.—Butting Joists against a girder.
Figure 1-24.—Joists supported on steel plates.
and difficult to handle. Therefore, two or more shorter
joists are usually used. The ends of these joists are
supported by lapping or butting them over a girder,
butting them against a girder, or lapping them over a
Supported by a Steel Beam
Figure 1-23.—Joists supported by steel beams.
Wood joists are often supported by a steel beam
rather than a wood girder. The joists may rest on
top of the steel beam (fig. 1-23, view A), or they
may be butted (and notched to fit) against the sides
of the beam (view B). If the joists rest on top of a
steel beam, a plate is fastened to the beam and the
joists are toenailed into the plate. When joists are
notched to fit against the sides of the beam,
allowance must be made for joist shrinkage while
the steel beams remain the same size. For average
work with a 2- by 10-inch joist, an allowance of 3/8
inch above the top flange of the steel girder or beam
is usually sufficient.
figure 1-21. These can be left out if the line of panels
from the plywood subfloor straddles the butt joints.
Butted against a Girder
Butting joists against (rather than over) a girder
allows more headroom below the girder. When it is
necessary for the underside of the girder to be
flush with the joists to provide an unbroken ceiling
surface, the joists should be supported with joist
hangers (fig. 1-22).
Another method of attaching butted joists to a
steel girder is shown in figure 1-24. A 3/8-inch
space is shown above the beam to allow for
shrinkage. Notching the joists so they rest on the
lower flange of an S-beam is not recommended; the
flange surface does not provide sufficient bearing
surface. A wide plate may be bolted or welded to
the bottom of the S-beams to provide better
support. Wooden blocks may be placed at the
bottoms of the joists to help keep them in position.
Wide-flanged beams, however, do provide
sufficient support surface for this method of
Blocking between Joists
Another system of providing exterior support to
joists is to place solid blocking between the outside ends
of the joists. In this way, the ends of the joists have more
bearing on the outside walls.
Interior Support
Floor joists usually run across the full width of the
building. However, extremely long joists are expensive
Figure 1-25.—Joists supported by S-beam using wooden blocks.
construction. Figure 1-25 shows the lapped (view A) and
butt (view B) methods of framing over girders.
Figure 1-26.—Wood cross bridging.
Bridging between Joists
Floor plans or specifications usually call for
bridging between joists. Bridging holds the joists in line
and helps distribute the load carried by the floor unit. It
is usually required when the joist spans are more than 8
feet. Joists spanning between 8 and 15 feet need one row
of bridging at the center of the span. For longer spans,
two rows of bridging spaced 6 feet apart are required.
end with 6d or 8d nails. Pieces are usually precut on a
radial-arm saw. Nails are started at each end before the
cross bridging is placed between the joists. The usual
procedure is to fasten only the top end of the cross
bridging. The nails at the bottom end are not driven in
until the subfloor has been placed. Otherwise the joist
could be pushed out of line when the bridging is nailed
C R O S S B R I D G I N G . — Also known as
herringbone bridging, cross bridging usually consists of
1- by 3-inch or 2- by 3-inch wood. It is installed as
shown in figure 1-26. Cross bridging is toenailed at each
An efficient method for initial placement of cross
bridging is shown in figure 1-26. In step 1, snap a chalk
line where the bridging is to be nailed between the joists.
In step 2, moving in one direction, stagger and nail the
Figure 1-27.—Metal cross bridging.
tops of the bridging. Instep 3, reverse direction and nail
tops of the opposite pieces into place.
Another approved system of cross bridging uses
metal pieces instead of wood and requires no nails. The
pieces are available for 12-, 16-, and 24-inch joist
spacing (fig. 1-27, view A). You can see how to install
this type of cross bridging in views B, C, and D. In view
B, strike the flat end of the lower flange, driving the
flange close to the top of the joist. In view C, push the
lower end of the bridging against the opposite joist. In
view D, drive the lower flange into the joist.
Figure 1-28.—Solid bridging.
SOLID BRIDGING.— Also known as solid
blocking, solid bridging (fig. 1-28) serves the same
purpose as cross bridging. This method is preferred by
many Builders to cross bridging. The pieces are cut from
lumber the same width as the joist material. They can be
installed in a straight line by toenailing or staggering. If
staggered the blocks can be nailed from both ends,
resulting in a faster nailing operation. Straight lines of
blocking may be required every 4 feet OC to provide a
nailing base for a plywood subfloor.
be nailed. As we mentioned earlier, floor joists are
usually placed 16 inches OC.
For joists resting directly on foundation walls,
layout marks may be placed on the sill plates or the
header joists. Lines must also be marked on top of the
girders or walls over which the joists lap. If framed walls
are below the floor unit, the joists are laid out on top of
the double plate. The floor layout should also show
where any joists are to be doubled. Double joists are
required where partitions resting on the floor run in the
same direction as the floor joists. Floor openings for
stairwells must also be marked.
Placing Floor Joists
Before floor joists are placed, the sill plates and
girders must be marked to show where the joists are to
Figure 1-29.—Floor joists layout.
Figure 1-30.—Comp1ete layout for floor joists.
Joists should be laid out so that the edges of
standard-size subfloor panels break over the centers of
the joists (see insert, fig. 1-29). This layout eliminates
additional cutting of panels when they are being fitted
and nailed into place. One method of laying out joists
this way is to mark the first joists 15 1/4 inches from the
edge of the building. From then on, the layout is 16
inches OC. A layout for the entire floor is shown in
figure 1-30.
Most of the framing members should be precut
before construction begins. The joists should all be
trimmed to their proper lengths. Cross bridging and
Figure 1-31.—Steps in framing a floor opening.
of strength in the area of the opening. You need to frame
solid blocks should be cut to fit between the joists having
a common spacing. The distance between joists is
usually 14 1/2 inches for joists spaced 16 inches OC.
Blocking for the odd spaces is cut afterwards.
the opening in a way that restores this strength. The
procedure is shown in figure 1-31. Refer to the figure as
you study the following steps:
1. Measure and mark the positions of the trimmers
on the outside wall and interior wall or girder.
Framing Floor Openings
Floor openings, where stairs rise to the floor or large
duct work passes through, require special framing.
When the joists are cut for such openings, there is a loss
2. Position and fasten the inside trimmers and mark
the position of the double headers.
Figure 1-32.—Types of framing anchors.
board for the crown. Some crowns are too large and
cannot be turned up for use as a joist.
3. Place the outside pieces between the inside
trimmers. Drive three 16d nails through the
trimmers into the headers. Mark the position of
the tail joists on the headers (the tail joists should
follow the regular joist layout).
4. Fasten the tail joists to the outside headers with
three 16d nails driven through the headers into
the ends of the tail joists.
The subfloor, also known as rough flooring, is
nailed to the top of the floor frame. It strengthens the
entire floor unit and serves as a base for the finish floor.
The walls of the building are laid out, framed, and raised
into place on top of the subfloor.
5. Double the header. Drive three 16d nails through
the trimmer joists into the ends of the doubled
header pieces. Nail the doubled header pieces to
each other with 16d nails staggered 16 inches
Panel products, such as plywood, are used for
subflooring. Plywood is less labor intensive than board
6. Double the trimmer joists and fasten them
together with 16d nails staggered 16 inches OC.
Plywood is the oldest type of panel product. It is still
the most widely used subfloor material in residential and
other light-framed construction. Other types of material
available for use as subflooring include nonveneered
(reconstituted wood) panels, such as structural
particleboard, waferboard, oriented strandboard, and
A pair of joists, called trimmers, is placed at each
side of the opening. These trimmers support the headers.
The headers should be doubled if the span is more than
4 feet. Nails supporting the ends of the headers are
driven through the trimmer joists into the ends of the
header pieces. Tail joists (cripple joists) run from the
header to a supporting wall or girder. Nails are driven
through the header into the ends of the tail joist. Various
metal anchors, such as those shown in figure 1-32, are
also used to strengthen framed floor openings.
Plywood is available in many grades to meet abroad
range of end uses. All interior grades are also available
with fully waterproof adhesive identical with that used
in exterior plywood. This type is useful where prolonged
moisture is a hazard. Examples are underlayments,
subfloors adjacent to plumbing fixtures, and roof
sheathing that may be exposed for long periods during
construction. Under normal conditions and for
sheathing used on walls, standard sheathing grades are
Most joists have a crown (a bow shape) on one side.
Each joist should be sighted before being nailed in place
to make certain the crown is turned up. The joist will
later settle from the weight of the floor and straighten
out. Caution should be exercised when sighting the
Plywood suitable for the subfloor, such as standard
sheathing, structural I and II, and C-C exterior grades,
has a panel identification index marking on each sheet.
Figure 1-33.—Typical exterior wall.
These markings indicate the allowance spacing of
rafters and floor joists for the various thicknesses when
this section, you should be able to identify wall
framing members and explain layout and
installation procedures for these members in
building construction.
the plywood is used as roof sheathing or subfloor. For
example, an index mark of 32/16 indicates the plywood
panel is suitable for a maximum spacing of 32 inches
for rafters and 16 inches for floor joists. Thus, no
problem of strength differences between species is
involved, as the correct identification is shown for each
Wall construction begins after the subfloor has been
nailed in place, The wall system of a wood-framed
buildlng consists of exterior (outside) and interior
(inside) walls. The typical exterior wall has door and
window openings, as shown in figure 1-33. Interior
walls, usually referred to as “partitions,” divide the
inside area into separate rooms. Some interior walls
have door openings or archways.
Plywood should be installed with the grain of the
outer plies at right angles to the joists. Panels should be
staggered so that end joints in adjacent panels break over
different joists. The nailing schedule for most types of
subfloor panels calls for 6d common nails for materials
Partitions are either bearing or nonbearing. Bearing
partitions support the ends of the floor joists or ceiling
joists. Nonbearing partitions run in the same direction
as the joists and therefore carry little weight from the
floor or ceiling above.
up to 7/8 inch thick and for 8d nails for heavier panels
up to 1 1/8 inches thick. Deformed-shank nails are
strongly recommended. They are usually spaced 6
inches OC along the edges of the panel and 10 inches
OC over intermediate joists.
Traditionally, 2-by 4-inch structural lumber is used
for the framed walls of one-story buildings, although the
use of heavier structural lumber is specified at certain
locations for particular projects. Multistory buildings,
For the best performance, do not lay up plywood
with tight joints, whether interior or exterior. Allow for
expansion if moisture should enter the joints.
Figure 1-34.—Corner posts.
for example, require heavier structural lumber. This
requirement is specific to the lower levels in order to
support the weight of the floors above.
Corner Posts
Corner posts are constructed wherever a wall ties
into another wall. Outside comers are at the ends of a
wall. Inside corners occur where a partition ties into a
wall at some point between the ends of the wall.
A wood-framed wall consists of structural parts
referred to as “wall components” or “framing
members.” The components (shown in fig. 1-33)
typically include studs, plates, headers, trimmers,
cripples, sills, corner posts, and diagonal braces. Each
component is essential to the integrity of the total wall
Three typical designs for corner assemblies are
shown in figure 1-34. View A shows outside corner
construction using only three studs. View B shows
outside corner construction using two studs with short
blocks between them at the center and ends. A third
full-length stud can be used instead of blocks. View C
shows inside corner construction using a block laid flat.
A full-length stud can be used instead of a block. Note
that all corner assemblies should be constructed from
straight stud material and should be well nailed. When
framing corners, you can use full-length studs or short
Studs are upright (vertical) framing members
running between the top and bottom plates. Studs are
usually spaced 16 inches OC, but job specifications
sometimes call for 12-inch and 24-inch OC stud
Rough Door and Window Openings
A rough opening must be framed into a wall
wherever a door or window is planned. The dimensions
of the rough opening must allow for the final frame and
for the required clearance around the frame.
The plate at the bottom of a wall is the soleplate, or
bottom plate. The plate at the top of the wall is the top
plate. A double top plate is normally used. It strengthens
the upper section of the wall and helps carry the weight
of the joists and roof rafters. Since top and bottom plates
are nailed into all the vertical wall members, they serve
to tie the entire wall together.
Figure 1-35 shows details of rough openings for
doors and windows in wood-frame construction. The
rough opening for atypical door is framed with a header,
Figure 1-35.—Rough frame openings for doors and windows.
trimmer studs, and, in some cases, top cripple studs. The
rough opening for a typical window includes the same
members as for a dear, plus a rough window sill and
bottom cripples.
opening and by how much weight is bearing down from
the floor above.
The tops of all door and window openings in all
walls are usually in line with each other. Therefore, all
headers are usually the same height from the floor. The
standard height of walls in most wind-framed buildings
is either 8 feet 3/4 inch or 8 feet 1 inch from the subfloor
to the ceiling joists. The standard height of the doors is
6 feet 8 inches.
A header is placed at the top of a rough opening. It
must be strong enough to carry the weight bearing down
on that section of the wall. The header is supported by
trimmer studs fitting between the soleplate and the
bottom of the header. The trimmer studs are nailed into
the regular studs at each side of the header. Nails are also
driven through the regular studs into the ends of the
Cripple studs are nailed between the header and the
double top plate of a door opening. These help carry the
weight from the top plate to the header. The cripple studs
are generally spaced 16 inches OC.
The header maybe either solid or built up of two 2
by 4 pieces with a 1/2-inch spacer. The spacer is needed
to bring the width of the header to 3 1/2 inches. This is
the actual width of a nominal 2 by 4 stud wall. A built-up
header is as strong as or stronger than a solid piece.
A rough window sill is added to the bottom of a
rough window opening. The sill provides support for the
finished window and frame to be placed in the wall. The
distance between the sill and the header is determined
by the dimensions of the window, the window frame,
and the necessary clearances at the top and bottom of
the frame. Cripple studs, spaced 16 inches OC, are
The type and size of header is shown in the
blueprints. Header size is determined by the width of the
Figure 1-36.—Types of bracing.
nailed between the sill and soleplate. Additional cripple
studs may be placed under each end of the sill.
requirement is an outside wall covered with structural
sheathing nailed according to building specifications.
This type of wall does not require bracing.
Diagonal bracing is most effective when installed at
a 45° to 60° angle. You can do this after the wall has
been squared and still lying on the subfloor. The most
widely used bracing system is the 1 by 4 let-in type, as
shown in figure 1-36. The studs are notched so that the
1 by 4 piece is flush with the surface of the studs.
Diagonal bracing is necessary for the lateral
strength of a wall. In all exterior walls and main interior
partitions, bracing should be placed at both ends (where
possible) and at 25-foot intervals. An exception to this
Figure 1-37.—Fire blocking.
Cut-in bracing (fig. 1-36) is another type of diagonal
bracing. It usually consists of 2 by 4s cut at an angle and
toenailed between studs at a diagonal from the top of a
corner post down to the soleplate.
It is not necessary to nail fire stops at the midpoint
of the wall. They can be positioned to provide additional
backing for nailing the edges of drywall or plywood.
Diagonal sheathing (fg. 1-36) is the strongest type
of diagonal bracing. Each board acts as a brace for the
wall. When plywood or other panel sheathing is used,
other methods of bracing maybe omitted.
All major components of a wall should be cut before
assembly. By reading the blueprints, you can determine
the number of pieces and lengths of all components. The
different parts of the wall are then assembled. Any hard,
level surface can be used for assembly. After completing
nailing, raise the walls in place for securing.
Fire stops
Most local building codes require fire stops (also
known as fire blocks) in walls over 8 foot 1 inch high.
Fire stops slow down fire travel inside walls. They can
be nailed between the studs before or after the wall is
raised. Fire stops can be nailed in a straight line or
staggered for easier nailing. Figure 1-37 shows a section
of a framed wall with fire stops.
Two layout procedures are used in wall layout:
horizontal plate and vertical layout. In horizontal plate
layout, the location of the wall is determined from the
dimensions found in the floor plan of the blueprints. For
vertical layout, the dimension can be found in the
sectional views of the building’s blueprints.
Figure 1-38.—Layout and cutting of plates.
Figure 1-39.—Marking inside and outside corners.
Figure 1-40.—First exterior wall stud layout.
Figure 1-41.—Second exterior wall stud layout.
A procedure for marking outside and inside comers
for stud-and-block corner post construction is shown in
figure 1-39. For laying out studs for the first exterior
wall, see figure 1-40. In figure 1-40, the plates are
marked for the first stud from a corner to be placed 15
1/4 inches from the end of the turner. Studs after the first
stud follow 16 inches OC layout. This ensures the edges
of standard-size panels used for sheathing or wallboard
fall on the centers of the studs. Cripples are laid out to
follow the layout of the studs.
A procedure for laying out studs for the second
exterior wall is shown in figure 1-41. The plates are
Horizontal Plate Layout
After all the lines are snapped, the wall plates are
cut and tacked next to the lines (fig. 1-38). The plates
are then marked off for corner posts and regular studs,
as well as for the studs, trimmers, and cripples for the
rough openings. All framing members must be clearly
marked on the plates. This allows for efficient and
error-free framing. Figure 1-37 shows a wall with
framing members nailed in place according to layout
Figure 1-42.—Starting measurement for interior wall.
frame. Some blueprint door and window schedules give
the rough opening dimensions, simplifying the layout.
marked for the first stud to be placed 15 1/4 inches from
the outside edge of the panel thickness on the first wall.
This layout allows the corner of the first panel on the
second wall to lineup with the edge of the first panel on
the second wall. Also, the opposite edge of the panel on
the second wall will break on the center of a stud.
A rough opening for a metal window often requires
a 1/2-inch clearance around the entire frame. When the
measurements are not given in the window schedule,
take them from the manufacturer’s installation
instructions supplied with the windows.
A procedure for laying out studs for interior walls
(partitions) is shown in figure 1-42. If panels are placed
on the exterior wall first, the wall plates for the interior
wall are marked for the first stud to be placed 15 1/4
inches from the edge of the panel thickness on the
exterior wall. If panels are to be placed on the interior
wall, the wall plates of the interior wall are marked for
the first stud to be placed 15 1/4 inches from the
unpaneled exterior wall.
A completely laid out bottom plate includes
markings for corner posts, rough openings, studs, and
cripples. The corner posts are laid out first. Next, the
16-inch marks for the studs and cripples are marked, and
then the marks for the rough openings are made.
Some Builders prefer to layout the rough openings
before the studs and cripples are marked. There is,
however, an advantage to laying out the 16-inch OC
marks first. Studs and trimmers framing a door and
window often fall very close to a 16-inch OC stud mark
Slightly shifting the position of the rough opening may
eliminate an unnecessary stud from the wall frame.
If drywall or other interior finish panels are to be
nailed to an adjoining wall (fig. 1-42, view A), you must
measure 15 1/4 inches plus the thickness of the material.
When panels are to be nailed on a wall first (view B),
measure and mark the 15 1/4 inches from the front
surface of the bottom plate. These procedures ensure
stud alignment remains accurate throughout the nailing
Vertical Layout
Vertical layout is the procedure for calculating the
lengths of the different vertical members of a
wood-framed wall. This makes it possible to precut all
studs, trimmers, and cripples required for a building.
Rough openings for doors and windows must also
be marked on the wall plates. The rough opening
dimensions for a window (fig, 1-43, view A) or wood
door (view B) are calculated based on the window or
door width, the thickness of the finish frame, and
1/2-inch clearance for shim materials at the sides of the
Some blueprints contain section views giving the
exact rough heights of walls. The rough height is the
distance from the subfloor to the bottom of the ceiling
Figure 1-43.—Measurements for windows and doors.
The distance from the bottom to the top of a rough
joists. The rough height to the top of the door (the
distance from the subfloor to the bottom of the door
header) may also be noted on the section drawing. In
addition, it may be given in the column for rough
opening measurements on the door schedule. The rough
height to the top of the door establishes the measurement
for the rough height to the top of the window, as window
headers are usually in line with door headers.
window opening can be found by measuring down from
the bottom of the window header using dimensions
provided in the rough opening column of the window
Many Builders prefer to frame the door and window
openings before assembling the wall. View A of
Figure 1-44.—Framing typical door and window openings.
and bottom plates at a distance slightly greater than the
length of the studs. Position the corners and openings
between the plates according to the plate layout.
Place studs in position with the crown side up. Nail
the plates into the studs, cripples, and trimmers. On
long walls, the breaks in the plates should occur
over a stud or cripple.
figure 1-44 shows typical door framing; view B shows
typical window framing. After stud layout, cripple studs
are laid out (usually 16 inches OC) and nailed between
the header and top plate and rough window sill and
soleplate. It is a good practice to place a cripple stud
under each end of a sill.
Placing the Double Top Plate
After the corners and openings for doors and
windows have been made up, the entire wall can be
nailed together .on the subfloor (fig. 1-45). Place top
The double top plate (fig. 1-46) can be placed while
the wall is still on the subfloor or after all the walls have
Figure 1-45.—Assembly of wall components.
Figure 1-46.—Double top plate.
Figure 1-48.—Let-in diagional brace.
After a wall has been raised, its bottom plates must
be nailed securely to the floor. Where the wall rests on
a wood subfloor and joists, 16d nails should be driven
through the bottom plate and into the floor joists below
the wall.
Figure 1-47.—Squaring a wall.
been raised. The topmost plates are nailed so that they
overlap the plates below at all corners. This helps to tie
the walls together. All ends are fastened with two 16d
nails. Between the ends, 16d nails are staggered 16
inches OC. The butt joints between the topmost plates
should be at least 4 feet from any butt joint between the
plates below them.
Plumbing and Aligning
Accurate plumbing of the comers is possible only
after all the walls are up. Most framing materials are not
perfectly straight; walls should never be plumbed by
applying a hand level directly to an end stud. Always
use a straightedge along with the level, as shown in
figure 1-49, view A. The straightedge can be a piece
ripped out of plywood or a straight piece of 2 by 4
lumber. Blocks 3/4 inch thick are nailed to each end. The
blocks make it possible to accurately plumb the wall
from the bottom plate to the top plate.
Plumbing corners requires two persons working
together-one working the bottom area of the brace and
the other watching the level. The bottom end of the brace
is renailed when the level shows a plumb wall.
The tops of the walls (fig. 1-49, view B) are
straightened (aligned or lined up) after all the corners
have been plumbed. Prior to nailing the floor or ceiling
joists to the tops of the walls, make sure the walls are
aligned. Here’s how: Fasten a string from the top plate
atone corner of the wall to the top plate at another corner
of the wall. You then cut three small blocks from 1 by 2
lumber, Place one block under each end of the string so
that the line is clear of the wall.
The third block is used as a gauge to check the wall
at 6- or 8-foot intervals. At each checkpoint, a temporary
brace is fastened to a wall stud.
When fastening the temporary brace to the wall
stud, adjust the wall so that the string is barely touching
the gauge block. Nail the other end of the brace to a short
2 by 4 block fastened to the subfloor. These temporary
Squaring Walls and Placing Braces
A completely framed wall is often squared while it
is still lying on the subfloor. In this way, bracing,
plywood, or other exterior wall covering can be nailed
before the wall is raised. When diagonal measurements
are equal, the wall is square. Figure 1-47 shows
examples of unsquared and squared walls.
A let-in diagonal brace maybe placed while the wall
is still on the subfloor. Lay out and snap a line on the
studs to show the location of the brace (fig. 1-48). The
studs are then notched for the brace. Tack the brace to
the studs while the wall is still lying on the subfloor.
Tacking instead of nailing allows for some adjustment
after the wall is raised. After any necessary adjustment
is made, the nails can be securely driven in.
Most walls can be raised by hand if enough help is
available. It is advisable to have one person for every 10
feet of wall for the lifting operation.
The order in which walls are framed and raised may
vary from job to job. Generally, the longer exterior walls
are raised first. The shorter exterior walls are then raised,
and the comers are nailed together. The order of framing
interior partitions depends on the floor layout.
Figure 1-49.—Plumbing and aligning corners and walls.
braces are not removed until the framing and sheathing
for the entire building have been completed.
Wall sheathing is the material used for the exterior
covering of the outside walls. In the past, nominal
1-inch-thick boards were nailed to the wall horizontally
or at a 45° angle for sheathing. Today, plywood and other
types of panel products (waferboard, oriented
strandboard, compositeboard) are usually used for
sheathing. Plywood and nonveneered panels can be
applied much quicker than boards. They add
considerable strength to a building and often eliminate
the need for diagonal bracing.
Generally, wall sheathing does not include the
finished surface of a wall, Siding, shingles, stucco, or
brick veneer are placed over the sheathing to finish the
wall. Exterior finish materials are discussed later in this
Framing over Concrete Slabs
Often, the ground floor of a wood-framed building
is a concrete slab. In this case, the bottom plates of the
walls must be either bolted to the slab or nailed to the
slab with a powder-actuated driver. If bolts are used,
they must be accurately set into the slab at the time of
the concrete pour. Holes for the bolts are laid out and
drilled in the bottom plate when the wall is framed.
When the wall is raised, it is slipped over the bolts and
secured with washers and nuts.
Occasionally, on small projects, the soleplate is
bolted or fastened down first. The top plate is nailed to
the studs, and the wall is lifted into position. The bottom
ends of the studs are toenailed into the plate. The rest of
the framing procedure is the same as for walls nailed on
top of a subfloor.
Plywood is the most widely used sheathing
material. Plywood panels usually applied to exterior
Figure 1-50.-Plywood sheathing.
walls range in size from 4 by 8 feet to 4 by 12 feet with
thicknesses from 5/16 inch to 3/4 inch. The panels may
be placed with the grain running vertically or
horizontally (fig. 1-50). Specifications may require
blocking along the long edges of horizontally placed
Typical nailing specifications require 6d nails with
panels 1/2 inch or less in thickness and 8d nails for
panels more than 1/2 inch thick. The nails should be
spaced 6 inches apart along the edges of the panels and
12 inches apart at the intermediate studs.
When nailing the panels, leave a 1/8-inch gap
between the horizontal edges of the panels and a
1/16-inch gap between the vertical edges. These gaps
allow for expansion caused by moisture and prevent
panels from buckling.
In larger wood-framed buildings, plywood is often
nailed to some of the main interior partitions. The result
is called a shear wall and adds considerable strength to
the entire building.
Plywood sheathing can be applied when the squared
wall is still lying on the subfloor. However, problems
can occur after the wall is raised if the floor is not
perfectly straight and level. For this reason, some
Builders prefer to place the plywood after the entire
building has been framed.
Figure 1-51.—Typical metal stud construction.
nonveneered (reconstituted wood) panels. Panels made
of waferboard, oriented strandboard, and compositeboard have been approved by most local building codes
for use as wall sheathing. Like plywood, these panels
resist racking, so no comer bracing is necessary in
normal construction. However, where maximum shear
strength is required, conventional veneered plywood
panels are still recommended.
The application of nonveneered wall sheathing is
similar to that for plywood. Nailing schedules usually
call for 6d common nails spaced 6 inches OC above the
panel edges, and 12 inches OC when nailed into the
intermediate studs. Nonveneered panels are usually
applied with the long edge of the panel in a vertical
Nonveneered Panels
Although plywood is the most commonly used
material for wall sheathing, specs sometimes call for
Metal is an alternative to wood framing. Many
buildings are framed entirely of metal, whereas some
Figure 1-52.—Chase wall construction.
dry rot. Also, when combined with proper covering
material, they have a high fire-resistance rating.
A variety of systems have been developed by
manufacturers to meet various requirements of
attachment, sound control, and fire resistance. Many of
the systems are designed for ease in erection, yet they
are still remountable for revising room arrangements.
The framing members are assembled with power
screwdrivers and using self-drilling, self-tapping
screws. The floor assembly is fastened to the foundation
or concrete slab with studs (special nails) driven through
the stud track (runner) by a powder-actuated stud driver.
The plywood subfloor is installed over the metal floor
framing system with self-drilling, self-tapping screws
and structural adhesive. Wall sections are assembled at
the jobsite or delivered as preassembled panels from an
off-site prefabrication shop. Conventional sheathing is
attached to the framework with self-tapping screws.
Door frames for both the interior partitions and
exterior walls are integral with the system. They are
preprinted and may come complete with necessary
buildings are framed in a combination of metal and
The metal framing members generally used are
cold-formed steel, electrogalvanized to resist corrosion.
Thicknesses range from 18 gauge to 25 gauge, the latter
being most common. Most metal studs have notches at
each end and knockouts located about 24 inches OC (fig.
1-51) to facilitate pipe and conduit installation. the size
of the knockout, not the size of the stud, determines the
maximum size of pipe or other material that can be
passed through horizontally.
Chase (or double stud) walls (fig. 1-52) are often
used when large pipes, ducts, or other items must pass
vertically or horizontally in the walls. Studs are
generally available in thicknesses of 1 5/8, 2 1/2, 3 5/8,
4, and 6 inches. The metal runners used are also
25-gauge (or specified gauge) steel or aluminum, sized
to complement the studs. Both products have features
advantageous to light-frame construction. The metal
studs and runners do not shrink swell, twist, or warp.
Termites cannot affect them, nor are they susceptible to
Figure 1-53.—Wood blocking for celling or wall-mounted fixtures.
Figure 1-54.—Standard corner bead.
Figure 1-56.—Casing and trim beads.
hinges, locks, rubber stops, and weather stripping. The
windows are also integral to the system, prefabricated
and painted. These units may include interior and
exterior trim designed to accept 1/2-inch wallboard and
1/2-inch sheathing plus siding on the outside.
Plumbing is installed in prepunched stud webs.
Wiring is passed through insulated grommets inserted
in the prepunched webs of the studs and plates. Wall and
ceiling fixtures are mounted by attaching wood blocking
spaced between the flanges of the wall studs or trusses
Figure 1-55.—Multiflex tape bead.
(fig. 1-53). Friction-tight insulation is installed by
placing the batts (bundles of insulating material)
between the studs on the exterior walls. Studs are spaced
12, 16, or 24 inches OC as specified in the blueprints.
or 5/8-inch single-layer wallboard; 1 1/4 inches by
1 1/4 inches for two-layer wallboard application. It is
available in 10-foot lengths.
Multiflex tape bead consists of two continuous
metal strips on the undersurface of 2 1/8-inch-wide
reinforcing tape (fig. 1-55). This protects corners
formed at any angle. Multiflex tape bead comes in
100-foot rolls.
Casing and trim beads (examples are shown in fig.
1-56) are used as edge protection and trim around
window and door openings and as moldings at ceiling
angles. They are made from galvanized steel in three
styles to fit 3/8-inch, 1/2-inch, and 5/8-inch wallboard
and come in 10-foot lengths.
Corner and Casing Beads
Expansion Joints
Standard wallboard corner bead is manufactured
from galvanized steel with perforated flanges, as shown
in figure 1-54. It provides a protective reinforcement
of straight corners. The corner bead is made with l-inch
by 1-inch flanges for 3/8- or 1/2-jnch singlelayer wallboard; 1 inch by 1 1/4 inches for 1/2-inch
Expansion joints are vinyl extrusions used as
control joints in drywall partitions and ceilings. A typical
form is shown in figure 1-57.
Figure 1-58 shows a typical metal frame layout and
use of corner and casing beads for corners, partition
intersections, and partition ends. It also shows a typical
Figure 1-57.—Expansion joint.
Figure 1-58.—Metal frame layout with various beads and joints.
Figure 1-59.—Drywall screws and fastening application.
cross section of a metal frame stud wall control joint.
Figure 1-59 lists the different types of fasteners used in
metal frame construction and explains the application of
each type.
supports an attic area beneath a sloping (pitched) roof.
Another type serves as the framework of a flat roof.
When a building has two or more floors, the ceiling of
a lower story is the floor of the story above.
One of the main structural functions of a ceiling
frame is to tie together the outside walls of the building.
When located under a pitched roof, the ceiling frame
this section, you should be able to state the
purpose of ceiling frame members and describe
layout and installation procedures.
also resists the outward pressure placed on the walls by
the roof rafters (fig. 1-60). The tops of interior partitions
are fastened to the ceiling frame. In addition to
supporting the attic area beneath the roof, the ceiling
frame supports the weight of the finish ceiling materials,
Ceiling construction begins after all walls have been
plumbed, aligned, and secured. One type of ceiling
such as gypsum board or lath and plaster.
Figure 1-60.—Ceiling frame tying exterior walls together.
Roof Rafters
Joists are the most important framing members of
the ceiling. Their size, spacing, and direction of travel
Whenever possible, the ceiling joists should run in
the same direction as the roof rafters. Nailing the outside
end of each ceiling joist to the heel of the rafter as well
as to the wall plates (fig. 1-61) strengthens the tie
between the outside walls of the building.
are given on the floor plan. As mentioned earlier, the
spacing between ceiling joists is usually 16 inches OC,
although 24-inch spacing is also used. The size of a
ceiling joist is determined by the weight it carries and
the span it covers from wall to wall. Refer to the
blueprints and specifications for size and OC spacing.
Although it is more convenient to have all the joists
running in the same direction, plans sometimes call for
different sets of joists running at right angles to each
A building maybe designed so that the ceiling joists
do not run parallel to the roof rafters. The rafters are
therefore pushing out on walls not tied together by
ceiling joists. In this case, 2 by 4 pieces are added to run
Interior Support
One end of a ceiling joist rests on an outside wall.
The other end often overlaps an interior bearing partition
or girder. The overlap should be at least 4 inches. Ceiling
joists are sometimes butted over the partition or girder.
In this case, the joists must be cleated with a
3/4-inch-thick plywood board, 24 inches long, or an
18-gauge metal strap, 18 inches long.
Ceiling joists may also butt against the girder,
supported by joist hangers in the same manner as floor
Figure 1-61.—Nailing of ceiling joists.
Figure 1-62.—2 by 4 ties.
Figure 1-63.—Stub joists.
Figure 1-64.—Ribband installation.
with two 16d nails to the top of each ceiling joist, as
shown in figure 1-65. The strongbacks are blocked up
and supported over the outside walls and interior
partitions. Each strongback holds a ceiling joist in line
and also helps support the joist at the center of its span.
in the same direction as the rafters, as shown in
figure 1-62. The 2 by 4s should be nailed to the top of
each ceiling joist with two 16d nails. The 2 by 4 pieces
should be spaced no more than 4 feet apart, and the ends
secured to the heels of the rafters or to blocking over the
outside walls.
Roof Slope
When ceiling joists run in the same direction as the
roof rafters, the outside ends must be cut to the slope of
the roof. Ceiling frames are sometimes constructed with
stub joists (fig. 1-63). Stub joists are necessary when, in
certain sections of the roof, rafters and ceiling joists do
not run in the same direction. For example, a
low-pitched hip roof requires stub joists in the hip
section of the roof.
Ribbands and Strongbacks
Ceiling joists not supporting a floor above require
no header joists or blocking. Without the additional
header joists, however, ceiling joists may twist or bow
at the centers of their span. To help prevent this, nail a
1 by 4 piece called a ribband at the center of the spans
(fig. 1-64). The ribband is laid flat and fastened to the
top of each joist with two 8d nails. The end of each
ribband is secured to the outside walls of the building.
A more effective method of preventing twisting or
bowing of the ceiling joists is to use a strongback. A
strongback is made of 2 by 6 or 2 by 8 material nailed
to the side of a 2 by 4 piece. The 2 by 4 piece is fastened
Figure 1-65.—Strongback.
Figure 1-66.—Ceiling joist spacing.
Figure 1-67.—Constructing a typical ceiling frame.
Figure 1-68.—Backing for nailing joists to ceiling frame.
angle must be cut on the crown (top) side of the joist.
The prepared joists can then be handed up to the
Builders working on top of the walls. The joists are
spread in a flat position along the walls, close to where
the y will be nailed. Figure 1-67 shows one procedure
for constructing the ceiling frame. In this example, the
joists lap over an interior partition. Refer to the figure
as you study the following steps:
Ceiling joists should be placed directly above the
studs when the spacing between the joists is the same as
between the studs. This arrangement makes it easier to
install pipes, flues, or ducts running up the wall and
through the roof. However, for buildings with walls
having double top plates, most building codes do not
require ceiling joists to line up with the studs below.
If the joists are being placed directly above the
studs, they follow the same layout as the studs below
(fig. 1-66, view A). If the joist layout is different from
that of the studs below (for example, if joists are laid out
24 inches OC over a 16 inch OC stud layout), mark the
first joist at 23 1/4 inches and then at every 24 inches
OC (fig. 1-66, view B).
It is a good practice to mark the positions of the roof
rafters at the time the ceiling joists are being laid out. If
the spacing between the ceiling joists is the same as
between the roof railers, there will be a rafter next to
every joist. Often, the joists are laid out 16 inches OC
and the roof rafters 24 inches OC. Therefore, every other
rafter can be placed next to a ceiling joist.
1. Measure and mark for the ceiling joists.
2. Install the ceiling joists on one side of the
3. Install the ceiling joists on the opposite side of
the building.
4. Place backing on walls running parallel to the
5. Install 2 by 4 blocks flat between joists where
needed to fasten the tops of inside walls running
parallel to the joists.
6. Cut and frame the attic scuttle.
7. Place strongbacks at the center of the spans.
Fastening Walls
The tops of walls running in the same direction as
the ceiling joists must be securely fastened to the ceiling
frame. The method most often used is shown in figure
1-68. Blocks, 2 inches by 4 inches, spaced 32 inches OC,
are laid flat over the top of the partition. The ends of
All the joists for the ceiling frame should be cut to
length before they are placed on top of the walls. On
structures with pitched-roofs, the outside ends of the
joists should also be trimmed for the roof slope. This
Figure 1-69.—Backing for interior wall plates.
The scuttle is framed in the same way as a floor
opening. If the opening is no more than 3 feet square, it
is not necessary to double the joists and headers. Scuttles
must be placed away from the lower areas of a sloping
roof. The opening may be covered by a piece of plywood
resting on stops. The scuttle opening can be cut out after
all the regular ceiling joists have been nailed in place.
each block are fastened to the joists with two 16d nails.
Two 16d nails are also driven through each block into
the top of the wall.
Applying Backing
Walls running in the same direction as the ceiling
joists require backing. Figure 1-68 (insert) shows how
backing is nailed to the top plates to provide a nailing
surface for the edges of the finish ceiling material.
Lumber used for backing usually has 2-inch nominal
thickness, although l-inch boards are sometimes used.
Figure 1-68 shows backing placed on top of walls.
The 2 by 4 pieces nailed to the exterior wall projects
from one side of the wall. The interior wall requires a 2
by 6 or 2 by 8 piece extending from both sides of the
wall. Backing is fastened to the top plates with 16d nails
spaced 16 inches OC. Backing is also used where joists
run at right angles to the partition (fig. 1-69).
Although the following references
were current when this TRAMAN was
published, their continued currency
cannot be assured. You therefore need
to ensure that you are studying the
latest revisions.
Carpentry, Leonard Keel, American Technical
Publishers, Alsip, Ill., 1985.
Attic Scuttle
Design of Wood Frame Structures for Permanence,
National Forest Products Association, Washington,
D.C., 1988.
The scuttle is an opening framed in the ceiling to
provide an entrance into the attic area. The size of the
opening is decided by specification requirements and
should be indicated in the blueprints. It must be large
enough for a person to climb through easily.
Exterior and Interior Trim, John E. Ball, Delmar
Publishers, Inc., Albany, N.Y, 1975.
In this chapter, we will introduce you to the
fundamentals of roof design and construction. But,
before discussing roof framing, we will first review
some basic terms and definitions used in roof
construction; we will then discuss the framing square
and learn how it’s used to solve some basic construction
problems. Next, we’ll examine various types of roofs
and rafters, and techniques for laying out, cutting, and
erecting rafters. We conclude the chapter with a
discussion of the types and parts of roof trusses.
The intersecting roof consists of a gable and valley,
or hip and valley. The valley is formed where the two
different sections of the roof meet, generally at a 90°
angle. This type of roof is more complicated than the
this section, you should be able to identify the
types of roofs and define common roof framing
The primary object of a roof in any climate is
protection from the elements. Roof slope and rigidness
are for shedding water and bearing any extra additional
weight. Roofs must also be strong enough to withstand
high winds. In this section, we’ll cover the most
common types of roofs and basic framing terms.
The most commonly used types of pitched roof
construction are the gable, the hip, the intersecting, and
the shed (or lean-to). An example of each is shown in
figure 2-1.
A gable roof has a ridge at the center and slopes in
two directions. It is the form most commonly used by
the Navy. It is simple in design, economical to construct,
and can be used on any type of structure.
The hip roof has four sloping sides. It is the strongest
type of roof because it is braced by four hip rafters.
These hip rafters run at a 45° angle from each corner of
the building to the ridge. A disadvantage of the hip roof
is that it is more difficult to construct than a gable roof.
Figure 2-1.—Most common types of pitched roofs.
other types and requires more time and labor to
The shed roof, or lean-to, is a roof having only one
slope, or pitch. It is used where large buildings are
framed under one roof, where hasty or temporary
construction is needed, and where sheds or additions are
erected. The roof is held up by walls or posts where one
wall or the posts on one side are at a higher level than
those on the opposite side.
Knowing the basic vocabulary is a necessary part of
your work as a Builder. In the following section, we’ll
cover some of the more common roof and rafter terms
you’ll need. Roof framing terms are related to the parts
of a triangle.
Features associated with basic roof framing terms
are shown in figure 2-2. Refer to the figure as you study
the terms discussed in the next paragraphs.
Span is the horizontal distance between the outside
top plates, or the base of two abutting right triangles.
Unit of run is a fixed unit of measure, always 12
inches for the common rafter. Any measurement in a
horizontal direction is expressed as run and is always
measured on a level plane. Unit of span is also fixed,
twice the unit of run, or 24 inches. Unit of rise is the
distance the rafter rises per foot of run (unit of run).
Total run is equal to half the span, or the base of
one of the right triangles. Total rise is the vertical
distance from the top plate to the top of the ridge, or the
altitude of the triangle.
Figure 2-2.—Roof framing terms.
Pitch is the ratio of unit of rise to the unit of span.
It describes the slope of a roof. Pitch is expressed as a
fraction, such as 1/4 or 1/2 pitch. The term “pitch” is
gradually being replaced by the term “cut.” Cut is the
angle that the roof surface makes with a horizontal
plane. This angle is usually expressed as a fraction in
which the numerator equals the unit of rise and the
denominator equals the unit of run (12 inches), such as
6/1 2 or 8/12. This can also be expressed in inches per
foot; for example, a 6- or 8-inch cut per foot. Here, the
unit of run (12 inches) is understood. Pitch can be
converted to cut by using the following formula: unit of
span (24 in.) x pitch = unit of rise. For example,
1/8 pitch is given, so 24 x 1/8 equals 3, or unit of rise
in inches. If the unit of rise in inches is 3, then the cut is
the unit of rise and the unit of run (12 inches), or 3/12.
Line length is the hyptenuse of the triangle whose
base equals the total run and whose altitude equals the
total rise. The distance is measured along the rafter from
the outside edge of the top plate to the centerline of the
ridge. Bridge measure is the hypotenuse of the triangle
with the unit of run for the base and unit of rise for the
Figure 2-3.-Rafter terms.
The members making up the main body of the
framework of all roofs are called rafters. They do for the
roof what the joists do for the floor and what the studs
do for the wall. Rafters are inclined members spaced
from 16 to 48 inches apart. They vary in size, depending
on their length and spacing. The tops of the inclined
rafters are fastened in one of several ways determined
by the type of roof. The bottoms of the rafters rest on
the plate member, providing a connecting link between
the wall and the roof. The rafters are really functional
parts of both the walls and the roof.
Figure 2-4.—Rafter layout.
full distance from plate to ridgeboard. Jack rafters are
subdivided into the hip, valley, and cripple jacks.
In a hip jack, the lower ends rest on the plate and the
upper ends against the hip rafter. In a valley jack the
lower ends rest against the valley rafters and the upper
ends against the ridgeboard. A cripple jack is nailed
between hip and valley rafters.
The structural relationship between the rafters and
the wall is the same in all types of roofs. The rafters are
not framed into the plate, but are simply nailed to it.
Some are cut to fit the plate, whereas others, in hasty
construction, are merely laid on top of the plate and
nailed in place. Rafters usually extend a short distance
beyond the wall to form the eaves (overhang) and
protect the sides of the building. Features associated
with various rafter types and terminology are shown in
figure 2-3.
Rafters are cut in three basic ways (shown in
fig. 2-4, view A). The top cut, also called the plumb cut,
is made at the end of the rafter to be placed against the
ridgeboard or, if the ridgeboard is omitted, against the
opposite rafters. A seat, bottom, or heel cut is made at
the end of the rafter that is to rest on the plate. A side cut
(not shown in fig. 2-4), also called a cheek cut, is a bevel
cut on the side of a rafter to make it fit against another
frame member.
Common rafters extend from the plate to the
ridgeboard at right angles to both. Hip rafters extend
diagonally from the outside corner formed by
perpendicular plates to the ridgeboard. Valley rafters
extend from the plates to the ridgeboard along the lines
where two roofs intersect. Jack rafters never extend the
Rafter length is the shortest distance between the
outer edge of the top plate and the center of the ridge
line. The cave, tail, or overhang is the portion of the
rafter extending beyond the outer edge of the plate. A
measure line (fig. 2-4, view B) is an imaginary reference
line laid out down the middle of the face of a rafter. If a
portion of a roof is represented by a right triangle, the
measure line corresponds to the hypotenuse; the rise to
the altitude; and, the run to the base.
A plumb line (fig. 2-4, view C) is any line that is
vertical (plumb) when the rafter is in its proper position.
A level line (fig. 2-4, view C) is any line that is horizontal
(level) when the rafter is in its proper position.
this section, you should be able to describe and
solve roof framing problems using the framing
The framing square is one of the most frequently
used Builder tools. The problems it can solve are so
many and varied that books have been written on the
square alone. Only a few of the more common uses of
the square can be presented here. For a more detailed
discussion of the various uses of the framing square in
solving construction problems, you are encouraged to
obtain and study one of the many excellent books on the
Figure 2-5.—Framing square: A. Nomenclature; B. Problem
The framing square (fig. 2-5, view A) consists of a
wide, long member called the blade and a narrow, short
member called the tongue. The blade and tongue form
a right angle. The face of the square is the side one sees
when the square is held with the blade in the left hand,
the tongue in the right hand, and the heel pointed away
from the body. The manufacturer’s name is usually
stamped on the face. The blade is 24 inches long and 2
inches wide. The tongue varies from 14 to 18 inches long
and is 1 1/2 inches wide, measured from the outer corner,
where the blade and the tongue meet. This corner is
called the heel of the square.
inches on most squares. Common uses of the twelfths
scale on the back of the framing square will be described
later. The tenths scale is not normally used in roof
The framing square is used most frequently to find
the length of the hypotenuse (longest side) of a right
triangle when the lengths of the other two sides are
known. This is the basic problem involved in
determining the length of a roof rafter, a brace, or any
other member that forms the hypotenuse of an actual or
imaginary right triangle.
The outer and inner edges of the tongue and the
blade, on both face and back, are graduated in inches.
Note how inches are subdivided in the scale on the back
of the square. In the scales on the face, the inch is
subdivided in the regular units of carpenter’s measure
(1/8 or 1/16 inch). On the back of the square, the outer
edge of the blade and tongue is graduated in inches and
twelfths of inches. The inner edge of the tongue is
graduated in inches and tenths of inches. The inner edge
of the blade is graduated in inches and thirty-seconds of
Figure 2-5, view B, shows you how the framing
square is used to determine the length of the hypotenuse
of a right triangle with the other sides each 12 inches
long. Place a true straightedge on a board and set the
square on the board so as to bring the 12-inch mark on
Figure 2-6.—"Stepping off" with a framing square.
Figure 2-7.–"Stepping off" with a square when the unit of run
and unit of rise are different.
the tongue and the blade even with the edge of the board.
Draw the pencil marks as shown. The distance between
these marks, measured along the edge of the board, is
the length of the hypotenuse of a right triangle with the
other sides each 12 inches long. You will find that the
distance, called the bridge measure, measures just under
17 inches—16.97 inches, as shown in the figure. For
most practical Builder purposes, though, round 16.97
inches to 17 inches.
a general custom of the trade, unit of run is always taken
as 12 inches and measured on the tongue of the framing
Now, if the total run is 48 inches, the total rise is 48
inches, and the unit of run is 12 inches, what is the unit
of rise? Well, since the sides of similar triangles are
proportional, the unit of rise must be the value of x in
the proportional equation 48:48::12:x. In this case, the
unit of rise is obviously 12 inches.
Solving for Unit and Total Run and Rise
To get the length of the brace, set the framing square
to the unit of run (12 inches) on the tongue and to the
unit of rise (also 12 inches) on the blade, as shown in
figure 2-6. Then, “step off” this cut as many times as the
unit of run goes into the total run. In this case, 48/12, or
4 times, as shown in the figure.
In figure 2-5, the problem could be solved by a
single set (called a cut) of the framing square. This was
due to the dimensions of the triangle in question lying
within the dimensions of the square. Suppose, though,
you are trying to find the length of the hypotenuse of a
right triangle with the two known sides each being 48
inches long. Assume the member whose length you are
trying to determine is the brace shown in figure 2-6. The
total run of this brace is 48 inches, and the total rise is
also 48 inches.
In this problem, the total run and total rise were the
same, from which it followed that the unit of run and
unit of rise were also the same. Suppose now that you
want to know the length of a brace with a total run of 60
inches and a total rise of 72 inches, as in figure 2-7. Since
the unit of run is 12 inches, the unit of rise must be the
value of x in the proportional equation 60:72::12.x. That
is, the proportion 60:72 is the same as the proportion
12:x. Working this out, you find the unit of rise is
To figure the length of the brace, you first reduce
the triangle in question to a similar triangle within the
dimensions of the framing square. The length of the
vertical side of this triangle is called unit of rise, and the
length of the horizontal side is called the unit of run. By
72 inches long is slightly more than 93.72 inches, but
93 3/4 inches is close enough for practical purposes.
Once you know the total length of the member, just
measure it off and make the end cuts. To make these cuts
at the proper angles, set the square to the unit of run on
the tongue and the unit of rise on the blade and draw a
line for the cut along the blade (lower end cut) or the
tongue (upper end cut).
A framing square contains four scales: tenths,
twelfths, hundredths, and octagon. All are found on the
face or along the edges of the square. As we mentioned
earlier, the tenths scale is not used in roof framing.
Twelfths Scale
The graduations in inches, located on the back of
the square along the outer edges of the blade and tongue,
are called the twelfths scale. The chief purpose of the
twelfths scale is to provide various shortcuts in problem
solving graduated in inches and twelfths of inches.
Dimensions in feet and inches can be reduced to 1/12th
by simply allowing each graduation on the twelfths scale
to represent 1 inch; for example, 2 6/12 inches on the
twelfths scale may be taken to represent 2 feet 6 inches.
A few examples will show you how the twelfths scale
is used.
Figure 2-8.-Unit length.
14.4 inches. For practical purposes, you can round this
to 14 3/8.
To lay out the full length of the brace, set the square
to the unit of rise (14 3/8 inches) and the unit of run
(12 inches), as shown in figure 2-7. Then, step off this
cut as many times as the unit of run goes into the total
run (60/12, or 5 times).
Suppose you want to know the total length of a rafter
with a total run of 10 feet and a total rise of 6 feet
5 inches. Set the square on a board with the twelfths
scale on the blade at 10 inches and the twelfths scale on
the tongue at 6 5/12 inches and make the usual marks.
If you measure the distance between the marks, you will
find it is 11 11/12 inches. The total length of the rafter
is 11 feet 11 inches.
Determining Line Length
If you do not go through the stepping-off procedure,
you can figure the total length of the member in question
by first determining the bridge measure. The bridge
measure is the length of the hypotenuse of a right
triangle with the other sides equal to the unit of run and
unit of rise. Take the situation shown above in figure 2-7.
The unit of run here is 12 inches and the unit of rise is
14 3/8 inches. Set the square to this cut, as shown in
figure 2-8, and mark the edges of the board as shown. If
you measure the distance between the marks, you will
find it is 18 3/4 inches. Bridge measure can also be found
by using the Pythagorean theorem: (a2 + bz = C2). Here,
the unit of rise is the altitude (a), the unit or run is the
base (b), and the hypotenuse (c) is the bridge measure.
Suppose now that you know the unit of run, unit of
rise, and total run of a rafter, and you want to find the
total rise and the total length. Use the unit of run
(12 inches) and unit of rise (8 inches), and total run of
8 feet 9 inches. Set the square to the unit of rise on the
tongue and unit of run on the blade (fig. 2-9, top view).
Then, slide the square to the right until the 8 9/12-inch
mark on the blade (representing the total run of 8 feet
9 inches) comes even with the edge of the board, as
shown in the second view. The figure of 5 10/12 inches,
now indicated on the tongue, is one-twelfth of the total
rise. The total rise is, therefore, 5 feet 10 inches. The
distance between pencil marks (10 7/12 inches) drawn
along the tongue and the blade is one-twelfth of the total
length. The total length is, therefore, 10 feet 7 inches.
To get the total length of the member, you simply
multiply the bridge measure in inches by the total run in
feet. Since that is 5, the total length of the member is
18 3/4 x 5, or 93 3/4 inches. Actually, the length of the
hypotenuse of a right triangle with the other sides 60 and
Figure 2-9.-Finding total rise and length when unit of run, unit
of rise, and total run are known.
Figure 2-10.—Using the octagon square.
The twelfths scale may also be used to determine
dimensions by inspection for proportional reductions or
enlargements. Suppose you have a panel 10 feet 9 inches
long by 7 feet wide. You want to cut a panel 7 feet long
with the same proportions. Set the square, as shown in
figure 2-9, but with the blade at 10 9/12 inches and the
tongue at 7 inches. Then slide the blade to 7 inches and
read the figure indicted on the tongue, which will be
4 7/12 inches if done correctly. The smaller panel should
then be 4 feet 7 inches wide.
Octagon Scale
The octagon scale (sometimes called the eightsquare scale) is located in the middle of the face of the
tongue. The octagon scale is used to lay out an octagon
(eight-sided figure) in a square of given even-inch
Let’s say you want to cut an 8-inch octagonal piece
for a stair newel. First, square the stock to 8 by 8 inches
and smooth the end section. Then, draw crossed center
lines on the end section, as shown in figure 2-10. Next,
set a pair of dividers to the distance from the first to the
eighth dot on the octagon scale, and layoff this distance
on either side of the centerline on the four slanting sides
of the octagon. This distance equals one-half the length
of a side of the octagon.
Hundredths Scale
The hundredths scale is on the back of the tongue,
in the comer of the square, near the brace table. This
scale is called the hundredths scale because 1 inch is
divided into 100 parts. The longer lines indicate
25 hundredths, whereas the next shorter lines indicate
5 hundredths, and so forth. By using dividers, you can
easily obtain a fraction of an inch.
When you use the octagon scale, set one leg of the
dividers on the first dot and the other leg on the dot
whose number corresponds to the width in inches of the
square from which you are cutting the piece.
The inch is graduated in sixteenths and located
below the hundredths scale. Therefore, the conversion
from hundredths to sixteenths can be made at a glance
without the use of dividers. This can be a great help
when determining rafter lengths, using the figures of the
rafter tables where hundredths are given.
There are three tables on the framing square: the unit
length rafter table, located on the face of the blade; the
Figure 2-11.-Brace table.
brace table, located on the back of the tongue; and the
Essex board measure table, located on the back of the
blade. Before you can use the unit length rafter table,
you must be familiar with the different types of rafters
and with the methods of framing them. The use of the
unit length rafter table is described later in this chapter.
The other two tables are discussed below.
two sides 27 units long, 38.18 units; two sides 30 units
long, 42.43 units; and so on.
By applying simple arithmetic, you can use the
brace table to determine the hypotenuse of a right
triangle with equal sides of practically any even-unit
length. Suppose you want to know the length of the
hypotenuse of a right triangle with two sides 8 inches
long. The brace table shows that a right triangle with two
sides 24 inches long has a hypotenuse of 33.94 inches.
Since 8 amounts to 24/3, a right triangle with two shorter
sides each 8 inches long must have a hypotenuse of
The brace table sets forth a series of equal runs and
rises for every three-units interval from 24/24 to 60/60,
together with the brace length, or length of the
hypotenuse, for each given run and rise. The table can
be used to determine, by inspection, the length of the
hypotenuse of a right triangle with the equal shorter
sides of any length given in the table. For example, in
the segment of the brace table shown in figure 2-11, you
can see that the length of the hypotenuse of a right
triangle with two sides 24 units long is 33.94 units; with
33.94 ÷3, or approximately 11.31 inches.
Suppose you want to find the length of the
hypotenuse of a right triangle with two sides 40 inches
each. The sides of similar triangles are proportional, and
any right triangle with two equal sides is similar to any
other right triangle with two equal sides. The brace table
shows that a right triangle with the two shorter sides
Figure 2-12.-Segment of Essex board measure table.
dimensions. The inch graduations (fig. 2-12, view A)
being 30 inches long has a hypotenuse of 42.43 inches.
The length of the hypotenuse of a right triangle with the
two shorter sides being 40 inches long must be the value
of x in the proportional equation 30.42.43::40:x, or
about 56.57 inches.
above the table (1, 2, 3, 4, and so on) represent the width
in inches of the piece to be measured. The figures under
the 12-inch graduation (8, 9, 10, 11, 13, 14, and 15,
arranged in columns) represent lengths in feet. The
figure 12 itself represents a 12-foot length. The column
headed by the figure 12 is the starting point for all
Notice that the last item in the brace table (the one
farthest to the right in fig. 2-11) gives you the
hypotenuse of a right triangle with the other proportions
18:24:30. These proportions are those of the most
common type of unequal-sided right triangle, with sides
in the proportions of 3:4:5.
To use the table, scan down the figure 12 column to
the figure that represents the length of the piece of
lumber in feet. Then go horizontally to the figure
Essex Board
directly below the inch mark that corresponds to the
width of the stock in inches. The figure you find will be
The primary use of the Essex board measure table
is for estimating the board feet in lumber of known
the number of board feet and twelfths of board feet in a
1-inch-thick board.
Let’s take an example. Suppose you want to figure
the board measure of a piece of lumber 10 feet long by
10 inches wide by 1 inch thick. Scan down the column
(fig. 2-12, view B) headed by the 12-inch graduation to
10, and then go horizontally to the left to the figure
directly below the 10-inch graduation. You will find the
figure to be 84, or 8 4/12 board feet. For easier
calculating purposes, you can convert 8 4/12 to a
decimal (8.33).
To calculate the cost of this piece of lumber,
multiply the cost per board foot by the total number of
board feet. For example, a 1 by 10 costs $1.15 per board
foot. Multiply the cost per board foot ($1. 15) by the
number of board feet (8.33). This calculation is as
Figure 2-13.—Framework of a gable roof.
What do you do if the piece is more than 1 inch
thick? All you have to do is multiply the result obtained
for a 1-inch-thick piece by the actual thickness of the
piece in inches. For example, if the board described in
the preceding paragraph were 5 inches thick instead of
1 inch thick, you would follow the procedure described
and then multiply the result by 5.
The board measure scale can be read only for
lumber from 8 to 15 feet in length. If your piece is longer
than 15 feet, you can proceed in one of two ways. If the
length of the piece is evenly divisible by one of the
lengths in the table, you can read for that length and
multiply the result by the number required to equal the
piece you are figuring. Suppose you want to find the
number of board feet in a piece 33 feet long by 7 inches
wide by 1 inch thick. Since 33 is evenly divisible by 11,
scan down the 12-inch column to 11 and then go left to
the 7-inch column. The figure given there (which is
65/12, or 6.42 bd. ft.) is one-third of the total board feet.
The total number of board feet is 6 5/12 (or 6.42) x 3,
or 19 3/12 (or 19.26) board feet.
Figure 2-14.—Typical common rafter with an overhang.
If the length of the piece is not evenly divisible by
one of the tabulated lengths, you can divide it into two
tabulated lengths, read the table for these two, and add
the results together. For example, suppose you want to
find the board measure of a piece 25 feet long by
10 inches wide by 1 inch thick. This length can be
divided into 10 feet and 15 feet. The table shows that the
10-foot length contains 8 4/12 (8.33) board feet and the
15-foot length contains 12 6/12 (12.5) board feet. The
total length then contains 8 4/12 (8.33) plus 12 6/12
(12.5), or 20 10/12 (20.83) board feet.
this section, you should be able to describe
procedures for the layout and installation of
members of gable, hip, intersecting, and shed
roof designs.
As we noted earlier, the four most common roof
designs you will encounter as a Builder are gable, hip,
intersecting, and shed. In this section, we will examine
Common Rafters
All common rafters for a gable roof are the same
length. They can be precut before the roof is assembled.
Today, most common rafters include an overhang. The
overhang (an example is shown in fig. 2-14) is the part
of the rafter that extends past the building line. The run
of the overhang, called the projection, is the horizontal
distance from the building line to the tail cut on the
rafter. In figure 2-14, note the plumb cuts at the ridge,
heel, and tail of the rafter. A level seat cut is placed where
the rafter rests on the top plate. The notch formed by the
seat and heel cut line (fig. 2-15) is often called the
The width of the seat cut is determined by the slope
of the roof: the lower the slope, the wider the cut. At
least 2 inches of stock should remain above the seat cut.
The procedure for marking these cuts is explained later
in this chapter. Layout is usually done after the length
of the rafter is calculated.
Figure 2-15.—A “bird’s-mouth” is formed by the heel plumb
line and seat line.
various calculations, layouts, cutting procedures, and
assembly requirements required for efficient construction.
RAFTERS.— The length of a common rafter is based
on the unit of rise and total run of the roof. The unit of
rise and total run are obtained from the blueprints. Three
different procedures can be used to calculate common
rafter length: use a framing square printed with a rafter
table; use a book of rafter tables; or, use the step-off
method where rafter layout is combined with calculating
Next to the shed roof, which has only one slope, the
gable roof is the simplest type of sloping roof to build
because it slopes in only two directions. The basic
structural members of the gable roof are the ridgeboard,
the common rafters, and the gable-end studs. The
framework is shown in figure 2-13.
Framing squares are available with a rafter table
printed on the face side (fig. 2-16). The rafter table
makes it possible to find the lengths of all types of
rafters for pitched roofs, with unit of rises ranging from
2 inches to 18 inches. Let’s look at two examples:
The ridgeboard is placed at the peak of the roof. It
provides a nailing surface for the top ends of the
common rafters. The common rafters extend from the
top wall plates to the ridge. The gable-end studs are
upright framing members that provide a nailing surface
for siding and sheathing at the gable ends of the roof.
Example 1. The roof has a 7-inch unit of rise and
a 16-foot span.
Figure 2-16.—Rafter table on face of a steel square.
Step 2. To change .12 of an inch to a fraction of
an inch, multiply by 16:
The number 1 to the left of the decimal point
represents 1/16 inch. The number .92 to the right of the
decimal represents ninety-two hundredths of 1/16 inch.
For practical purposes, 1.92 is calculated as being equal
to 2 x 1/16 inch, or 1/8 inch. As a general rule in this
kind of calculation, if the number to the right of the
decimal is 5 or more, add 1/16 inch to the figure on the
left side of the decimal. The result of steps 1 and 2 is a
total common rafter length of 111 1/8 inches, or 9 feet
3 1/8 inches.
Example 2. A roof has a 6-inch unit of rise and a
25-foot span. The total run of the roof
is 12 feet 6 inches. You can find the
rafter length in four steps.
Figure 2-17.—Rafter length.
Step 1.
Look at the first line of the rafter table on a framing
FOOT RUN (also known as the bridge measure). Since
the roof in this example has a 7-inch unit of rise, locate
the number 7 at the top of the square. Directly beneath
the number 7 is the number 13.89. This means that a
common rafter with a 7-inch unit of rise will be
13.89 inches long for every unit of run. To find the
length of the rafter, multiply 13.89 inches by the
number of feet in the total run. (The total run is always
one-half the span.) The total run for a roof with a 16-foot
span is 8 feet; therefore, multiply 13.89 inches by 8 to
find the rafter length. Figure 2-17 is a schematic of this
Change 6 inches to a fraction of a foot by
placing the number 6 over the number 12:
(1/2 foot = 6 inches).
Step 2.
Change the fraction to a decimal by
dividing the bottom number (denominator) into the top number (numerator):
(.5 foot = 6 inches).
Step 3.
Multiply the total run (12.5) by the length
of the common rafter per foot of run
(13.42 inches) (fig. 2-16):
If a framing square is not available, the bridge
measure can be found by using the Pythgorean theorum
root of 193 is 13.89.
Step 4. To change .75 inch to a fraction of an inch,
multiply by 16 (for an answer expressed
in sixteenths of an inch).
Two steps remain to complete the procedure.
Step 1. Multiply the number of feet in the total run
(8) by the length of the common rafter per
foot of run (13.89 inches):
.75 x 16 = 12
The result of these steps is a total common rafter
length of 167 3/4 inches, or 13 feet 11 3/4 inches.
usually 1 1/2 inches thick, is placed between the rafters,
one-half of the ridgeboard (3/4 inch) must be deducted
from each rafter. This calculation is known as shortening
the rafter. It is done at the time the rafters are laid out.
The actual length (as opposed to the theoretical length)
of a ratler is the distance from the heel plumb line to the
shortened ridge plumb line (fig. 2-18).
Figure 2-18.—The actual (versus theoretical) length of a common
Figure 2-19.-Steel square used to lay out plumb and seat cuts.
SHORTENING.— Rafter length found by any of
the methods discussed here is the measurement from the
heel plumb line to the center of the ridge. This is known
as the theoretical length of the rafter. Since a ridgeboard,
LAYING OUT.— Before the rafters can be cut, the
angles of the cuts must be marked. Layout consists of
marking the plumb cuts at the ridge, heel, and tail of the
rafter, and the seat cut where the rafter will rest on the
wall. The angles are laid out with a framing square, as
shown in figure 2-19. A pair of square gauges is useful
in the procedure. One square gauge is secured to the
tongue of the square next to the number that is the same
as the unit of rise. The other gauge is secured to the blade
of the square next to the number that is the same as the
unit of run (always 12 inches). When the square is placed
on the rafter stock, the plumb cut can be marked along
the tongue (unit of rise) side of the square. The seat cut
can be marked along the blade (unit of run) side of the
Rafter layout also includes marking off the required
overhang, or tail line length, and making the shortening
calculation explained earlier. Overhang, or tail line
length, is rarely given and must be calculated before
laying out rafters. Projection, the horizontal distance
from the building line to the rafter tail, must be located
from drawings or specifications. To determine tail line
length, use the following formula: bridge measure (in
inches) times projection (in feet) equals tail line length
(in inches). Determine the bridge measure by using the
rafter table on the framing square or calculate it by using
the Pythagorean theorem. Using figure 2-20 as a guide,
you can see there are four basic steps remaining.
Figure 2-20.—Laying out a common rafter for a gable roof.
Figure 2-21.-Step-off method for calculating common rafter length.
Step 1. Lay out the rafter line length. Hold the
framing square with the tongue in your
right hand, the blade in the left, and the
heel away from your body. Place the
square as near the right end of the rafter
as possible with the unit of rise on the
tongue and the unit of run on the blade
along the edge of the rafter stock. Strike a
plumb mark along the tongue on the wide
part of the material. This mark represents
the center line of the roof. From either end
of this mark, measure the line length of the
rafter and mark the edge of the rafter
stock. Hold the framing square in the same
manner with the 6 on the tongue on the
mark just made and the 12 on the blade
along the edge. Strike a line along the
tongue, his mark represents the plumb
cut of the heel.
Step 2.
Lay out the bird’s-mouth. Measure 1 1/2
inches along the heel plumb line up from
the bottom of the rafter. Set the blade of
the square along the plumb line with the
heel at the mark just made and strike a line
along the tongue. This line represents the
seat of the bird’s-mouth.
Step 3.
Lay out the tail line length. Measure the
tail line length from the bird’ s-mouth heel
plumb line. Strike a plumb line at this
point in the same manner as the heel
plumb line of the common rafter.
Step 4.
Lay out the plumb cut at the ridgeboard.
Measure and mark the point along the line
length half the thickness of the ridgeboard. (This is the ridgeboard shortening
allowance.) Strike a plumb line at this
point. This line represents the plumb cut
of the ridgeboard.
Step-Off Calculations and Layout
The step-off method for rafter layout is old but still
practiced. It combines procedures for laying out the
rafters with a procedure of stepping off the length of the
rafter (see fig. 2-21). In this example, the roof has an
8-inch unit of rise, a total run of 5 feet 9 inches, and a
10-inch projection.
First, set gauges at 8 inches on the tongue and
12 inches on the blade. With the tongue in the right
hand, the blade in the left hand, and the heel away
from the body, place the square on the right end of
the rafter stock. Mark the ridge plumb line along the
tongue. Put a pencil line at the 12-inch point of the blade.
Second, with the gauges pressed lightly against the
rafter, slide the square to the left. Line the tongue up with
the last 12-inch mark and make a second 12-inch mark
along the bottom of the blade.
Third, to add the 9-inch remainder of the total run,
place the tongue on the last 12-inch mark. Draw another
mark at 9 inches on the blade. This will be the total
length of the rafter.
Last, lay out and cut the plumb cut line and the seat
cut line.
Roof Assembly
The major part of gable-roof construction is setting
the common rafters in place. The most efficient method
is to precut all common rafters, then fasten them to the
ridgeboard and the wall plates in one continuous
The rafter locations should be marked on the top
wall plates when the positions of the ceiling joists are
laid out. Proper roof layout ensures the rafters and joists
tie into each other wherever possible.
The ridgeboard like the common rafters, should be
precut. The rafter locations are then copied on the
ridgeboard from the markings on the wall plates
(fig. 2-22). The ridgeboard should be the length of the
building plus the overhang at the gable ends.
Figure 2-22.—Ridgeboard layout.
Figure 2-23.—Calculation for a collar tie.
The material used for the ridgeboard is usually
wider than the rafter stock. For example, a ridgeboard
of 2- by 8-inch stock would be used with rafters of 2by 6-inch stock. Some buildings are long enough to
require more than one piece of ridge material. The
breaks between these ridge pieces should occur at the
center of a rafter.
One pair of rafters should be cut and checked for
accuracy before the other rafters are cut. To check the
first pair for accuracy, set them in position with a 1
1/2-inch piece of wood fitted between them. If the
rafters are the correct length, they should fit the building.
If, however, the building walls are out of line,
adjustments will have to be made on the rafters.
After the first pair of rafters is checked for accuracy
(and adjusted if necessary), one of the pair can be used
as a pattern for marking all the other rafters. Cutting is
usually done with a circular or radial-arm saw.
COLLAR TIE.— Gable or double-pitch roof
rafters are often reinforced by horizontal members
Figure 2-24.—Laying out end cut on a collar tie.
Figure 2-25.-Setting up and bracing a ridgeboard when only a few workers are available.
Common rafter overhang can be laid out and cut
before the rafters are set in place. However, many
Builders prefer to cut the overhang after the rafters are
fastened to the ridgeboard and wall plates. A line is
snapped from one end of the building to the other, and
the tail plumb line is marked with a sliding T-bevel, also
called a bevel square. These procedures are shown in
figure 2-26. The rafters are then cut with a circular saw.
called collar ties (fig. 2-23). In a finished attic, the ties
may also function as ceiling joists.
To find the line length of a collar tie, divide the
amount of drop of the tie in inches by the unit of rise of
the common rafter. This will equal one-half the length
of the tie in feet. Double the result for the actual length.
The formula is as follows: Drop in inches times 2,
divided by unit or rise, equals the length in feet.
The length of the collar tie depends on whether the
drop is measured to the top or bottom edge of the collar
tie (fig. 2-23). The tie must fit the slope of the roof. To
obtain this angle, use the framing square. Hold the unit
of run and the unit of rise of the common rafter. Mark
and cut on the unit of run side (fig. 2-24).
METHODS OF RIDGE BOARD ASSEMBLY.— Several different methods exist for setting up
the ridgeboard and attaching the rafters to it. When only
a few Builders are present, the most convenient
procedure is to set the ridgeboard to its required height
(total rise) and hold it in place with temporary vertical
props (fig. 2-25). The rafters can then be nailed to the
ridgeboard and the top wall plates.
Plywood panels should be laid on top of the ceiling
joists where the framing will take place. The panels
provide safe and comfortable footing. They also provide
a place to put tools and materials.
Figure 2-26.-Snapping a line and marking plumb cuts for a
gable-end overhang.
Figure 2-27.-Gable-end overhang with the end wall framed under the overhang.
Figure 2-28.-Gable-end overhang with the end wall framed directly beneath the rafters.
This method guarantees that the line of the overhang will
be perfectly straight, even if the building is not.
Over each gable end of the building, another
overhang can be framed. The main framing members of
the gable-end overhang are the fascia, also referred to
as “fly” (or “barge”) rafters. They are tied to the
ridgeboard at the upper end and to the fascia board at
the lower end. Fascia boards are often nailed to the tail
ends of the common rafters to serve as a finish piece at
the edge of the roof. By extending past the gable ends
of the house, common rafters also help to support the
basic rafters.
Figures 2-27 and 2-28 show different methods used
to frame the gable-end overhang. In figure 2-27, a fascia
rafter is nailed to the ridgeboard and to the fascia board.
Blocking (not shown in the figures) rests on the end wall
and is nailed between the fascia rafter and the rafter next
to it. This section of the roof is further strengthened
when the roof sheathing is nailed to it. In figure 2-28,
two common rafters arc placed directly over the gable
Figure 2-29.—Calculating common difference of gable-end studs.
The lengths of the other gable studs depend on the
The common difference in the length of the gable
studs may be figured by the following method:
ends of the building. The fascia rafters (fly rafters) are
placed between the ridgeboard and the fascia boards.
The gable studs should be cut to fit against the rafter
End Framing
Gable-end studs rest on the top plate and extend to
the rafter line in the ends of a gable roof. They may be
placed with the edge of the stud even with the outside
wall and the top notched to fit the rafter (as shown in fig.
2-28), or they maybe installed flatwise with a cut on the
top of the stud to fit the slope of the rafter.
The position of the gable-end stud is located by
squaring a line across the plate directly below the center
of the gable. If a window or vent is to be installed in the
gable, measure one-half of the opening size on each side
of the center line and make a mark for the first stud.
Starting at this mark layout the stud spacing (that is, 16
or 24 inches on center [OC]) to the outside of the
building. Plumb the gable-end stud on the first mark and
mark it where it contacts the bottom of the rafter, as
shown in figure 2-29, view A. Measure and mark
3 inches above this mark and notch the stud to the depth
equal to the thickness of the rafter, as shown in view B.
and, 2 x 6 inches (unit of rise) or 12 inches (common
The common difference in the length of the gable
studs may also be laid out directly with the framing
square (fig. 2-29, view C). Place the framing square on
the stud to the cut of the roof (6 and 12 inches for this
example). Draw a line along the blade at A. Slide the
square along this line in the direction of the arrow at B
until the desired spacing between the studs (16 inches
for this example) is at the intersection of the line drawn
at A and the edge of the stud. Read the dimension on the
tongue aligned with the same edge of the stud (indicated
by C). This is the common difference (8 inches for this
example) between the gable studs.
Toenail the studs to the plate with two 8d nails in
each side. As the studs are nailed in place, care must be
taken not to force a crown into the top of the rafter.
Figure 2-30.—Equal-pitch hip roof framing diagram.
The ridge-end common rafters AC, AD, AE, BH, BJ,
and BL join the ridge at the same points.
Most hip roofs are equal pitch. This means the angle
of slope on the roof end or ends is the same as the angle
of slope on the sides. Unequal-pitch hip roofs do exist,
but they are quite rare. They also require special layout
methods. The unit length rafter table on the framing
square applies only to equal-pitch hip roofs. The next
paragraphs discuss an equal-pitch hip roof.
A line indicating a rafter in the roof framing diagram
is equal in length to the total run of the rafter it
represents. You can see from the diagram that the total
run of a hip rafter (represented by lines AF-AG-BI-BK)
is the hypotenuse of a right triangle with the altitude and
base equal to the total run of a common rafter. You know
the total run of a common rafter: It is one-half the span,
or one-half the width of the building. Knowing this, you
can find the total run of a hip rafter by applying the
Pythagorean theorem.
The length of a hip rafter, like the length of a
common rafter, is calculated on the basis of bridge
measure multiplied by the total run (half span). Any of
the methods previously described for a common rafter
may be used, although some of the dimensions for a hip
rafter are different.
Let’s suppose, for example, that the span of the
building is 30 feet. Then, one-half the span, which is the
same as the total run of a common rafter, is 15 feet.
Applying the Pythagorean theorem, the total run of a hip
rafter is:
Figure 2-30 shows part of a roof framing diagram
for an equal-pitch hip roof. A roof framing diagram
may be included among the working drawings; if not,
you should lay one out for yourself. Determine what
scale will be used, and lay out all framing members
to scale. Lay the building lines out first. You can find
the span and the length of the building on the working
drawings. Then, draw a horizontal line along the
center of the span.
What is the total rise? Since a hip rafter joins the
ridge at the same height as a common rafter, the total
rise for a hip rafter is the same as the total rise for a
common rafter. You know how to figure the total rise of
a common rafter. Assume that this roof has a unit of run
of 12 and a unit of rise of 8. Since the total run of a
common rafter in the roof is 15 feet, the total rise of
common rafter is the value of x in the proportional
equation 12:8::15:x, or 10 feet.
In an equal-pitch hip roof framing diagram, the lines
indicating the hip rafters (AF, AG, BI, and BK in figure
2-30) form 45° angles with the building lines. Draw
these lines at 45°, as shown. The points where they meet
the center line are the theoretical ends of the ridge piece.
case, is 15 feet. The length of the hip rafter is therefore
Knowing the total run of the hip rafter (21.21 feet)
and the total rise (10 feet), you can figure the line length
by applying the Pythagorean theorem. The line length
18.76 x 15, or 281.40 inches—23.45 feet once
You step off the length of an equal-pitch hip roof
just as you do the length of a common rafter, except that
you set the square to a unit of run of 16.97 inches instead
of to a unit of run of 12 inches. Since 16.97 inches is the
same as 16 and 15.52 sixteenths of an inch, setting the
square to a unit of run of 17 inches is close enough for
most practical purposes. Bear in mind that for any plumb
cut line on an equal-pitch hip roof rafter, you set the
square to the unit of rise of a common rafter and to a unit
of run of 17.
To find the length of a hip rafter on the basis of
bridge measure, you must first determine the bridge
measure. As with a common rafter, the bridge measure
of a hip rafter is the length of the hypotenuse of a triangle
with its altitude and base equal to the unit of run and unit
of rise of the rafter. The unit of rise of a hip rafter is
always the same as that of a common rafter, but the unit
of run of a hip rafter is a fixed unit of measure, always
You step off the same number of times as there are
feet in the total run of a common rafter in the same roof;
only the size of each step is different. For every 12-inch
step in a common rafter, a hip rafter has a 17-inch step.
For the roof on which you are working, the total run of
common rafter is exactly 15 feet; this means that you
would step off the hip-rafter cut (17 inches and 8 inches)
exactly 15 times.
The unit of run of a hip rafter in an equal-pitch roof
is the hypotenuse of a right triangle with its altitude and
base equal to the unit of run of a common rafter, 12.
Therefore, the unit of run of a hip rafter is:
Suppose, however, that there was an odd unit in the
common rafter total run. Assume, for example, that the
total run of a common rafter is 15 feet 10 1/2 inches.
How would you make the odd fraction of a step on the
hip rafter?
If the unit of run of a hip rafter is 16.97 and the unit
of rise (in this particular case) is 8, the bridge measure
of the hip rafter must be:
You remember that the unit of run of a hip rafter is
the hypotenuse of a right triangle with the other side
each equal to the unit of run of a common rafter. In this
case, the run of the odd unit on the hip rafter must be the
hypotenuse of a right triangle with the altitude and base
equal to the odd unit of run of the common rafter (in this
case, 10 1/2 inches). You can figure this using the
Pythagorean theorem
This means that for every unit of run (16.97) the
rafter has a line length of 18.76 inches. Since the total
run of the rafter is 21.21 feet, the length of the rafter
must be the value of x in the proportional equation
16.97:18.76::21.21:x, or 23.45 feet.
Like the unit length of a common rafter, the bridge
measure of a hip rafter can be obtained from the unit
length rafter table on the framing square. If you turn
back to figure 2-16, you will see that the second line in
the table is headed LENGTH HIP OR VALLEY PER
FT RUN. This means “per foot run of a common rafter
in the same roof.” Actually, the unit length given in the
tables is the unit length for every 16.97 units of run of
the hip rafter itself. If you go across to the unit length
given under 8, you will find the same figure, 18.76 units,
that you calculated above.
or you can set the square on a true edge to 10 1/2 inches
on the blade and measure the distance between the
marks. It comes to 14.84 inches. Rounded off to the
nearest 1/16 inch, this equals 14 13/16 inches.
To layoff the odd unit, set the tongue of the framing
square to the plumb line for the last full step made and
measure off 14 13/16 inches along the blade. Place the
tongue of the square at the mark, set the square to the
hip rafter plumb cut of 8 inches on the tongue and
17 inches on the blade, and draw the line length cut.
An easy way to calculate the length of an
equal-pitch hip roof is to multiply the bridge measure
by the number of feet in the total run of a common rafter,
which is the same as the number of feet in one-half of
the building span. One-half of the building span, in this
Figure 2-31.-Shortening a hip rafter.
Rafter Shortening Allowance
the ridge piece (fig. 2-31, view C). The 45° thickness of
stock is the length of a line laid at 45° across the
thickness dimension of the stock. If the hip rafter is
framed against the common rafter, the shortening
allowance is one-half of the 45° thickness of a common
As in the case with a common rafter, the line length
of a hip rafter does not take into account the thickness
of the ridge piece. The size of the ridge-end shortening
allowance for a hip rafter depends upon the way the
ridge end of the hip rafter is joined to the other structural
members. As shown in figure 2-31, the ridge end of the
hip rafter can be framed against the ridgeboard (view A)
or against the ridge-end common rafters (view B). To
calculate the actual length, deduct one-half the 45°
thickness of the ridge piece that fits between the rafters
from the theoretical length.
To lay off the shortening allowance, first set the
tongue of the framing square to the line length ridge cut
line. Then, measure off the shortening allowance along
the blade, set the square at the mark to the cut of the
rafter (8 inches and 17 inches), draw the actual ridge
plumb cut line. (To find the 45° thickness of a piece of
lumber, draw a 450 line across the edge, and measure
the length of the line and divide by 2.)
When no common rafters are placed at the ends of
the ridgeboard the hip rafters are placed directly against
the ridgeboard. They must be shortened one-half the
length of the 45° line (that is, one-half the thickness of
the ridgeboard When common rafters are placed at the
ends of the ridgeboard (view B), the hip rafter will fit
between the common rafters. The hip rafter must be
shortened one-half the length of the 45° line (that is,
one-half the thickness of the common rafter).
Rafter Projection
A hip or valley rafter overhang, like a common
rafter overhang, is figured as a separate rafter. The
projection, however, is not the same as the projection of
a common rafter overhang in the same roof. The
projection of the hip or valley rafter overhang is the
hypotenuse of a right triangle whose shorter sides are
each equal to the run of a common rafter overhang
(fig. 2-32). If the run of the common rafter overhang is
If the hip rafter is framed against the ridge piece, the
shortening allowance is one-half of the 45° thickness of
Figure 2-32.—Run of hip rafter projection.
18 inches for a roof with an 8-inch unit of rise, the length
of the hip or valley rafter tail is figured as follows:
1. Find the bridge measure of the hip or valley
rafter on the framing square (refer to figure
2-16). For this roof, it is 18.76 inches.
Figure 2-33.—Laying out hip rafter side cut.
2. Multiply the bridge measure (in inches) of the
hip or valley rafter by the projection (in feet) of
the common rafter overhang:
along the ridge cut line, as shown, and measure off
one-half the thickness of the hip rafter along the blade.
Shift the tongue to the mark, set the square to the cut of
the rafter (17 inches and 8 inches), and draw the plumb
line marked “A” in the figure. Then, turn the rafter
edge-up, draw an edge centerline, and draw in the angle
of the side cut, as indicated in the lower view of figure
2-33. For a hip rafter to be framed against the ridge, there
will be only a single side cut, as indicated by the dotted
line in the figure. For one to be framed against the ridge
ends of the common rafters, there will be a double side
cut, as shown in the figure. The tail of the rafter must
have a double side cut at the same angle, but in the
reverse direction.
3. Add this product to the theoretical rafter length.
The overhang may also be stepped off as described
earlier for a common rafter. When stepping off the
length of the overhang, set the 17-inch mark on the blade
of the square even with the edge of the rafter. Set the
unit of rise, whatever it might be, on the tongue even
with the same rafter edge.
The angle of the side cut on a hip rafter may also be
laid out by referring to the unit length rafter table on the
framing square. (Look ahead to figure 2-41.) You will
see that the bottom line in the table is headed SIDE CUT
HIP OR VALLEY USE. If you follow this line over to
the column headed by the figure 8 (for a unit of rise of
8), you will find the figure 10 7/8. If you place the
framing square faceup on the rafter edge with the tongue
Rafter Side Cuts
Since a common rafter runs at 90° to the ridge, the
ridge end of a common rafter is cut square, or at 90° to
the lengthwise line of the rafter. A hip rafter, however,
joins the ridge, or the ridge ends of the common rafter,
at other than a 90° angle, and the ridge end of a hip rafter
must therefore be cut to a corresponding angle, called a
side cut. The angle of the side cut is more acute for a
high rise than it is for a low one.
on the ridge-end cut line, and set the square to a cut of
10 7/8 inches on the blade and 12 inches on the tongue,
you can draw the correct side-cut angle along the
The angle of the side cut is laid out as shown in
figure 2-33. Place the tongue of the framing square
Figure 2-34.-Backing or dropping a hip rafter: A. Marking the top (plumb) cut and the seat (level) cut of a hip rafter; B. Determining
amount of backing or drop; C. Bevel line for backing the rafter; D. Deepening the bird’s-mouth for dropping the rafter.
line down from the top edge of the rafter a distance equal
to the same dimension on the common rafter. This must
be done so that the hip rafter, which is usually wider than
a common rafter, will be level with the common rafters.
Laying out the bird’ s-mouth for a hip rafter is much
the same as for a common rafter. However, there are a
couple of things to remember. When the plumb (heel)
cut and level (seat) cut lines are laid out for a
bird’s-mouth on a hip rafter, set the body of the square
at 17 inches and the tongue to the unit of rise (for
example, 8 inches-depending on the roof pitch)
(fig. 2-34, view A). When laying out the depth of the
heel for the bird’s-mouth, measure along the heel plumb
If the bird’s-mouth on a hip rafter has the same depth
as the bird’s-mouth on a common rafter, the edge of the
hip rafter will extend above the upper ends of the jack
rafters. You can correct this by either backing or
dropping the hip rafter. Backing means to bevel the top
edges of the hip rafter (see fig. 2-35). The amount of
backing is taken at a right angle to the roof surface on
mark and parallel to the edge (view C) indicates the
bevel angle if the rafter is to be backed. The
perpendicular distance between the line and the edge of
the rafter is the amount of the drop. This represents the
amount the depth of the hip rafter bird’s-mouth should
exceed the depth of the common rafter bird’s-mouth
(view D).
An intersecting roof, also known as a combination
roof, consists of two or more sections sloping in
different directions. A valley is formed where the
different sections come together.
The two sections of an intersecting roof mayor may
not be the same width. If they are the same width, the
roof is said to have equal spans. If they are not the same
width, the roof is said to have unequal spans.
Figure 2-35.-Backing or dropping a hip rafter.
the top edge of the hip rafters. Dropping means to
deepen the bird’s-mouth so as to bring the top edge of
the hip rafter down to the upper ends of the jacks. The
amount of drop is taken on the heel plumb line (fig. 2-34,
view D).
In a roof with equal spans, the height (total rise) is
the same for both ridges (fig. 2-36). That is, both
sections are the same width, and the ridgeboards are the
same height. A pair of valley rafters is placed where the
slopes of the roof meet to form a valley between the two
sections. These rafters go from the inside corners
formed by the two sections of the building to the corners
The backing or drop required is calculated, as
shown in figure 2-34, view B. Set the framing square to
the cut of the rafter (8 inches and 17 inches) on the upper
edge, and measure off one-half the thickness of the rafter
from the edge along the blade. A line drawn through this
Figure 2-36.-Intersecting roof with equal spans.
Figure 2-37.—Intersecting roof with unequal spans.
roofs, but they are quite rare and require special framing
formed by the intersecting ridges. Valley jack rafters run
from the valley rafters to both ridges. Hip-valley cripple
jack rafters are placed between the valley and hip rafters.
In the discussion of valley rafter layout, it is
assumed that the roof is equal pitch. Also, the unit of run
and unit of rise of an addition or dormer common rafter
are assumed to be the same as the unit of run and rise of
a main-roof common rafter. In an equal-pitch roof, the
valley rafters always run at 45° to the building lines and
the ridge pieces.
An intersecting roof with unequal spans requires a
supporting valley rafter to run from the inside corner
formed by the two sections of the building to the main
ridge (fig. 2-37). A shortened valley rafter runs from the
other inside comer of the building to the supporting
valley rafter. Like an intersecting roof with equal spans,
one with unequal spans also requires valley jack rafters
and hip-valley cripple jack rafters. In addition, a valley
cripple jack rafter is placed between the supporting and
shortened valley rafters. Note that the ridgeboard is
lower on the section with the shorter span.
Figure 2-38 shows an equal-span framing situation,
in which the span of the addition is the same as the span
of the main roof. Since the pitch of the addition roof is
the same as the pitch of the main roof, equal spans bring
the ridge pieces to equal heights.
Looking at the roof framing diagram in the figure,
you can see the total run of a valley rafter (indicated by
AB and AC in the diagram) is the hypotenuse of a right
triangle with the altitude and base equal to the total run
of a common rafter in the main roof. The unit of run of
a valley rafter is therefore 16.97, the same as the unit of
run for a hip rafter. It follows that figuring the length of
an equal-span valley rafter is the same as figuring the
length of an equal-pitch hip roof hip rafter.
Valley Rafters
Valley rafters run at a 45° angle to the outside walls
of the building. This places them parallel 10 the hip
rafters. Consequently, they are the same length as the
hip rafters.
A valley rafter follows the line of intersection
between a main-roof surface and a gable-roof addition
or a gable-roof dormer surface. Most roofs having
valley rafters are equal-pitch roofs, in which the pitch
of the addition or dormer roof is the same as the pitch
of the main roof. There are unequal-pitch valley-rafter
A valley rafter, however, does not require backing
or dropping. The projection, if any, is figured just as it
is for a hip rafter. Side cuts are laid out as they are for a
Figure 2-38.-Equal-span intersecting roof.
Figure 2-40.-Equal pitch but unequal span framing.
Figure 2-40 shows a framing situation in which the
span of the addition is shorter than the span of the main
roof. Since the pitch of the addition roof is the same as
the pitch of the main roof, the shorter span of the
addition brings the addition ridge down to a lower level
than that of the main-roof ridge.
There are two ways of framing an intersection of
this type. In the method shown in figure 2-40, a fulllength valley rafter (AD in the figure) is framed between
the top plate and the main-roof ridgeboard. A shorter
valley rafter (BC in the figure) is then framed to the
longer one. If you study the framing diagram, you can
see that the total run of the longer valley rafter is the
hypotenuse of a right triangle with the altitude and base
equal to the total run of a common rafter in the main
roof. The total run of the shorter valley rafter, on the
other hand, is the hypotenuse of a right triangle with the
altitude and base equal to the total run of a common
rafter in the addition. The total run of a common rafter
in the main roof is equal to one-half the span of the main
roof. The total run of a common rafter in the addition is
equal to one-half the span of the addition.
Figure 2-39.-Ridge-end shortening allowance for equal-span
intersecting valley rafter.
hip rafter. The valley-rafter tail has a double side cut
(like the hip-rafter tail) but in the reverse direction. This
is because the tail cut on a valley rafter must form an
inside, rather than an outside, corner. As indicated in
figure 2-39, the ridge-end shortening allowance in this
framing situation amounts to one-half of the 45°
thickness of the ridge.
Knowing the total run of a valley rafter, or of any
rafter for that matter, you can always find the line length
by applying the bridge measure times the total run.
Figure 2-41.-Rafter table method.
of the addition. Since one-half the span of the addition
is 15 feet, the length of the shorter valley rafter is
Suppose, for example, that the span of the addition in
figure 2-40 is 30 feet and that the unit of rise of a
common rafter in the addition is 9. The total run of the
shorter valley rafter is:
15 x 9.21 = 288.15 inches, or approximately 24.01 feet.
Figure 2-42 shows the long and short valley rafter
shortening allowances. Note that the long valley rafter
has a single side cut for framing to the main-roof ridge
piece, whereas the short valley rafter is cut square for
framing to the long valley rafter.
Figure 2-43 shows another method of framing an
equal-pitch unequal-span addition. In this method, the
inboard end of the addition ridge is nailed to a piece that
hangs from the main-roof ridge. As shown in the
framing diagram, this method calls for two short valley
rafters (AB and AC), each of which extends from the
top plate to the addition ridge.
Referring to the unit length rafter table in figure
2-41, you can see the bridge measure for a valley rafter
in a roof with a common rafter unit of rise of 9 is 19.21.
Since the unit of run of a valley rafter is 16.97, and the
total run of this rafter is 21.21 feet, the line length must
be the value of x in the proportional equation
16.97:19.21::21.21:x, or 24.01 feet.
An easier way to find the length of a valley rafter is
to multiply the bridge measure by the number of feet in
one-half the span of the roof. The length of the longer
valley rafter in figure 2-40, for example, would be 19.21
times one-half the span of the main roof. The length of
the shorter valley rafter is 19.21 times one-half the span
Figure 2-43.-Another method of framing equal-pitch unequalspan intersection.
Figure 2-42.-Long and short valley rafter shortening allowance.
Figure 2-46.—Arrangement and names of framing members
for dormer without sidewalls.
Figure 2-44.-Shortening allowance of valley rafters suspended
ridge method of intersecting roof framing.
Figure 2-47.—Valley rafter shortening allowance for dormer
without sidewalls.
As indicated in figure 2-44, the shortening
allowance of each of the short valley rafters is one-half
the 45° thickness of the addition ridge. Each rafter is
framed to the addition ridge with a single side cut.
Figure 2-45 shows a method of framing a gable
dormer without sidewalls. The dormer ridge is framed
to a header set between a pair of doubled main-roof common rafters. The valley rafters (AB and AC) are framed
between this header and a lower header. As indicated in
the framing diagram, the total run of a valley rafter is
the hypotenuse of a right triangle with the shorter sides
equal to the total run of a common rafter in the dormer.
Figure 2-46 shows the arrangement and names of
framing members in this type of dormer framing.
The upper edges of the header must be beveled to
the cut of the main roof. Figure 2-47 shows that in this
Figure 2-45.—Method of framing dormer without sidewalk.
Figure 2-49.-Valley rafter shortening allowance for dormers
with sidewalls.
Figure 2-48.—Method of framing gable dormer with sidewalls.
method of framing, the shortening allowance for the
upper end of a valley rafter is one-half the 45° thickness
of the inside member in the upper doubled header. There
is also a shortening allowance for the lower end,
consisting of one-half the 45° thickness of the inside
member of the doubled common rafter. The figure also
shows that each valley rafter has a double side cut at the
upper and lower ends.
Figure 2-50.-Types of jack rafters.
Figure 2-48 shows a method of framing a gable
Jack Rafters
dormer with sidewalls. As indicated in the framing
diagram, the total run of a valley rafter is again the
hypotenuse of a right triangle with the shorter sides each
equal to the run of a common rafter in the dormer. You
figure the lengths of the dormer corner posts and side
studs just as you do the lengths of gable-end studs, and
you lay off the lower end cutoff angle by setting the
square to the cut of the main roof.
A jack rafter is a part of a common rafter, shortened
for framing a hip rafter, a valley rafter, or both. This
means that, in an equal-pitch framing situation, the unit
of rise of a jack rafter is always the same as the unit of
rise of a common rafter. Figure 2-50 shows various types
of jack rafters.
A hip jack rafter extends from the top plate to a hip
rafter. A vane y jack rafter extends from a valley rafter
to a ridge. (Both are shown in fig. 2-51.) A cripple jack
rafter does not contact either a top plate or a ridge. A
Figure 2-49 shows the valley rafter shortening
allowance for this method of framing a dormer with
Figure 2-51.—Valley cripple Jack and hip-valley cripple jack.
valley cripple jack extends between two valley rafters
in the long and short valley rafter method of framing. A
hip-valley cripple jack extends from a hip rafter to a
valley rafter.
LENGTHS.— Figure 2-52 shows a roof framing
diagram for a series of hip jack rafters. The jacks are
always on the same OC spacing as the common rafters.
Now, suppose the spacing, in this instance, is 16
inches OC. You can see that the total run of the shortest
jack is the hypotenuse of a right triangle with the shorter
sides each 16 inches long. The total run of the shortest
jack is therefore:
Figure 2-52.—Hip jack framing diagram.
rafter table on the framing square for unit of rise ranging
from 2 to 18, inclusive. Turn back to figure 2-41, which
shows a segment of the unit length rafter table. Note the
third line in the table, which reads DIFF IN LENGTH
OF JACKS 16 INCHES CENTERS. If you follow this
line over to the figure under 8 (for a unit of rise of 8),
you’ll find the same unit length (19.23) that you worked
out above.
Suppose that a common rafter in this roof has a unit
of rise of 8. The jacks have the same unit of rise as a
common rafter. The unit length of a jack in this roof is:
This means that a jack is 14.42 units long for every
12 units of run. The length of the shortest hip jack in
this roof is therefore the value of x in the proportional
equation 12:14.42::16:x, or 19.23 inches.
The best way to determine the length of a valley jack
or a cripple jack is to apply the bridge measure to the
total run. The bridge measure of any jack is the same as
the bridge measure of a common rafter having the same
unit of rise as the jack. Suppose the jack has a unit of
rise of 8. In figure 2-41, look along the line on the unit
length rafter tables headed LENGTH COMMON
RAFTER PER FOOT RUN for the figure in the column
under 8; you’ll find a unit length of 14.42. You should
know by this time how to apply this to the total run of a
jack to get the line length.
This is always the length of the shortest hip jack
when the jacks are spaced 16 inches OC and the
common rafter in the roof has a unit of rise of 8. It is also
the common difference of jacks, meaning that the next
hip jack will be 2 times 19.23 inches.
The common difference for hip jacks spaced 16
inches OC, or 24 inches OC, is given in the unit length
The best way to figure the total runs of valley jacks
and cripple jacks is to lay out a framing diagram and
study it to determine what these runs must be. Figure
2-53 shows part of a framing diagram for a main hip roof
with a long and short valley rafter gable addition. By
studying the diagram, you can figure the total runs of
the valley jacks and cripple jacks as follows:
l The run of valley jack No. 1 is obviously the same
as the run of hip jack No. 8, which is the run of
the shortest hip jack. The length of valley jack
No. 1 is therefore equal to the common difference
of jacks.
l The run of valley jack No. 2 is the same as the
run of hip jack No. 7, and the length is therefore
twice the common difference of jacks.
l The run of valley jack No. 3 is the same as the
run of hip jack No. 6, and the length is therefore
three times the common difference of jacks.
Figure 2-53.—Jack rafter framing diagram.
l The run of hip-valley cripple Nos. 4 and 5 is the
same as the run of valley jack No. 3.
Figure 2-54.-Line and actual lengths of hip roof ridgeboard.
includes any overhang. For a hip main roof, however,
the ridge layout requires a certain amount of calculation.
l The run of valley jack Nos. 9 and 10 is equal to
the spacing of jacks OC. Therefore, the length of
one of these jacks is equal to the common
difference of jacks.
As previously mentioned, in an equal-pitch hip roof,
the line length of the ridge amounts to the length of the
building minus the span. The actual length depends
upon the way the hip rafters are framed to the ridge.
l The run of valley jacks Nos. 11 and 12 is twice
the run of valley jacks Nos. 9 and 10, and the
length of one of these jacks is therefore twice the
common difference of jacks.
As indicated in figure 2-54, the line length ends of
the ridge are at the points where the ridge centerline and
the hip rafter center line cross. In the figure, the hip rafter
is framed against the ridge. In this method of framing,
the actual length of the ridge exceeds the line length, at
each end, by one-half the thickness of the ridge, plus
one-half the 45° thickness of the hip rafter. In the figure,
the hip rafter is also framed between the common
rafters. In this method of framing, the actual length of
the ridge exceeds the line length at each end by one-half
the thickness of a common rafter.
l The run of valley cripple No. 13 is twice the
spacing of jacks OC, and the length is therefore
twice the common difference of jacks.
l The run of valley cripple No. 14 is twice the run
of valley cripple No. 13, and the length is therefore four times the common difference of jacks.
has a shortening allowance at the upper end, consisting
of one-half the 45° thickness of the hip rafter. A valley
jack rafter has a shortening allowance at the upper end,
consisting of one-half the 45° thickness of the ridge, and
another at the lower end, consisting of one-half the 45°
thickness of the valley rafter. A hip-valley cripple has a
shortening allowance at the upper end, consisting of
one-half the 45° thickness of the hip rafter, and another
at the lower end, consisting of one-half the 45° thickness
of the valley rafter. A valley cripple has a shortening
allowance at the upper end, consisting of one-half the
45° thickness of the long valley rafter, and another at the
lower end, consisting of one-half the 45° thickness of
the short valley rafter.
Figure 2-55, view A, shows that the length of the
ridge for an equal-span addition is equal to the length of
the addition top plate, plus one-half the span of the
building, minus the shortening allowance at the
SIDE CUTS.— The side cut on a jack rafter can be
laid out using the same method as for laying out the side
cut on a hip rafter. Another method is to use the fifth line
of the unit length rafter table, which is headed SIDE
CUT OF JACKS USE (fig. 2-41). If you follow that line
over to the figure under 8 (for a unit of rise of 8), you
will see that the figure given is 10. To lay out the side
cut on a jack set the square faceup on the edge of the
rafter to 12 inches on the tongue and 10 inches on the
blade, and draw the side-cut line along the tongue.
rafter is a shortened common rafter; consequently, the
bird’s-mouth and projection on a jack rafter are laid out
just as they are on a common rafter.
Ridge Layout
Laying out the ridge for a gable roof presents no
particular problem since the line length of the ridge is
equal to the length of the building. The actual length
Figure 2-55.—Lengths of addition ridge.
Figure 2-57.-Shed roof framing.
Figure 2-56, view A, shows that the length of the
ridge on a dormer without sidewalls is equal to one-half
the span of the dormer, less a shortening allowance
one-half the thickness of the inside member of the upper
double header. View B shows that the length of the ridge
on a dormer with sidewalls is the length of the dormer
rafter plate, plus one-half the span of the dormer, minus
a shortening allowance one-half the thickness of the
inside member of the upper double header.
A shed roof is essentially one-half of a gable roof.
Like the full-length rafters in a gable roof, the full-length
rafters in a shed roof are common rafters. However, the
total run of a shed roof common rafter is equal to the
span of the building minus the width of the top plate on
the higher rafter-end wall (fig. 2-57). Also, the run of
the overhang on the higher wall is measured from the
inner edge of the top plate. With these exceptions, shed
roof common rafters are laid out like gable roof common
rafters. A shed roof common rafter has two bird’smouths, but they are laid out just like the bird’s-mouth
on a gable roof common rafter.
Figure 2-56.-Lengths of dormer ridge.
main-roof ridge. The shortening allowance amounts to
one-half the thickness of the main-roof ridge.
View B shows that the length of the ridge for an
unequal-span addition varies with the method of
framing the ridge. If the addition ridge is suspended
from the main-roof ridge, the length is equal to the
length of the addition top plate, plus one-half the span
For a shed roof, the height of the higher rafter-end
wall must exceed the height of the lower by an amount
equal to the total rise of a common rafter.
of the building. If the addition ridge is framed by the
long and short valley rafter method, the length is equal
to the length of the addition top plate, plus one-half the
addition ridge is framed to a double header set between
a couple of double main-roof common rafters, the length
of the ridge is equal to the length of the addition sidewall
rafter plate, plus one-half the span of the addition, minus
Figure 2-58 shows a method of framing a shed
dormer. This type of dormer can be installed on almost
any type of roof. There are three layout problems to be
solved here: determining the total run of a dormer rafter;
determining the angle of cut on the inboard ends of the
dormer rafters; and determining the lengths of the
dormer sidewall studs.
a shortening allowance one-half the thickness of the
inside member of the double header.
To determine the total run of a dormer rafter, divide
the height of the dormer end wall, in inches, by the
span of the addition, minus a shortening allowance
one-half the 45° thickness of the long valley rafter. If the
Figure 2-58.-Method of framing a shed dormer.
difference between the unit of rise of the dormer roof
and the unit of rise of the main roof. Take the dormer
shown in figure 2-59, for example. The height of the
dormer end wall is 9 feet, or 108 inches. The unit of rise
of the main roof is 8; the unit of rise of the dormer roof
is 2 1/2; the difference is 5 1/2. The total run of a dormer
rafter is therefore 108 divided by 5 1/2, or 19.63 feet.
Knowing the total run and the unit of rise, you can figure
the length of a dormer rafter by any of the methods
already described.
Figure 2-59.-Shed dormer framing calculation.
As indicated in figure 2-59, the inboard ends of the
dormer rafters must be cut to fit the slope of the main
roof. To get the angle of this cut, set the square on the
rafter to the cut of the main roof, as shown in the bottom
view of figure 2-59. Measure off the unit of rise of the
dormer roof from the heel of the square along the tongue
as indicated and make a mark at this point. Draw the
cutoff line through this mark from the 12-inch mark.
roof. To get the upper end cutoff angle, set the square to
the cut of the dormer roof.
Rafter locations are laid out on wall plates and
ridgeboards with matching lines and marked with X’s,
as used to lay out stud and joist locations. For a gable
roof, the rafter locations are laid out on the rafter plates
first. The locations are then transferred to the ridge by
matching the ridge against a rafter plate.
You figure the lengths of the sidewall studs on a
shed dormer as follows: In the roof shown in figure 2-59,
a dormer rafter raises 2 1/2 units for every 12 units of
run. A main-roof common rafter rises 8 units for every
12 units of run. If the studs were spaced 12 inches OC,
the length of the shortest stud (which is also the common
difference of studs) would be the difference between
8 and 2 1/2 inches, or 5 1/2 inches. If the stud spacing
is 16 inches, the length of the shortest stud is the value
of x in the proportional equation 12:5 1/2::16:x,
or 7 5/16 inches. The shortest stud, then, will be
7 5/16 inches long. To get the lower end cutoff angle for
studs, set the square on the stud to the cut of the main
Rafter Locations
The rafter plate locations of the ridge-end common
rafters in an equal-pitch hip roof measure one-half of the
span (or the run of a main-roof common rafter) away
from the building comers. These locations, plus the
rafter plate locations of the rafters lying between the
ridge-end common rafters, can be transferred to the
ridge by matching the ridgeboads against the rafter
tables. Let’s suppose that the common rafter unit of rise
is 8. In that case, the unit length of a valley rafter is 18.76.
The total run of the longer valley rafter between the
shorter rafter tie-in and the rafter plate is the hypotenuse
of a right triangle with the altitude and base equal to
one-half of the span of the addition. Suppose the
addition is 20 feet wide. Then, the total run is:
You know that the valley rafter is 18.76 units long
for every 16.97 units of run. The length of rafter for
14.14 feet of run must therefore be the value of x in
the proportional equation 16.97:18.76::14.14:x, or
15.63 feet. The location mark for the inboard end of the
shorter valley rafter on the longer valley rafter, then, will
be 15.63 feet, or 15 feet 7 9/16 inches, from the heel
plumb cut line on the longer valley rafter. The length of
the additional ridge will be equal to one-half the span of
the addition, plus the length of the additional sidewall
top plate, minus a shortening allowance one-half the 45°
thickness of the longer valley rafter.
If framing is by the suspended ridge method, the
distance between the suspension point on the main-roof
and the end of the main-roof ridge is equal to distance
A plus distance C. Distance C is one-half the span of the
addition. The distance between the point where the
inboard ends of the valley rafters (both short in this
method of framing) tie into the addition ridge and the
outboard end of the ridge is equal to one-half the span
of the addition, plus the length of the additional ridge
(which is equal to one-half of the span of the main roof),
plus the length of the addition sidewall rafter plate.
Figure 2-60.-Intersection ridge and valley rafter location
The locations of additional ridge and valley rafters
can be determined as indicated in figure 2-60. In an
equal-span situation (views A and B), the valley rafter
locations on the main-roof ridge lie alongside the
addition ridge location. In view A, the distance between
the end of the main-roof ridge and the addition ridge
location is equal to A plus distance B, distance B being
one-half the span of the addition. In view B, the distance
between the line length end of the main-roof ridge and
the addition ridge location is the same as distance A. In
both cases, the line length of the addition ridge is equal
to one-half the span of the addition, plus the length of
the addition sidewall rafter plate.
Figure 2-60, view C, shows an unequal-span
situation. If framing is by the long and short valley rafter
method, the distance from the end of the main-roof ridge
to the upper end of the longer valley rafter is equal to
distance A plus distance B, distance B being one-half the
span of the main roof. To determine the location of the
inboard valley rafter, first calculate the unit length of the
longer valley rafter, or obtain it from the unit length rafter
Roof Frame Erection
Roof framing should be done from a scaffold with
planking not less than 4 feet below the level of the
main-roof ridge. The usual type of roof scaffold consists
of diagonally braced two-legged horses, spaced about
10 feet apart and extending the full length of the ridge.
If the building has an addition, as much as possible
of the main roof is framed before the addition framing
is started. Cripples and jack rafters are usually left out
until after the headers, hip rafters, valley rafters, and
ridges to which they will be framed have been installed.
For a gable roof, the two pairs of gable-end rafters and
the ridge are usually erected first.
Two crewmembers, one at each end of the scaffold,
hold the ridge in position. Another crewmember sets the
gable-end rafters in place and toenails them at the rafter
plate with 8d nails, one on each side of a rafter. Before
we proceed any further, see table 2-1 as to the type and
Table 2-1.—Recommended Schedule for Nailing the Framing and Sheathing of a Wood-Frame Structure
Table 2-1.-Recommended Schedule for Nailing the Framing and Sheathing of a Wood-Frame Structure—Continued
top edge of the jack should contact the centerline of the
valley rafter, as shown.
size nails used in roof framing erection. Each crewmember on the scaffold then end-nails the ridge to the
end of the rafter. They then toenail the other rafter to the
ridge and to the first rafter with two 10d nails, one on
each side of the rafter.
Temporary braces, like those for a wall, should be
set up at the ridge ends to hold the rafter approximately
plumb, after which the rafters between the end rafters
should be erected. The braces should then be released,
and the pair of rafters at one end should be plumbed with
a plumb line, fastened to a stick extended from the end
of the ridge. The braces should then be reset, and they
should be left in place until enough sheathing has been
installed to hold the rafters plumb. Collar ties, if any, are
nailed to common rafters with 8d nails, three to each end
of a tie. Ceiling-joist ends are nailed to adjacent rafters
with 10d nails.
On a hip roof, the ridge-end common rafters and
ridges are erected first, in about the same manner as for
a gable roof. The intermediate common rafters are then
filled in. After that, the ridge-end common rafters
extending from the ridge ends to the midpoints on the
end walls are erected. The hip rafters and hip jacks are
installed next. The common rafters in a hip roof do not
require plumbing. When correctly cut and installed, hip
rafters will bring the common rafters to plumb. Hip
rafters are toe nailed to plate comers with 10d nails. Hip
jacks are toe nailed to hip rafters with 10d nails.
For an addition or dormer, the valley rafters are
usually erected first. Valley rafters are toe nailed with
10d nails. Ridges and ridge-end common rafters are
erected next, other addition common rafters next, and
valley and cripple jacks last. A valley jack should be held
in position for nailing, as shown in figure 2-61. When
properly nailed, the end of a straightedge laid along the
this section, you should be able to describe the
types and parts of roof trusses, and explain
procedures for fabricating, handling, and
erecting them.
Roof truss members are usually connected at the
joints by gussets. Gussets are made of boards, plywood,
or metal. They are fastened to the truss by nails, screws,
bolts, or adhesives. A roof truss is capable of supporting
loads over a long span without intermediate supports.
Figure 2-61.-Correct position for nailing a valley jack rafter.
Figure 2-62.—Truss construction.
Roof trusses save material and on-site labor costs.
It is estimated that a material savings of about 30 percent
is made on roof members and ceiling joists. When you
are building with trusses, the double top plates on
interior partition walls and the double floor joists under
interior bearing partitions are not necessary. Roof
trusses also eliminate interior bearing partitions because
trusses are self-supporting.
The basic components of a roof truss are the top and
bottom chords and the web members (fig. 2-62). The top
chords serve as roof rafters. The bottom chords act as
ceiling joists. The web members run between the top and
bottom chords. The truss parts are usually made of 2- by
4-inch or 2- by 6-inch material and are tied together with
metal or plywood gusset plates. Gussets shown in this
figure are made of plywood.
buildings require this type of truss. Generally, the slope
of the bottom chord of a scissor truss equals one-half the
slope of the top chord.
A roof truss is an engineered structural frame resting
on two outside walls of a building. The load carried by
the truss is transferred to these outside walls.
Weight and Stress
The design of a truss includes consideration of snow
and wind loads and the weight of the roof itself. Design
also takes into account the slope of the roof. Generally,
the flatter the slope, the greater the stresses. Flatter
slopes, therefore, require larger members and stronger
connections in roof trusses.
Roof trusses come in a variety of shapes. The ones
most commonly used in light framing are the king post,
the W-type (or fink), and the scissors. An example of
each is shown in figure 2-63.
King Post
The simplest type of truss used in frame construction is the king-post truss. It consists of top and
bottom chords and a vertical post at the center.
W-Type (Fink)
The most widely used truss in light-frame construction is the W-type (fink) truss. It consists of top and
bottom chords tied together with web members. The
W-type truss provides a uniform load-carrying capacity.
The scissor truss is used for building with sloping
ceilings. Many residential, church, and commercial
Figure 2-63.—Truss types.
Figure 2-64.-Plywood gussets.
Figure 2-65.-Metal gusset plates.
Figure 2-66.-Truss members fastened together with split-ring connectors.
points D and E. This gives the bottom chord support
along the outside wall span. The weight of the bottom
chord has a pulling-apart effect (tension) on the long
A great majority of the trusses used are fabricated
with plywood gussets (fig. 2-64, views A through E),
nailed, glued, or bolted in place. Metal gusset plates (fig.
2-65) are also used. These are flat pieces usually
manufactured from 20-gauge zinc-coated or galvanized
steel. The holes for the nails are prepunched. Others are
assembled with split-ring connectors (fig. 2-66) that
prevent any movement of the members. Some trusses
are designed with a 2- by 4-inch soffit return at the end
of each upper chord to provide nailing for the soffit of
a wide box cornice.
In view C, the short webs run from the intermediate
points F and G of the top chord to points D and E of the
bottom chord. Their purpose is to provide support to the
top chord. This exerts a downward, pushing-together
force (compression) on the short web.
Tension and Compression
Each part of a truss is in a state of either tension or
compression (see fig. 2-67). The parts in a state of
tension are subjected to a pulling-apart force. Those
under compression are subjected to a pushing-together
force. The balance of tension and compression gives the
truss its ability to carry heavy loads and cover wide
In view A of figure 2-67, the ends of the two top
chords (A-B and A-C) are being pushed together
(compressed). The bottom chord prevents the lower
ends (B and C) of the top chords from pushing out;
therefore, the bottom chord is in a pulling-apart state
(tension). Because the lower ends of the top chords
cannot pull apart, the peak of the truss (A) cannot drop
In view B, the long webs are secured to the peak of
the truss (A) and also fastened to the bottom chord at
Figure 2-67.—Tension and compression in a truss.
In view D, you can see that the overall design of the
truss roof transfers the entire load (roof weight, snow
load, wind load, and so forth) down through the outside
walls to the foundation.
Web members must be fastened at certain points
along the top and bottom chords in order to handle the
stress and weight placed upon the truss. A typical layout
for a W-type (fink) truss is shown in figure 2-68. The
points at which the lower ends of the web members
fasten to the bottom chord divide the bottom chord into
Figure 2-68.-Layout for a W-type (fink) truss.
Figure 2-69.—Placing trusses by hand.
three equal parts. Each short web meets the top chord at
a point that is one-fourth the horizontal distance of the
bottom chord.
distances between connections are shorter, the W-truss
can span up to 32 feet without intermediate support, and
its members can be made of lower grade lumber.
The construction features of a typical W-truss are
shown in figure 2-64. Also shown are gusset cutout sizes
and nailing patterns for nail-gluing. The span of this
truss is 26 feet and roof cut is 4/12. When spaced
24 inches apart and made of good- quality 2- by 4-inch
members, the trusses should be able to support a total
roof load of 40 pounds per square foot.
Trusses are usually spaced 24 inches OC. They must
be lifted into place, fastened to the walls, and braced.
Small trusses can be placed by hand, using the procedure
shown in figure 2-69. Builders are required on the two
opposite walls to fasten the ends of the trusses. One or
two workers on the floor below can push the truss to an
upright position. If appropriate equipment is available,
use it to lift trusses into place.
Gussets for light wood trusses are cut from 3/8- or
1/2-inch standard plywood with an exterior glue line, or
from sheathing-grade exterior plywood. Glue is spread
on the clean surfaces of the gussets and truss members.
Staples are used to supply pressure until the glue is set.
Under normal conditions and where the relative
humidity of air in attic spaces tends to be high, a
resorcinol glue is applied. In areas of low humidity, a
casein or similar glue is used. Two rows of 4d nails
are used for either the 3/8- or 1/2-inch-thick gusset. The
nails are spaced so that they are 3 inches apart and
3/4 inches from the edges of the truss members. Gussets
are nail-glued to both sides of the truss.
In handling and storing completed trusses, avoid
placing unusual stresses on them. They were designed
to carry roof loads in a vertical position; thus it is
important that they be lifted and stored upright. If they
must be handled in a flat position, enough support
should be used along their length to minimize bending
deflections. Never support the trusses only at the center
or only at each end when they are in a flat position.
Plywood-gusset, king-post trusses are limited to
spans of 26 feet or less if spaced 24 inches apart and
fabricated with 2- by 4-inch members and a 4/12 roof
cut. The spans are somewhat less than those allowed for
W-trusses having the same-sized members. The shorter
span for the king-post truss is due, in part, to the
unsupported upper chord. On the other hand, because it
has more members than the king-post truss and
After the truss bundles have been set on the walls,
they are moved individually into position, nailed down,
and temporarily braced. Without temporary bracing, a
truss may topple over, cause damage to the truss, and
possibly injure workers. A recommended procedure for
bracing trusses as they are being set in place is shown
in figure 2-70. Refer to the figure as you study the
following steps:
Figure 2-70.—Installing roof trusses and temporary bracing.
Figure 2-71.—Permanent lateral bracing in a truss.
Step 1.
Position the first roof truss. Fasten it to the
double top plate with toenails or metal
anchor brackets. A 2- by 2-inch backer
piece is sometimes used for additional
Step 2.
Fasten two 2 by 4 braces to the roof truss.
Drive stakes at the lower ends of the two
braces. Plumb the truss and fasten the
lower ends of the braces to the stakes
driven into the ground.
Step 3.
Position the remaining roof trusses. As
each truss is set in place, fasten a lateral
brace to tie it to the preceding trusses. Use
1 by 4 or 2 by 4 material for lateral braces.
They should overlap a minimum of three
trusses. On larger roofs, diagonal bracing
should be placed at 20-foot intervals.
Figure 2-72.—Fastening trusses to the plate: A. Toenailing;
B. Metal bracket.
The temporary bracing is removed as the roof
sheathing is nailed. Properly nailed plywood sheathing
is sufficient to tie together the top chords of the trusses.
Permanent lateral bracing of 1- by 4-inch material is
recommended at the bottom chords (fig. 2-71). The
braces are tied to the end walls and spaced 10 feet OC.
in nailing the lower chord to the plate. Predrilling may
be necessary to prevent splitting. Because of the
single-member thickness of the truss and the presence
of gussets at the wall plates, it is usually a good idea to
use some type of metal connector to supplement the
The same types of metal anchors (fig. 2-72, view B)
used to tie regular rafters to the outside walls are equally
effective for fastening the ends of the truss. The brackets
are nailed to the wall plates at the side and top with 8d
nails and to the lower chords of the truss with 6d or
1 1/2-inch rooting nails.
Anchoring Trusses
When fastening trusses, you must consider
resistance to uplift stresses as well as thrust. Trusses are
fastened to the outside walls with nails or framing
anchors. The ring-shank nail provides a simple
connection that resists wind uplift forces. Toe nailing is
sometimes done, but this is not always the most
satisfactory method. The heel gusset and a plywood
gusset or metal gusset plate are located at the wall plate
and make toenailing difficult. However, two 10d nails
on each side of the truss (fig. 2-72, view A) can be used
Where partitions run parallel to, but between, the
bottom truss chords, and the partitions are erected before
the ceiling finish is applied, install 2- by 4-inch blocking
Figure 2-73.-Construction details for partitions that run
parallel to the bottom truss chords.
Figure 2-74.-Construction details for partitions that run at
right angles to the bottom of the truss chords.
between the lower chords (fig. 2-73). This blocking
should be spaced not over 4 feet OC. Nail the blocking
to the chords with two 16d nails in each end. To provide
2- by 6-inch blocking on top of the partition plates
between the trusses (fig. 2-74).
nailing for lath or wallboard, nail a 1- by 6-inch or 2- by
6-inch continuous backer to the blocking. Set the bottom
face level with the bottom of the lower truss chords.
Although the following reference
was current when this TRAMAN was
published, its continued currency
cannot be assured. You therefore need
to ensure that you are studying the
latest revision.
When partitions are erected tier the ceiling finish
is applied, 2- by 4-inch blocking is set with the bottom
edge level with the bottom of the truss chords. Nail the
blocking with two 16d nails in each end.
If the partitions run at right angles to the bottom of
the truss chords, the partitions are nailed directly to
lower chord members. For applying ceiling finish, nail
Basic Roof Framing, Benjamin Barnow, Tab Books,
Inc., Blue Ridge Summit, Pa., 1986.
The previous chapters have dealt with framing
wood structures, including joists, studs, rafters, and
other structural members. These constitute “rough
carpentry” and are the main supports of a wood-frame
structure. (Subflooring and wall and roof sheathing
strengthen and brace the frame.)
The remaining work on the structure involves
installing the nonstructural members. This work,
referred to as “finish carpentry,” includes installing the
roof covering, door and window frames, and the doors
and windows themselves. Some nonstructural members
are purely ornamental, such as casings on doors and
windows, and the moldings on cornices and inside
walls. Instillation of purely ornamental members is
known as trim carpentry.
Finish carpentry is divided into exterior and interior
finish. Exterior finish material consist of roof sheathing,
exterior trim, roof coverings, outside wall covering, and
exterior doors and windows. Exterior finish materials
are installed after the rough carpentry has been
completed. Examples of interior finish materials include
all coverings applied to the rough walls, ceilings, and
floors. We will cover these topics in a later chapter.
In this chapter, we’ll cover the exterior finishing of
roofs. In the next chapter, we’ll examine the exterior
finishing of walls.
Roof sheathing boards are generally No. 3 common
or better. These are typically softwoods, such as Doughs
fir, redwood, hemlock, western larch, fir, and spruce. If
you’re covering the roof with asphalt shingles, you
should use only thoroughly seasoned wood for the
sheating. Unseasoned wood will dry and shrink which
may cause the shingles to buckle or lift along the full
length of the sheathing board.
Nominal 1-inch boards are used for both flat and
pitched roofs. Where flat roofs are to be used for a deck
or a balcony, thicker sheathing boards are required.
Board roof sheathing, like board wall sheathing and
subflooring, can be laid either horizontally or
diagonally. Horizontal board sheathing may be closed
(laid with no space between the courses) or open (laid
with space between the courses). In areas subject to
wind-driven snow, a solid roof deck is recommended.
Roof boards used for sheathing under materials
requiring solid, continuous support must be laid closed.
This includes such applications as asphalt shingles,
composition roofing, and sheet-metal roofing. Closed
roof sheathing can also be used for wood shingles. The
boards are nominal 1 inch by 8 inches and may be
square-edged, dressed and matched, shiplapped, or
tongue and groove. Figure 3-1 shows the installation of
both closed and open lumber roof sheathing.
this section, you should be able to identify
various types of roof sheathing and describe
their installation requirements.
Roof sheathing covers the rafters or roof joists. The
roof sheathing is a structural element and, therefore, part
of the framing. Sheathing provides a nailing base for the
finish roof covering and gives rigidity and strength to
the roof framing. Lumber and plywood roof sheathing
are the most commonly used materials for pitched roofs.
Plank or laminated roof decking is sometimes used in
structures with exposed ceilings. Manufactured wood
fiber roof decking is also adaptable to exposed ceiling
Figure 3-1.-Closed and open roof sheathing.
Open sheathing can be used under wood shingles or
shakes in blizzard-free areas or damp climates. Open
sheathing usually consists of 1- by 4-inch strips with the
on-center (OC) spacing equal to the shingle weather
exposure, but not over 10 inches. (A 10-inch shingle
lapped 4 inches by the shingle above it is said to be laid
6 inches to the weather.) When applying open sheathing,
you should lay the boards without spacing to a point on
the roof above the overhang.
Plywood sheathing is applied after rafters, collar
ties, gable studs, and extra bracing (if necessary) are in
place. Make sure there are no problems with the roof
frame. Check rafters for plumb, make sure there are no
badly deformed rafters, and check the tail cuts of all the
rafters for alignment. The crowns on all the rafters
should be in one direction—up.
Figure 3-2 shows two common methods of starting
the application of sheathing at the roof eaves. In view
A, the sheathing is started flush with the tail cut of the
rafters. Notice that when the fascia is placed, the top
edge of the fascia is even with the top of the sheathing.
In view B, the sheathing overlaps the tail end of the rafter
by the thickness of the fascia material. You can see that
the edge of the sheathing is flush with the fascia.
If you choose to use the first method (view A) to
start the sheathing, measure the two end rafters the width
of the plywood panel (48 inches). From the rafter tail
ends, and using the chalk box, strike a line on the top
edge of all the rafters. If you use the second method,
Nail lumber roof sheathing to each rafter with two
8-penny (8d) nails. Joints must be made on the rafters
just as wall sheathing joints must be made over the studs.
When tongue-and-groove boards are used, joints may
be made between rafters. In no case, however, should the
joints of adjoining boards be made over the same rafter
space. Also, each board should bear on at least two rafters.
Plywood offers design flexibility, construction ease,
economy, and durability. It can be installed quickly over
large areas and provides a smooth, solid base with a
minimum number of joints. A plywood deck is equally
effective under any type of shingle or built-up roof.
Waste is minimal, contributing to the low in-place cost.
Plywood is one of the most common roof sheathing
materials in use today. It comes in 4- by 8-foot sheets in
a variety of thicknesses, grades, and qualities. For
sheathing work a lower grade called CDX is usually
used. A large area (32 square feet) can be applied atone
time. This, plus its great strength relative to other
sheathing materials, makes plywood a highly desirable
The thickness of plywood used for roof sheathing is
determined by several factors. The distance between
rafters (spacing) is one of the most important. The larger
the spacing, the greater the thickness of sheathing that
should be used. When 16-inch OC rafter spacing is used,
the minimum recommended thickness is 3/8 inch. The
type of roofing material to be applied over the sheathing
also plays a role. The heavier the roof covering, the
thicker the sheathing required. Another factor
determining sheathing thickness is the prevailing
weather. In areas where there are heavy ice and snow
loads, thicker sheathing is required. Finally, you have to
consider allowable dead and live roof loads established
by calculations and tests.
These are the controlling factors in the choice of
roof sheathing materials. Recommended spans and
plywood grades are shown in table 3-1.
Figure 32.—Two methods of starting the first sheet of roof
sheathing at the eaves of a roof: A. Flush with rafter;
B. Overlapping rafter.
Table 3-1.-Plywood Roof Sheathing Application Specifications
measure the width of the panel minus the actual
thickness of the fascia material. Use this chalk line to
position the upper edge of the sheathing panels. If the
roof rafters are at right angles to the ridge and plates,
this line will place the sheathing panels parallel to the
outer ends of the rafters.
Be particularly careful when
handling sheet material on a roof
during windy conditions. You may be
thrown off balance and possibly off the
roof entirely. Also, the sheet may be
blown off the roof and strike someone.
Figure 3-3.-Plywood roofing panel installation.
Notice in figure 3-2 that sheathing is placed before
the trim is applied. Sheathing is always placed from the
lower (eaves) edge of the roof up toward the ridge. It
can be started from the left side and worked toward the
right, or you can start from the right and work toward
the left. Usually, it is started at the same end of the house
from which the rafters were laid out.
The first sheet of plywood is a full 4- by 8-foot
panel. The top edge is placed on the chalk line. If the
sheathing is started from the left side of the roof, make
sure the right end falls in the middle of a rafter. This must
be done so that the left end of the next sheet has a surface
upon which it can bear weight and be nailed.
The plywood is placed so that the grain of the top
ply is at right angles (perpendicular) to the rafters.
Placing the sheathing in this fashion spans a greater
number of rafters, spreads the load, and increases the
strength of the roof. Figure 3-3 shows plywood panels
laid perpendicular to the rafters with staggered joints.
Note that a small space is left between sheets to allow
for expansion.
The sheets that follow are butted against spacers
until the opposite end is reached. If there is any panel
hanging over the edge, it is trimmed after the panel is
fastened in place. A chalk line is snapped on the
sheathing flush with the end of the house, and the panel
is then cut with a circular saw. Read the manufacturer’s
specification stamp and allow proper spacing at the ends
and edges of the sheathing. This will compensate for any
swelling that might take place with changes in moisture
The cutoff piece of sheathing can be used to start
the second course (row of sheathing), provided it spans
two or more rafters. If it doesn’t span two rafters, start
the second course with a half sheet (4 by 4) of plywood.
It is important to stagger all vertical joints. All
horizontal joints need blocking placed underneath or a
metal clip (ply clip). Ply clips (H clips or panel clips)
are designed to strengthen the edges of sheathing panels
between supports or rafters. The use of clips is determined by the rafter spacing and specifications (see
figure 3-3).
The pattern is carried to the ridge. The final course
is fastened in place, a chalk line is snapped at the top
edge of the rafters, and the extra material cut off. The
opposite side of the roof is then sheeted using the same
When nailing plywood sheathing, follow the project
specifications for nailing procedures. Use 6d common
smooth, ring-shank or spiral thread nails for plywood
1/2 inch thick or less. For plywood more than 1/2 inch
but not exceeding 1 inch thick, use 8d common smooth,
ring-shank or spiral thread nails. When using a nail gun
for roof sheathing, follow all applicable safety
In this section, we’ll discuss the two most common
types of roof decking you will encounter as a Builder:
plank and wood fiber.
Plank roof decking, consisting of 2-inch (and
thicker) tongue-and-groove planking, is commonly
used for flat or low-pitched roofs in post-and-beam
construction. Single tongue-and-groove decking in
nominal 2 by 6 and 2 by 8 sizes is available with the
V-joint pattern only.
Decking comes in nominal widths of 4 to 12 inches
and in nominal thicknesses of 2 to 4 inches. Three- and
4-inch roof decking is available in random lengths of 6
to 20 feet or longer (odd and even).
Laminated decking is also available in several
different species of softwood lumber: Idaho white pine,
inland red cedar, Idaho white fir, ponderosa pine,
Douglas fir, larch, and yellow pine. Because of the
laminating feature, this material may have a facing of
one wood species and back and interior laminations of
different woods. It is also available with all laminations
of the same species. For all types of decking, make sure
the material is the correct thickness for the span by
checking the manufacturer’s recommendations. Special
load requirements may reduce the allowable spans.
Roof decking can serve both as an interior ceiling finish
and as a base for roofing. Heat loss is greatly reduced
by adding fiberboard or other rigid insulation over the
wood decking.
Figure 3-4.-Ends of roof decking cut at a 2° angle.
Figure 3-5.-Plank decking span arrangements.
INSTALLATION.— Roof decking applied to a flat
roof should be installed with the tongue away from the
worker. Roof decking applied to a sloping roof should
be installed with the tongue up. The butt ends of the
pieces are bevel cut at approximately a 2° angle (fig.
3-4). This provides a bevel cut from the face to the back
to ensure a tight face butt joint when the decking is laid
in a random-length pattern. If there are three or more
supports for the decking, a controlled random laying
pattern (shown in figure 3-5) can be used. This is an
economical pattern because it makes use of
random-plank lengths, but the following rules must be
planks is the most economical. Random-length double
tongue-and-groove decking is used when there are three
or more spans. It is not intended for use over single
spans, and it is not recommended for use over double
spans (see figure 3-5).
NAILING.— Fasten decking with common nails
twice as long as the nominal plank thickness. For widths
6 inches or less, toenail once and face-nail once at each
support. For widths over 6 inches, toenail once and
face-nail twice. Decking 3 and 4 inches thick must be
predrilled and toenailed with 8-inch spikes. Bright
common nails may be used, but dipped galvanized
common nails have better holding power and reduce the
possibility of rust streaks. End joints not over a support
should be side-nailed within 10 inches of each plank
end. Splines are recommended on end joints of 3- and
4-inch material for better alignment, appearance, and
l Stagger the end joints in adjacent planks as
widely as possible and not less than 2 feet.
l Separate the joints in the same general line by at
least two courses.
l Minimize joints in the middle one-third of all
l Make each plank bear on at least one support.
Wood Fiber
l Minimize the joints in the end span.
All-wood fiber roof decking combines strength and
insulation advantages that make possible quality
construction with economy. This type of decking is
weather resistant and protected against termites and rot.
The ability of the decking to support specific loads
depends on the support spacing, plank thickness, and
span arrangement. Although two-span continuous
layout offers structural efficiency, use of random-length
Figure 3-6.-Wood fiber roof decking at gable ends.
It is ideally suited for built-up roofing, as well as for
asphalt and wood shingles on all types of buildings.
Wood fiber decking is available in four thicknesses:
2 3/8 inches, 1 7/8 inches, 1 3/8 inches, and 15/16 inch.
The standard panels are 2 inches by 8 feet with
tongue-and-groove edges and square ends. The surfaces
are coated on one or both sides at the factory in a variety
of colors.
Figure 3-7.-Sheathing details at chimney and valley openings.
INSTALLATION.—Wood fiber roof decking is
laid with the tongue-and-groove joint at right angles to
the support members. The decking is started at the cave
line with the groove edge opposite the applicator. Staple
wax paper in position over the rafter before installing
the roof deck. The wax paper protects the exposed
interior finish of the decking if the beams are to be
stained. Caulk the end joints with a nonstaining caulking
compound. Butt the adjacent piece up against the
caulked joint. Drive the tongue-and-groove edges of
each unit firmly together with a wood block cut to fit the
grooved edge of the decking. End joints must be made
over a support member.
Roof decking that extends beyond gable-end walls
for the overhang should span not less than three rafter
spaces. This is to ensure anchorage to the railers and to
prevent sagging (see figure 3-6). When the projection is
greater than 16 to 20 inches, special ladder framing is
used to support the sheathing.
Table 3-2.-Determining Roof Area from a Plan
NAILING.— Although the wood fiber roof panels
have tongue-and-groove edges, they are nailed through
the face into the wood, rafters, or trusses. Face-nail
6 inches OC with 6d nails for 15/16-inch, 8d for
1 3/8-inch, 10d for 1 7/8-inch, and 16d for 2 3/8-inch
If you aren’t going to apply the finish rooting
material immediately after the roof is sheeted, cover the
deck with building felt paper. The paper will protect the
sheathing in case of rain. Wet panels tend to separate.
Table 3-3.-Lumber Sheathing Specifications and Estimating Factor
Plywood extension beyond the end wall is usually
governed by the rafter spacing to minimize waste. Thus,
a 16-inch rake (gable) projection is commonly used
when rafters are spaced 16 inches OC. Butt joints of the
plywood sheets should be alternated so they do not occur
on the same rafter.
To figure the roof area without actually getting on
the roof and measuring, find the dimensions of the roof
on the plans. Multiply the length times the width of the
roof, including the overhang. Then multiply by the
factor shown opposite the rise of the roof in table 3-2.
The result will be the roof area.
For example, assume a building is 70 feet long and
30 feet wide (including the overhang), and the roof has
a rise of 5 1/2 inches: 70 feet x 30 feet = 2,100 square
feet. For arise of 5 1/2 inches, the factor on the chart is
1.100:2,100 square feet x 1.100=2,310 square feet. So,
the total area to be covered is 2,310 square feet. Use this
total area for figuring roofing needs, such as sheathing,
felt underpayment, or shingles.
Where chimney openings occur in the roof
structure, the roof sheathing should have a 3/4-inch
clearance on all sides from the finished masonry. Figure
3-7 shows sheathing details at the valley and chimney
opening. The detail at the top shows the clearances
between masonry and wood-framing members.
Framing members should have a 2-inch clearance for
fire protection. The sheathing should be securely nailed
to the rafters and to the headers around the opening.
Wood or plywood sheathing at the valleys and hips
should be installed to provide a tight joint and should be
securely nailed to hip and valley rafters. This provides
a smooth solid base for metal flashing.
Lumber Sheathing
To decide how much lumber will be needed, first
calculate the total area to be covered. Determine the size
boards to be used, then refer to table 3-3. Multiply the
total area to be covered by the factor from the chart. For
example, if 1- by 8-inch tongue-and-groove sheathing
Table 3-4.-Plank Decking Estimating Factor
traditional designs have considerable y more. Much of the
exterior trim, in the form of finish lumber and moldings,
is cut and fitted on the job. Other materials or
assemblies, such as shutters, louvers, railings, and posts,
are shop fabricated and arrive on the job ready to be
fastened in place.
The properties desired in materials used for exterior
trim are good painting and weathering characteristics,
easy working qualities, and maximum freedom from
warp. Decay resistance is desirable where materials may
absorb moisture. Heartwood from cedar, cypress, and
redwood has high decay resistance. Less durable species
can be treated to make them decay resistant. Many
manufacturers pre-dip materials, such as siding,
window sash, door and window frames, and trim, with
a water-repellent preservative. On-the-job dipping of
end joints or miters cut at the building site is
recommended when resistance to water entry and
increased protection are desired.
Rust-resistant trim fastenings, whether nails or
screws, are preferred wherever they may be in contact
with weather. These include galvanized, stainless steel,
or aluminum fastenings. When a natural finish is used,
nails should be stainless steel or aluminum to prevent
staining and discoloration. Cement-coated nails are not
Siding and trim are normally fastened in place with
a standard siding nail, which has a small flathead.
However, finish or casing nails might also be used for
some purposes. Most of the trim along the shingle line,
such as at gable ends and cornices, is installed before
the roof shingles are applied.
The roof overhangs (eaves) are the portions of the
roof that project past the sidewalls of the building. The
cornice is the area beneath the overhangs. The upward
slopes of the gable ends are called rakes. Several basic
designs are used for finishing off the roof overhangs and
cornices. Most of these designs come under the category
of open cornice or closed cornice. They not only add to
the attractiveness of a building but also help protect the
sidewalls of the building from rain and snow. Wide
overhangs also shade windows from the hot summer
Cornice work includes the installation of the
lookout ledger, lookouts, plancier (soffit), ventilation
screens, fascia, frieze, and the moldings at and below
the eaves, and along the sloping sides of the gable end
(rake). The ornamental parts of a cornice are called
cornice trim and consist mainly of molding; the molding
running up the side of the rakes of a gable roof is called
gable cornice trim. Besides the main roof, the additions
and dormers may have cornices and cornice trim.
boards are to be used, multiply the total roof area by
1.16. To determine the total number of board feet
needed, add 5 percent for trim and waste.
Plywood Sheathing
To determine how much plywood will be needed,
find the total roof area to be covered and divide by 32
(the number of square feet in one 4-by 8-foot sheet of
plywood). This gives you the number of sheets required
to cover the area. Be sure to add 5 percent for a trim and
waste allowance.
Decking or Planking
To estimate plank decking, first determine the area
to be covered, then refer to the chart in table 3-4. In the
left column, find the size planking to be applied. For
example, if 2- by 6-inch material is selected, the factor
is 2.40. Multiply the area to be covered by this factor
and add a 5 percent trim and waste allowance.
Wood Fiber Roof Decking
To estimate the amount of weed fiber decking
required, first find the total roof area to be covered. For
every 100 square feet of area, you will need 6.25 panels,
2 by 8 feet in size. So, divide the roof area by 100 and
multiply by 6.25. Using our previous example with a
roof area of 2,310 square feet, you will need 145 panels.
this section, you should be able to identify the
types of cornices and material used in their
Exterior trim includes door and window trim,
cornice trim, facia boards and soffits, and rake or
gable-end trim. Contemporary designs with simple
cornices and moldings contain little of this material;
Figure 3-8.-Simple cornice.
Figure 3-10.-Closed cornices: A. Flat boxed cornice; B. Sloped
boxed cornice.
A roof with a rafter overhang may have an open
cornice or a closed (also called a box) cornice. In
open-cornice construction (fig. 3-9), the undersides of
the rafters and roof sheathing are exposed. A nailing
header (fascia backer) is nailed to the tail ends of the
rafters to provide a straight and solid nailing base for the
fascia board. Most spaces between the rafters are
blocked off. Some spaces are left open (and screened)
to allow attic ventilation. Usually, a frieze board is nailed
to the wall below the rafters. Sometimes the frieze board
is notched between the rafters and molding is nailed over
it. Molding trim in this position is called bed molding.
In closed-cornice construction, the bottom of the roof
overhang is closed off. The two most common types of
closed cornices are the flat boxed cornice and the sloped
boxed cornice (shown in figure 3-10, views A and B,
Figure 3-9.-Open cornice.
The type of cornice required for a particular
structure is indicated on the wall sections of the
drawings, and there are usually cornice detail drawings
as well. A roof with no rafter overhang or cave usually
has the simple cornice shown in figure 3-8. This cornice
consists of a single strip or board called a frieze. It is
beveled on the upper edge to fit under the overhang or
cave and rabbeted on the lower edge to overlap the upper
edge of the top course of siding. If trim is used, it usually
consists of molding placed as shown in figure 3-8.
Molding trim in this position is called crown molding.
Figure 3-11.-Cornice construction: A. Finish rake for boxed cornice; B. Rake soffit of a sloped box cornice.
end butted against a previously placed panel. First, nail
the panel to the main supports and then along the edges.
Drive nails carefully so the underside of the head is just
flush with the panel surface. Remember, this is finish
work; no hammer head marks please. Always read and
follow manufacturer’s directions and recommended
installation procedures. Cornice trim and soffit systems
are also available in aluminum and come in a variety of
prefinished colors and designs.
The flat boxed cornice requires framing pieces
called lookouts. These are toenailed to the wall or to a
lookout ledger and face-nailed to the ends of the rafters.
The lookouts provide a nailing base for the soffit, which
is the material fastened to the underside of the cornice.
A typical flat boxed cornice is shown in figure 3-10,
view A. For a sloped boxed cornice, the soffit material
is nailed directly to the underside of the rafters (fig. 3-10,
view B). This design is often used on buildings with
wide overhangs.
Soffit systems made of prefinished metal panels and
attachment strips are common. They consist of three
basic components wall hanger strips (also called frieze
strips); soffit panels (solid, vented, or combination); and
fascia covers. Figure 3-12 shows the typical installation
configuration of the components. Soffit panels include
a vented area and are available in a variety of lengths.
The basic rake trim pieces are the frieze board, trim
molding, and the fascia and soffit material. Figure 3-11,
view A, shows the finish rake for a flat boxed cornice.
It requires a cornice return where the cave and rake
soffits join. View B shows the rake of a sloped boxed
cornice. Always use rust-resistant nails for exterior
finish work. hey may be aluminum, galvanized, or
cadmium-plated steel.
Because cornice construction is time-consuming,
various prefabricated systems are available that provide
a neat, trim appearance. Cornice soffit panel materials
include plywood, hardboard, fiberboard, and metal.
Many of these are factory-primed and available in a
variety of standard widths (12 to 48 inches) and in
lengths up to 12 feet. They also maybe equipped with
factory-installed screen vents.
When installing large sections of wood fiber panels,
you should fit each panel with clearance for expansion.
Nail 4d rust-resistant nails 6 inches apart along the edges
and intermediate supports (lookouts). Strut nailing at the
Figure 3-12.-Basic components of prefinished metal soffit
To install a metal panel system, first snap a chalk
line on the sidewall level with the bottom edge of the
fascia board. Use this line as a guide for nailing the wall
hanger strip in place. Insert the panels, one at a time, into
the wall strip. Nail the outer end to the bottom edge of
the fascia board.
After all soffit panels are in place, cut the fascia
cover to length and install it. The bottom edge of the
cover is hooked over the end of the soffit panels. It is
then nailed in place through prepunched slots located
along the top edge. Remember to use nails compatible
with the type of material being used to avoid electrolysis
between dissimilar metals. Again, always study and
follow the manufacturer’s directions when making an
installation of this type.
this section, you should be able to define
roofing terms and identify roofing materials.
The roof covering, or roofing, is a part of the
exterior finish. It should provide long-lived waterproof
protection for the building and its contents from rain,
snow, wind, and, to some extent, heat and cold.
Before we begin our discussion of roof coverings,
let’s first look at some of the mast common terms used
in roof construction.
Figure 3-13.-Roofing terminology: A. Surfaces; B. Slope and
Correct use of roofing terms is not only the mark of
a good worker, but also a necessity for good construction. This section covers some of the more common
roofing terms you need to know.
material over the roof surface. Shingles providing single
coverage are suitable for re-roofing over existing roofs.
Shingles providing double and triple coverage are used
for new construction. Multiple coverage increases
weather resistance and provides a longer service life.
Roofing is estimated and sold by the square. A
square of roofing is the amount required to cover 100
square feet of the roof surface.
Shingle Surfaces
The various surfaces of a shingle are shown in view
A of figure 3-13. “Shingle width” refers to the total
measurement across the top of either a strip type or
individual type of shingle. The area that one shingle
overlaps a shingle in the course (row) below it is referred
to as “top lap.” “Side lap” is the area that one shingle
Coverage is the amount of weather protection
provided by the overlapping of shingles. Depending on
the kind of shingle and method of application, shingles
may furnish one (single coverage), two (double
coverage), or three (triple coverage) thicknesses of
galvanized steel, aluminum, copper, and tin, are
sometimes used. For flat or low-pitched roofs,
composition or built-up roofing with a gravel topping or
cap sheet are frequent combinations. Built-up roofing
consists of a number of layers of asphalt-saturated felt
mopped down with hot asphalt or tar. Metal roofs are
sometimes used on flat decks of dormers, porches, or
overlaps a shingle next to it in the same course. The area
that one shingle overlaps a shingle two courses below it
is known as head lap. Head lap is measured from the
bottom edge of an overlapping shingle to the nearest top
edge of an overlapped shingle. “Exposure” is the area
that is exposed (not overlapped) in a shingle. For the best
protection against leakage, shingles (or shakes) should
be applied only on roofs with a unit rise of 4 inches or
more. A lesser slope creates slower water runoff, which
increases the possibility of leakage as a result of
windblown rain or snow being driven underneath the
butt ends of the shingles.
The choice of materials and the method of
application are influenced by cost, roof slope, expected
service life of the roofing, wind resistance, fire
resistance, and local climate. Because of the large
amount of exposed surface of pitched roofs, appearance
is also important.
“Slope” and “pitch” are often incorrectly used
synonymously when referring to the incline of a sloped
roof. View B of figure 3-13 shows some common roof
slopes with their corresponding roof pitches.
There are basically four types of underlayments you
will be working with as a Builder: asphalt felt, organic,
glass fiber, and tarred.
“Slope” refers to the incline of a roof as a ratio of
vertical rise to horizontal run. It is expressed sometimes
as a fraction but typically as X-in-12; for example, a
4-in-12 slope for a roof that rises at the rate of 4 inches
for each foot (12 inches) of run. The triangular symbol
above the roof in figure 3-13, view B, conveys this
Once the roof sheathing is in place, it is covered with
an asphalt felt underpayment commonly called roofing
felt. Roofing felt is asphalt-saturated and serves three
basic purposes. First, it keeps the roof sheathing dry
until the shingles can be applied. Second, after the
shingles have been laid, it acts as a secondary barrier
against wind-driven rain and snow. Finally, it also
protects the shingles from any resinous materials, which
could be released from the sheathing.
“Pitch” is the incline of a roof as a ratio of the
vertical rise to twice the horizontal run. It is expressed
as a fraction. For example, if the rise of a roof is 4 feet
and the run 12 feet, the roof is designated as having a
pitch of 1/6 (4/24= 1/6).
Roofing felt is designated by the weight per square.
As we mentioned earlier, a square is equal to 100 square
feet and is the common unit to describe the amount of
roofing material. Roofing felt is commonly available in
rolls of 15 and 30 pounds per square. The rolls are
usually 36 inches wide. A roll of 15-pound felt is 144
feet long, whereas a roll of 30-pound felt is 72 feet long.
After you allow for a 2-inch top lap, a roll of 15-pound
felt will cover 4 squares; a roll of 30-pound felt will
cover 2 squares.
In completing roofing projects, you will be working
with a number of different materials. In the following
section, we will discuss the most common types of
underlayments, flashing, roofing cements, and exterior
materials you will encounter. We will also talk about
built-up roofing.
Underpayment should be a material with low vapor
resistance, such as asphalt-saturated felt. Do not use
materials, such as coated felts or laminated waterproof
papers, which act as a vapor barrier. These allow
moisture or frost to accumulate between the
underlayment and the roof sheathing. Underlayment
requirements for different kinds of shingles and various
roof slopes are shown in table 3-5.
Materials used for pitched roofs include shingles of
asphalt, fiberglass, and wood. Shingles add color,
texture, and pattern to the roof surface. To shed water,
all shingles are applied to roof surfaces in some
overlapping fashion. They are suitable for any roof with
enough slope to ensure good drainage. Tile and date are
also popular. Sheet materials, such as roll roofing,
Apply the underpayment as soon as the roof
sheathing has been completed. For single underpayment,
start at the cave line with the 15-pound felt. Roll across
Table 3-5.-Underlayment Recommendations for Shingle Roofs
Figure 3-15.-Protection from ice dams A. Refreezing snow
and ice; B. Cornice ventilation.
enough to extend from the roof edge to between 12 and
24 inches inside the wall line. The roll roofing should
be installed over the underpayment and metal drip edge.
This will lessen the chance of melting snow to back up
under the shingles and fascia board of closed cornices.
Damage to interior ceilings and walls results from this
water seepage. Protection from ice dams is provided by
cave flashing. Cornice ventilation by means of soffit
vents and sufficient insulation will minimize the melting
(fig. 3-15, view B).
Figure 3-14.-Roofing underlayment: A. Single coverage;
B. Double coverage.
the roof with atop lap of at least 2 inches at all horizontal
points and a 4-inch side lap at all end joints (fig. 3-14,
view A). Lap the underlayment over all hips and ridges
6 inches on each side. A double underpayment can be
started with two layers at the cave line, flush with the
fascia board or molding. The second and remaining
strips have 19-inch head laps with 17-inch exposures
(fig. 3-14, view B). Cover the entire roof in this manner.
Make sure that all surfaces have double coverage. Use
only enough fasteners to hold the underpayment in place
until the shingles are applied. Do not apply shingles over
wet underpayment.
ASPHALT FELT.— Roofing felts are used as
underpayment for shingles, for sheathing paper, and for
reinforcements in the construction of built-up roofs.
They are made from a combination of shredded
wood fibers, mineral fibers, or glass fibers saturated
with asphalt or coal-tar pitch. Sheets are usually
36 inches wide and available in various weights from 10
to 50 pounds. These weights refer to weight per square
(100 feet).
In areas where moderate-to-severe snowfall is
common and ice dams occur, melting snow refreezes at
the cave line (fig. 3-15, view A). It is a good practice to
apply one course of 55-pound smooth-surface roll
roofing as a flashing at the eaves. It should be wide
ORGANIC FELTS.— Asphalt-saturated felts
composed of a combination of felted papers and organic
shredded wood fibers are considered felts. They are
among the least expensive of roofing felts and are
widely used not only as roofing, but also as water and
vapor retarders. Fifteen-pound felt is used under wood
siding and exterior plaster to protect sheathing or wood
studs. It is generally used in roofing for layers or plies
in gravel-surfaced assemblies and is available
perforated. Perforated felts used in built-up roofs allow
entrapped moisture to escape during application.
Thirty-pound felt requires fewer layers in a built-up
roof. It is usually used as underlayment for heavier cap
sheets or tile on steeper roofs.
GLASS-FIBER FELTS.— Sheets of glass fiber,
when coated with asphalt, retain a high degree of
porosity, assuring a maximum escape of entrapped
moisture or vapor during application and maximum
bond between felts. Melted asphalt is applied so that the
finished built-up roof becomes a monolithic slab
reinforced with properly placed layers of glass fibers.
The glass fibers, which are inorganic and do not curl,
help create a solid mass of reinforced waterproof
rooting material.
TARRED FELTS.— Coal-tar pitch saturated
organic felts are available for use with bitumens of the
same composition. Since coal-tar and asphalt are not
compatible, the components in any construction must be
limited to one bitumen or the other unless approved by
the felt manufacturer.
The roof edges along the eaves and rake should have
a metal drip edge, or flashing. Flashing is specially
constructed pieces of sheet metal or other materials used
to protect the building from water seepage. Flashing
must be made watertight and be water shedding.
Flashing materials used on roofs may be
asphalt-saturated felt, metal, or plastic. Felt flashing is
generally used at the ridges, hips, and valleys. However,
metal flashing, made of aluminum, galvanized steel, or
copper, is considered superior to felt. Metal used for
flashing must be corrosion resistant. It should be
galvanized steel (at least 26 gauge), 0.019-inch-thick
aluminum, or 16-ounce copper.
Figure 3-16.-Drip edges A. Basic shapes B. At the eave; C. At
the rake.
construction. At the eaves, the underpayment should be
laid over the drip edge (view B). At the rake (view C),
place the underpayment under the drip edge. Galvanized
nails, spaced 8 to 10 inches apart, are recommended for
fastening the drip edge to the sheathing.
The shape and construction of different types of
roofs can create different types of water leakage
problems. Water leakage can be prevented by placing
flashing materials in and around the vulnerable areas of
the roof. These areas include the point of intersection
between roof and soil stack or ventilator, the valley of a
roof, around chimneys, and at the point where a wall
intersects a roof.
Flashing is available in various shapes (fig. 3-16,
view A), formed from 26-gauge galvanized steel. It
should extend back approximately 3 inches from the
roof edge and bend downward over the edge. This
causes the water to drip free of underlying cornice
Figure 3-17.-Flashing around a roof projection.
As you approach a soil stack, apply the roofing up
to the stack and cut it to fit (fig. 3-17). You then install
a corrosion-resistant metal sleeve, which slips over the
stack and has an adjustable flange to fit the slope of the
roof. Continue shingling over the flange. Cut the
shingles to fit around the stack and press them firmly
into the cement.
The open or closed method can be used to construct
valley flashing. A valley underpayment strip of 15-pound
asphalt- saturated felt, 36 inches wide, is applied first.
The strip is centered in the valley and secured with
enough nails to hold it in place. The horizontal courses
of underlayment are cut to overlap this valley strip a
minimum of 6 inches.
Open valleys can be flashed with metal or with
90-pound mineral-surfaced asphalt roll roofing. The
color can match or contrast with the roof shingles. An
18-inch-wide strip of mineral-surfaced roll rooting is
placed over the valley underpayment. It is centered in the
valley with the surfaced side down and the lower edge
cut to conform to and be flush with the cave flashing.
When it is necessary to splice the material, the ends of
the upper segments are laid to overlap the lower
segments 12 inches and are secured with asphalt plastic
cement. This method is shown in figure 3-18. Only
enough nails are used 1 inch in from each edge to hold
the strip smoothly in place.
Another 36-inch-wide strip is placed over the first
strip. It is centered in the valley with the surfaced side
up and secured with nails. It is lapped the same way as
the underlying 18-inch strip.
Before shingles are applied, a chalk line is snapped
on each side of the valley. These lines should start 6
inches apart at the ridge and spread wider apart (at the
rate of 1/8 inch per foot) to the eave (fig. 3-18). The
Figure 3-18.-Open valley flashing using roll roofing.
chalk lines serve as a guide in trimming the shingle units
to fit the valley and ensure a clean, sharp edge. The upper
corner of each end shingle is clipped to direct water into
the valley and prevent water penetration between
courses. Each shingle is cemented to the valley lining
with asphalt cement to ensure a tight seal. No exposed
nails should appear along the valley flashing.
Closed (woven) valleys can be used only with strip
shingles. This method has the advantage of doubling the
coverage of the shingles throughout the length of the
valley. This increases the weather resistance at this
vulnerable point. A valley lining made from a
36-inch-wide strip of 55-pound (or heavier) roll roofing
is placed over the valley underpayment and centered in
the valley (fig. 3-19).
Valley shingles are laid over the lining by either of
two methods:
Figure 3-19.-Closed valley flashing.
Figure 3-21.-Step flashing.
The shingles are pressed tightly into the valley and
nailed in the usual manner. No nail should be located
closer than 6 inches to the valley center line, and two
nails should be used at the end of each terminal strip.
As you approach a chimney, apply the shingles over
the felt up to the chimney face. If 90-pound roll roofing
is to be used for flashing, cut wood cant strips and install
them above and at the sides of the chimney (fig. 3-20).
The roll roofing flashing should be cut to run 10 inches
up the chimney. Working from the bottom up, fit metal
counterflashing over the base flashing and insert it
1 1/2 inches into the mortar joints. Refill the joints with
mortar or roofing cement. The counterflashing can also
be installed when the chimney masonry work is done,
Where the roof intersects a vertical wall, it is best to
install metal flashing shingles. They should be 10 inches
long and 2 inches wider than the exposed face of the
regular shingles. The 10-inch length is bent so that it will
extend 5 inches over the roof and 5 inches up the wall
(see figure 3-21). Apply metal flashing with each
Figure 3-20.-Flashing around a chimney.
They can be applied on both roof surfaces at the
same time with each course, in turn, woven over
the valley.
Each surface can be covered to the point
approximately 36 inches from the center of the
valley and the valley shingles woven in place
In either case, the first course at the valley is laid
along the eaves of one surface over the valley lining and
extended along the adjoining roof surface for a distance
of at least 12 inches. The first course of the adjoining
roof surface is then carried over the valley on top of the
previously applied shingle. Succeeding courses are then
laid alternately, weaving the valley shingles over each
course. This waterproofs the joint between a sloping
roof and vertical wall. This is generally called step
As each course of shingles is laid, a metal flashing
shingle is installed and nailed at the top edge as shown.
Do not nail flashing to the wall; settling of the roof frame
could damage the seal.
Wall siding is installed after the roof is completed.
It also serves as a cap flashing. Position the siding just
above the roof surface. Allow enough clearance to paint
the lower edges.
Figure 3-22.-A typical 12- by 36-inch shingle.
Roof Cements
Roofing cements are used for installing cave
flashing, for flashing assemblies, for cementing tabs of
asphalt shingles and laps in sheet material, and for
repairing roofs. There are several types of cement,
including plastic asphalt cements, lap cements,
quick-setting asphalt adhesives, roof coatings, and
primers. The type and quality of materials and methods
of application on a shingle roof should follow the
recommendation of the manufacturer of the shingle
Figure 3-23.-Special shingle application.
Basically, exterior roof treatment consists of
applying various products, including shingles, roll
roofing, tiles, slate, and bituminous coverings.
Treatment also includes specific construction
considerations for ridges, hips, and valleys.
combination of glass fiber mats with recently developed
resins has significantly lowered the price of composition
Strip.— One of the most common shapes of asphalt
or fiberglass shingles is a 12- by 36-inch strip (fig. 3-22)
with the exposed surface cut or scored to resemble three
9-by 12-2- inch shingles. These are called strip shingles.
They are usually laid with 5 inches exposed to the
weather. A lap of 2 to 3 inches is usually provided over
the upper edge of the shingle in the course directly
below. This is called the head lap.
SHINGLES.— The two most common shingle
types are asphalt and fiberglass, both of which come in
various strip shapes.
Asphalt.— Asphalt (composition) shingles are
available in several patterns. They come in strip form or
as individual shingles. The shingles are manufactured
on a base of organic felt (cellulose) or an inorganic glass
mat. The felt or mat is covered with a mineral-stabilized
coating of asphalt on the top and bottom. The top side
is coated with mineral granules of specified color. The
bottom side is covered with sand, talc, or mica.
The thickness of asphalt shingles may be uniform
throughout, or, as with laminated shingles, slotted at the
butts to give the illusion of individual units. Strip
shingles are produced with either straight-tab or
random-tab design to give the illusion of individual units
or to simulate the appearance of wood shakes. Most strip
shingles have factory-applied adhesive spaced at
intervals along the concealed portion of the strip. These
strips of adhesive are activated by the warmth of the sun
and hold the shingles firm through wind, rain, and snow.
Fiberglass.— Improved technologies have made
the fiberglass mat competitive with organic felt. The
weight and thickness of a fiberglass mat is usually less
than that of organic felt. A glass fiber mat maybe 0.030
inch thick versus 0.055 inch thick for felt. The
popularity of fiberglass-based shingles is their low cost.
The mat does not have to be saturated in asphalt. ASTM
standards specify 3 pounds per 100 feet. The
Strip shingles are usually laid over a single
thickness of asphalt-saturated felt if the slope of the roof
Figure 3-24.-Laying out a shingle roof.
is 4:12 or greater. When special application methods are
used, organic- or inorganic-base-saturated or coatedstrip shingles can be applied to decks having a slope of
4:12, but not less than 2:12. Figure 3-23 shows the
application of shingles over a double layer of
underpayment. Double underpayment is recommended
under square-tab strip shingles for slopes less than 4:12.
When roofing materials are delivered to the building
site, they should be handled with care and protected
from damage. Try to avoid handling asphalt shingles in
extreme heat or cold. They are available in
one-third-square bundles, 27 strip shingles per bundle.
Bundles should be stored flat so the strips will not curl
after the bundles are open. To get the best performance
from any roofing material, always study the
manufacturer’s directions and install as directed.
to achieve the proper horizontal and vertical placement
of the shingles (fig. 3-24).
The first chalk line from the cave should allow for
the starter strip and/or the first course of shingles to
overhang the drip edge 1/4 to 3/8 inch.
When laying shingles from the center of the roof
toward the ends, snap a number of chalk lines between
the eaves and ridge. These lines will serve as reference
marks for starting each course. Space them according to
the shingle type and laying pattern.
Chalk lines, parallel to the eaves and ridge, will help
maintain straight horizontal lines along the butt edge of
the shingle. Usually, only about every fifth course needs
to be checked if the shingles are skillfully applied.
Inexperienced workers may need to set up chalk lines
for every second course.
The purpose of a starter strip is to back up the first
course of shingles and fill in the space between the tabs.
Use a strip of mineral-surfaced roofing 9 inches or wider
of a weight and color to match the shingles. Apply the
strip so it overhangs the drip edge 1/4 to 3/8 inch above
the edge. Space the nails so they will not be exposed at
the cutouts between the tabs of the first course of
shingles. Sometimes an inverted (tabs to ridge) row of
shingles is used instead of the starter strip. When you
On small roofs (up to 30 feet long), strip shingles
can be laid starting at either end. When the roof surface
is over 30 feet long, it is usually best to start at the center
and work both ways. Start from a chalk line
perpendicular to the eaves and ridge.
Asphalt shingles will vary slightly in length (plus or
minus 1/4 inch in a 36-inch strip). There may also be
some variations in width. Thus, chalk lines are required
galvanized steel nails with barbed shanks. Aluminum
nails are also used. The length should be sufficient to
penetrate the full thickness of the sheathing or 3/4 inch
into the wood.
The number of nails and correct placement are both
vital factors in proper application of rooting material.
For three-tab square-butt shingles, use a minimum of
four nails per strip (fig. 3-25, view C). Specifications
may require six nails per shingle (view C). Align each
shingle carefully and start the nailing from the end next
to the one previously laid. Proceed across the shingle.
This will prevent buckling. Drive nails straight so that
the edge of the head will not cut into the shingle. The
nail head should be driven flush, not sunk into the
surface. If, for some reason, the nail fails to hit solid
sheathing, drive another nail in a slightly different
shingles are available in three standard lengths: 16, 18,
and 24 inches. The 16-inch length is the most popular.
It has five-butt thicknesses per 2 inches of width when
it is green (designated a 5/2). These shingles are packed
in bundles. Four bundles will cover 100 square feet of
wall or roof with 5-inch exposure. The 18- or
24-inch-long shingles have thicker butts-five in 2 1/4
inches for the 18-inch shingles and four in 2 inches for
24-inch shingles. The recommended exposures for the
standard wood-shingle size are shown in table 3-6.
Figure 3-25.-Nails suitable for installing strip shingles,
recommended nail lengths, and nail placement.
are laying self-sealing strip shingles in windy areas, the
starter strip is often formed by cutting off the tabs of the
shingles being used. These units are then nailed in place,
right side up, and provide adhesive under the tabs of the
first course.
Figure 3-26 shows the proper method of applying a
wood-shingle roof. Underpayment or roofing felt is not
required for wood shingles except for protection in ice
jam areas. Although spaced or solid sheathing is
optional, spaced roof sheathing under wood shingles is
most common. Observe the following steps when
applying wood shingles:
Nails used to apply asphalt roofing must have a
large head (3/8- to 7/16-inch diameter) and a sharp point.
Figure 3-25 shows standard nail designs (view A) and
recommended lengths (view B) for nominal 1-inch
sheathing. Most manufacturers recommend 12-gauge
1. Extend the shingles 1 1/2 inches beyond the cave
line and 3/4 inch beyond the rake (gable) edge.
Table 3-6.-Recommended Exposure for Wood Shingles
and 13 inches for 32-inch shakes. Shakes are not smooth
on both faces, and because wind-driven rain or snow
might enter, it is essential to use an underpayment
between each course. A layer of felt should be used
between each course with the bottom edge positioned
above the butt edge of the shakes a distance equal to
double the weather exposure. A 36-inch-wide strip of
the asphalt felt is used at the cave line. Solid sheathing
should be used when wood shakes are used for roofs in
areas where wind-driven snow is common.
ROLL ROOFING.— Roll roofing is made of an
organic or inorganic felt saturated with an asphalt
coating and has a viscous bituminous coating. Finely
ground talc or mica can be applied to both sides of the
saturated felt to produce a smooth roofing. Mineral
granules in a variety of colors are rolled into the upper
surface while the final coating is still soft. These mineral
granules protect the underlying bitumen from the
deteriorating effects of sun rays. The mineral aggregates
are nonflammable and increase the fire resistance and
improve the appearance of the underlying bitumen.
Mineral-surfaced roll roofing comes in weights of 75 to
90 pounds per square. Roll roofing may have one
surface completely covered with granules or have a
2-inch plain-surface salvage along one side to allow for
Figure 3-26.-Installation of wood shingles.
2. Use two rust-resistant nails in each shingle.
Space them 3/4 inch from the edge and 1 1/2
inches above the butt line of the next course.
3. Double the first course of shingles. In all
courses, allow 1/8- to 1/4-inch space between
each shingle for expansion when they are wet.
Offset the joints between the shingles at least 1
1/2 inches from the joints in the course below.
In addition, space the joints in succeeding
courses so that they do not directly line up with
joints in the second course below.
Roll roofing can be installed by either exposed or
concealed nailing. Exposed nailing is the cheapest but
doesn’t last as long. This method uses a 2-inch lap at the
side and ends. It is cemented with special cement and
nailed with large-headed nails. In concealed-nailing
installations, the roll roofing is nailed along the top of
the strip and cemented with lap cement on the bottom
edge. Vertical joints in the roofing are cemented into
place after the upper edge is nailed. This method is used
when maximum service life is required.
4. Where valleys are present, shingle away from
them. Select and precut wide valley shingles.
5. Use metal edging along the gable end to aid in
guiding the water away from the sidewalls.
6. Use care when nailing wood shingles. Drive the
nails just flush with the surface. The wood in
shingles is soft and can be easily crushed and
damaged under the nail heads.
Wood shakes are usually available in several types,
but the split-and-resawed type is the most popular. The
sawed face is used as the back face and is laid flat on the
roof. The butt thickness of each shake ranges between
3/4 inch and 1 1/2 inches. They are usually packed in
bundles of 20 square feet with five bundles to the square.
Double-coverage roll roofing is produced with
slightly more than half its surface covered with granules.
This roofing is also known as 19-inch salvage edge. It
is applied by nailing and cementing with special
adhesives or hot asphalt. Each sheet is lapped 19 inches,
blind-nailed in the lapped salvage portion, and then
cemented to the sheet below. End laps are cemented into
Wood shakes are applied in much the same way as
wood shingles. Because shakes are much thicker (longer
shakes have the thicker butts), use long galvanized nails.
To create a rustic appearance, lay the butts unevenly.
Because shakes are longer than shingles, they have
greater exposure. Exposure distance is usually 7 1/2
inches for 18-inch shakes, 10 inches for 24-inch shakes,
TILES.— Roofing tile was originally a thin, solid
unit made by shaping moist clay in molds and drying it
in the sun or in a kiln. Gradually, the term has come to
include a variety of tile-shaped units made of clay,
Portland cement, and other materials. Tile designs have
come down to us relatively unchanged from the Greeks
and Remans. Roofing tiles are durable, attractive, and
Table 3-7.-Weight of Roofing Materials
resistant to fire; however, because of their weight
(table 3-7), they usually require additional structural
framing members and heavier roof decks.
Clay.— The clays used in the manufacture of
roofing tile are similar to those used for brick. Unglazed
tile comes in a variety of shades, from a yellow-orange
to a deep red, and in blends of grays and greens. Highly
glazed tiles are often used on prominent buildings and
for landmark purposes.
Clay roofing tiles are produced as either flat or roll
tile. Flat tile may be English (interlocking shingle) or
French. Roll tiles are produced in Greek or Roman
pan-and-cover, Spanish or Mission style (fig. 3-27).
Roll Tile.— Roll tile is usually installed over two
layers of hot-mopped 15-pound felt. Double-coverage
felts, laid shingle fashion, lapped 19 inches, and mopped
with hot asphalt, may be required as an underpayment.
The individual tiles are nailed to the sheathing through
prepunched holes. Special shapes are available for
starter courses, rakes, hips, and ridges. Some
manufacturers produce tiles in special tile-and-a-half
units for exposed locations, such as gables and hips.
Figure 3-27.-Types of clay roof tiles.
These are designed to restrict lateral movement and
provide weather checks between the tiles. The underside
of the tile usually contains weather checks to halt
wind-blown water. Head locks, in the form of lugs,
overlap wood battens roiled to solid sheathing or strips
of spaced sheathing. Nail holes are prepunched The
most common size of concrete tile is 123/8 by 17 inches.
This provides for maximum coverage with minimum
Mission Tile.— Mission tiles are slightly tapered
half-round units and are set in horizontal courses. The
convex and concave sides are alternated to form pans
and covers. The bottom edges of the covers can be laid
with a random exposure of 6 to 14 inches to weather.
Mission tile can be fastened to the prepared roof deck
with copper nails, copper wire, or specially designed
brass strips. The covers can be set in portland cement
mortar. This gives the roof a rustic appearance, but it
adds approximately 10 pounds per square to the weight
of the finished roof.
Concrete tiles are designed for minimum roof
slopes of 2 1/2:12. For slopes up to 3 1/2:12, roof decks
are solidly sheeted and covered with roofing felt. For
slopes greater than 3 1/2:12, the roof sheathing can be
spaced. Roofing felt is placed between each row to carry
any drainage to the surface of the next lower course of
tile. The lugs at the top of the tiles lock over the
sheathing or stripping. Generally, only every fourth tile
in every fourth row is nailed to the sheathing, except
where roofs are exposed to extreme winds or earthquake
conditions. The weight of the tile holds it in place.
Flat Tile.— Flat tile can be obtained as either flat
shingle or interlocking. Single tiles are butted at the
sides and lapped shingle fashion. They are produced in
various widths from 5 to 8 inches with a textured surface
to resemble wood shingles, with smooth colored
surfaces, or with highly glazed surfaces. Interlocking
shingle tiles have side and top locks, which permit the
use of fewer pieces per square. The back of this type of
tile is ribbed. This reduces the weight without sacrificing
strength. Interlocking flat tile can be used in
combination with lines of Greek pan-and-cover tile as
Lightweight concrete tile is now being produced
using fiberglass reinforcing and a lightweight perlite
aggregate. These tiles come in several colors and have
the appearance of heavy cedar shakes. The weight of
these shingles is similar to that of natural cedar shakes,
so roof reinforcing is usually unnecessary.
Concrete.— The acceptance of concrete tile as a
roofing material has been slow in the United States.
However, European manufacturers have invested
heavily in research and development to produce a
uniformly high-quality product at a reasonable cost.
Concrete tile is now used on more than 80 percent of all
new residences in Great Britain. Modern high-speed
machinery and techniques have revolutionized the
industry in the United States, and American-made
concrete tiles are now finding a wide market,
particularly in the West.
SLATE.— Slate roofing is hand split from natural
rock. It varies in color from black through blue-gray,
gray, purple, red and green. The individual slates may
have one or more darker streaks running across them.
These are usually covered during the laying of the slate.
Most slate rooting is available in sizes from 10 by 6 to
26 by 14 inches. The standard thickness is 3/16 inch, but
thicknesses of 1/4, 3/8, 1/2, and up to 2 inches can be
obtained. Slate may be furnished in a uniform size or in
random widths. The surface may be left with the rough
hand-split texture or ground to a smoother texture.
Concrete roof tile, made of Portland cement, sand,
and water, is incombustible. It is also a poor conductor
of heat. These characteristics make it an ideal roofing
material in forested or brushy areas subject to periodic
threats of fire. In addition, concrete actually gains
strength with age and is unaffected by repeated freezing
and thawing cycles.
The weight of a slate roof ranges from 700 to 1,500
pounds per square, depending upon thickness. The size
of framing members supporting a slate roof must be
checked against the weight of the slate and method of
laying. The type of underpayment used for a slate roof
varies, depending on local codes. The requirement
ranges from one layer of 15-pound asphalt-saturated felt
to 65-pound rolled asphalt roofing for slate over 3/4 inch
Color pigments may be mixed with the basic
ingredients during manufacture. To provide a glazed
surface, cementitious mineral-oxide pigments are
sprayed on the tile immediately after it is extruded. This
glaze becomes an integral part of the tile. The surface of
these tiles may be scored to give the appearance of rustic
wood shakes.
Slate is usually laid like shingles with each course
lapping the second course below at least 3 inches. The
slates can be laid in even rows or at random. Each slate
is predrilled with two nail holes and is held in place with
Most concrete tiles are formed with side laps
consisting of a series of interlocking ribs and grooves.
two large-headed slaters’ nails. These are made of hard
copper wire, cut copper, or cut brass. On hips, ridges,
and in other locations where nailing is not possible, the
slates are held in place with waterproof elastic slaters’
cement colored to match the slate. Exposed nail heads
are covered with the same cement.
BITUMENS.— Hot bituminous compounds
(bitumens) are used with several types of roofing
systems. Both asphalt and coal-tar pitch are bitumens.
Although these two materials are similar in appearance,
they have different characteristics. Asphalt is usually a
product of the distillation of petroleum, whereas coal-tar
pitch is a byproduct of the coking process in the
manufacture of steel.
Some asphalts are naturally occurring or are found
in combination with porous rock. However, most
roofing asphalts are manufactured from petroleum
crudes from which the lighter fractions have been
removed. Roofing asphalts are available in a number of
different grades for different roof slopes, climatic
conditions, or installation methods.
Roofing asphalts are graded on the basis of their
softening points, which range from a low of 135°F
(57.2°C) to a high of 225°F (107.2°C). The softening
point is not the point at which the asphalt begins to flow,
but is determined by test procedures established by the
ASTM. Asphalts begin to flow at somewhat lower
temperatures than their softening points, depending on
the slope involved and the weight of the asphalt and
surfacing material.
Generally, the lower the softening point of an
asphalt, the better its self-healing properties and the less
tendency it has to crack. Dead-flat roofs, where water
may stand, or nearly flat roofs, require an asphalt that
has the greatest waterproofing qualities and the
self-healing properties of low-softening asphalts. A
special asphalt known as dead-flat asphalt is used in
such cases. As the slope of the roof increases, the need
for waterproofing is lessened, and an asphalt that will
not flow at expected normal temperatures must be used.
For steeper roofing surfaces, asphalt with a softening
point of 185°F to 205°F (85°C to 96.1°C) is used. This
material is classed as steep asphalt. In hot, dry climates
only the high-temperature asphalts can be used.
Figure 3-28.-Finish at the ridge: A. Boston ridge with strip
shingles; B. Boston ridge with wood shingles; C. Metal
roof surfaces often reach temperatures of 126°F to
147°F (52.2°C to 63.9°C) in the hot desert sun, the
low-softening point of coal-tar pitch makes it unsuitable
as a roof surfacing material.
When used within its limitations on flat and
low-pitched roofs in suitable climates, coal-tar pitch
provides one of the most durable roofing membranes.
Coal-tar pitch is also reputed to have cold-flow, or
self-healing, qualities. This is because the molecular
structure of pitch is such that individual molecules have
a physical attraction for each other, so self-sealing is not
The softening point of coal-tar pitch generally
ranges from 140°F to 155°F (60.0°C to 68.3°C). The
softening point of coal-tar pitch limits its usefulness;
however, it has been used successfully for years in the
eastern and middle western parts of the United States on
dead-level or nearly level roofs. In the southwest, where
Figure 3-29.-Layout pattern for hip and valley shingles.
formed to the roof slope and should be copper,
galvanized iron, or aluminum. Some metal ridges are
formed so that they provide an outlet ventilating area.
However, the design should be such that it prevents rain
or snow from blowing in.
dependent on heat. Coal-tar pitch roofs are entirely
unaffected by water. When covered by mineral
aggregate, standing water may actually protect the
volatile oils.
Laying rooting on a flat surface is a relatively easy
procedure. Correctly applying materials to irregular
surfaces, such as ridges, hips, and valleys, is somewhat
more complex.
Hips and Valleys.— One side of a hip or valley
shingle must be cut at an angle to obtain an edge that
will match the line of the hip or valley rafter. One way
to cut these shingles is to use a pattern. First, select a 3
foot long 1 by 6. Determine the unit length of a common
rafter in the roof (if you do not already know it). Set the
framing square on the piece to get the unit run of the
common rafter on the blade and the unit rise of the
common rafter on the tongue (fig. 3-29). Draw a line
along the tongue; then saw the pattern along this line.
Note: The line cannot be used as a pattern to cut a hip
or valley.
Ridge.— The most common type of ridge and hip
finish for wood and asphalt shingles is the Boston ridge.
Asphalt-shingle squares (one-third of a 12- by 36-inch
strip) are used over the ridge and blind-nailed (fig. 3-28,
view A). Each shingle is lapped 5 to 6 inches to give
double coverage. In areas where driving rains occur, use
metal flashing under the shingle ridge to help prevent
seepage. The use of a ribbon of asphalt roofing cement
under each lap will also help.
Built-up Rooting
A wood-shingle roof should be finished with a
Boston ridge (fig. 3-28, view B). Shingles, 6 inches
wide, are altemately lapped, fitted, and blind-nailed. As
shown, the shingles are nailed in place so that the
exposed trimmed edges are alternately lapped.
Reassembled hip and ridge units for wood-shingle roofs
are available and save both time and money.
A built-up roof, as the name indicates, is built up in
alternate plies of roofing felt and bitumen. The bitumen
forms a seamless, waterproof, flexible membrane that
conforms to the surface of the roof deck and protects all
angles formed by the roof deck and projecting surfaces,
Without the reinforcement of the felts, the bitumens
would crack and alligator and thus lose their volatile oils
under solar radiation.
A metal ridge can also be used on asphalt-shingle or
wood-shingle roofs (fig. 3-28, view C). This ridge is
View B shows a three-ply built-up roof over a nonnailable deck with a gravel or slag surface. View C
shows a four-ply built-up roof over insulation, with a
gravel or slag surface.
The temperatures at which bitumens are applied
are very critical. At high temperatures, asphalt is
seriously damaged and its life considerably shortened.
Heating asphalt to over 500°F (260°C) for a prolonged
period may decrease the weather life by as much as 50
percent. Coal-tar pitch should not be heated above
400°F (204°C). Asphalt should be applied to the roof at
an approximate temperature of 375°F to 425°F
(190.6°C to 218.3°C), and coal-tar pitch should be
applied at 275°F to 375°F (135°C to 190°C).
Bitumens are spread between felts at rates of 25 to
35 pounds per square, depending on the type of ply or
roofing felt. An asphalt primer must be used over
concrete before the hot asphalt is applied. It usually is
unnecessary to apply a primer under coal-tar pitch.
With wood and other types of nailable decks, the ply is
nailed to the deck to seal the joints between the units
and prevent dripping of the bitumens through the
Built-up roofs are classed by the number of plies of
felt that is used in their construction. The roof maybe
three-ply, four-ply, or five-ply, depending on whether
the roofing material can be nailed to the deck whether
insulation is to be applied underneath it, the type of
surfacing desired, the slope of the deck, the climatic
conditions, and the life expectancy of the roofing.
The ply-and-bitumen membrane of a built-up roof must
form a flexible covering that has sufficient strength to
withstand normal structure expansion. Most built-up
roofs have a surfacing over the last felt ply. This
protective surfacing can be applied in several ways.
SURFACING.—Glaze-coat and gravel surfaces are
the most commonly seen bituminous roofs.
Figure 3-30.-Types of built-up roofing.
Glaze Coat.—A coat of asphalt can be flooded over
the top layer of felt. This glaze coat protects the top
layer of felt from the rays of the sun. The glaze coat is
black, but it maybe coated with white or aluminum
surfacing to provide a reflective surface.
applying roofing depends on the type of roof deck.
Some roof decks are nailable and others are not. Figure
3-30 shows examples of wood deck (nailable), concrete
deck (not nailable), and built-up roof over insulation.
Nailable decks include such materials as wood or
fiberboard, poured or precast units of gypsum, and nail
able lightweight concrete. Non-nailable decks of
concrete or steel require different techniques of roofing.
View A of figure 3-30 shows a three-ply built-up roof
over a nailable deck, with a gravel or slag surface.
Gravel.—A flood coat of bitumen (60 pounds of
asphalt or 70 pounds of coal-tar pitch per square) is
applied over the top ply. Then a layer of aggregate,
such as rock gravel, slag, or ceramic granules, is
applied while the flood coat is still hot. The gravel
Figure 3-31.-Laying a five-ply built-up roof.
approximately 400 pounds per square and the slag 325
pounds per square. Other aggregates would be applied
at a rate consistent with their weight and opacity. The
surface aggregate protects the bitumen from the sun and
provides a fire-resistant coating.
DRAINAGE.—When required, positive drainage
should be established before the installation of built-up
roofing. This can be achieved by the use of lightweight
concrete or roofing insulation placed as specified with
slopes toward roof drains, gutters, or scuppers.
CAP SHEETS.—A cap sheet surface is similar to
gravel-surfaced roofings, except that a mineral-surface is
used in place of the flood coat and job-applied gravel.
Cap-sheet roofing consists of heavy roofing felts (75 to
105 pounds per square) of organic or glass fibers.
Mineral-surfaced cap sheets are coated on both sides
with asphalt and surfaced on the exposed side with
mineral granules, mica, or similar materials. The cap
sheets are applied with a 2-inch lap for single-ply
construction or a 19-inch lap if two-ply construction is
desired. The mineral surfacing is omitted on the portion
that is lapped. The cap sheets are laid in hot asphalt
along with the base sheet. Cap sheets are used on slopes
between 1/2: 12 and 6:12 where weather is moderate.
consists of several layers of tar-rag-felt, asphalt-rag-felt,
or asphalt-asbestos-felt set in a hot binder of melted
pitch or asphalt.
Each layer of built-up roofing is called a ply. In a fiveply roof, the first two layers are laid without a binder;
these are called the dry nailers. Before the nailers are
nailed in place, a layer of building paper is tacked down
to the roof sheating.
A built-up roof, like a shingled roof, is started at the
eaves so the strips will overlap in the direction of the
watershed. Figure 3-31 shows how 32-inch building
paper is laid over a wood-sheathing roof to get five-ply
coverage at all points in the roof. There are basically
seven steps to the process.
emulsions, cutback asphalts, or patented products can be
applied over the top ply of a hot-mopped roof or as an
adhesive between plies. If emulsified asphalt is to be
used as art adhesive between plies, special plies (such as
glass fiber) must be used that are sufficiently porous to
allow vapors to escape. Decorative and reflective
coatings with asphalt-emulsion bases have been
developed to protect and decorate roofing.
1. Lay the building paper with a 2-inch overlap.
Spot-nail it down just enough to keep it from
blowing away.
2. Cut a 16-inch strip of saturated felt and lay it
along the eaves. Nail it down with nails placed 1
inch from the back edge and spaced 12 inches OC.
3. Nail a full-width (32-inch) strip over the first
strip, using the same nailing schedule.
4. Nail the next full-width strip with the outer edge
14 inches from the outer edges of the first two
strips to obtain a 2-inch overlap over the edge of
the first strip laid. Continue laying full-width
strips with the same exposure (14 inches) until
the opposite edge of the roof is reached. Finish
off with a half-strip along this edge. This
completes the two-ply dry nailer.
material is tapped off. Pieces must not be thrown into
the melted mass, but placedon the surface, pushed under
slowly, and then released. If the material is not being
steadily tapped off, it may eventually overheat, even
with the burner flame at the lowest possible level. In that
case, the burner should be withdrawn from the kettle and
placed on the ground to be reinserted when the
temperature falls. Prolonged overheating causes
flashing and impairs the quality of the binder.
Asphalt or pitch must not be allowed to accumulate
on the exterior of the kettle because it creates a fire
hazard. If the kettle catches fire, close the lid
immediately, shut off the pressure and burner valves,
and, if possible, remove the burner from the kettle.
Never attempt to extinguish a kettle fire with water. Use
sand, dirt, or a chemical fire extinguisher.
5. Start the three-ply hot with one-third of a strip,
covered by two-thirds of a strip, and then by a
full strip, as shown. To obtain a 2-inch overlap
of the outer edge of the second full strip over the
inner edge of the first strip laid, you must
position the outer edge of the second full strip 8
2/3 inches from the outer edges of the first three
strips. To maintain the same overlap, lay the
outer edge of the third full strip 10 1/3 inches
from the outer edge of the second full strip.
Subsequent strips can be laid with an exposure
of 10 inches. Finish off at the opposite edge of
the roof with a full strip, two-thirds of a strip,
and one-third of a strip to maintain three plies
A hot rooting crew consists of a mopper and as
many felt layers, broomers, nailers, and carriers as the
size of the roof requires. The mopper is in charge of the
roofing crew. It is the mopper’s personal responsibility
to mop on only binder that is at the proper temperature.
Binder that is too hot will burn the felt, and the layer it
makes will be too thin. A layer that is too thin will
eventually crack and the felt may separate from the
binder. Binder that is too cold goes on too thick so more
material is used than is required.
6. Spread a layer of hot asphalt (the flood coat)
over the entire roof.
7. Sprinkle a layer of gravel, crushed stone, or slag
over the entire roof.
The felt layer must get the felt down as soon as
possible after the binder has been placed. If the interval
between mopping and felt laying is too long, the binder
will cool to the point where it will not bond well with
the felt. The felt layer should follow the mopper at an
interval of not more than 3 feet. The broomer should
follow immediately behind the felt layer, brooming out
all air bubbles and embedding the felt solidly in the
Melt the binder and maintain it at the proper
temperature in a pressure fuel kettle. Make sure the
kettle is suitably located. Position it broadside to the
wind, if possible. The kettle must be set up and kept
level. If it is not level, it will heat unevenly, creating a
hazard. The first duty of the kettle operator is to inspect
the kettle, especially to ensure that it is perfectly dry.
Any accumulation of water inside will turn to steam
when the kettle gets hot. This can cause the hot binder
to bubble over, which creates a serious fire hazard.
Detailed procedure for lighting off, operating, servicing,
and maintaining the kettle is given in the manufacturer’s
manual. Never operate the kettle unattended, while the
trailer is in transit, or in a confined area.
Buckets of hot binder should never be filled more
than three-fourths full, and they should never be carried
any faster than a walk. Whenever possible, the mopper
should work downwind from the felt layer and broomer
to reduce the danger of spattering. The mopper must
take every precaution against spattering at all times. The
mopper should lift the mop out of the bucket, not drag
it across the rim. Dragging the mop over the rim may
upset the bucket, and the hot binder may quickly spread
The kettle operator must maintain the binder at a
steady temperature, as indicated by the temperature
gauge on the kettle. Correct temperature is designated
in binder manufacturer’s specifications. For asphalt, it
is about 400°F. The best way to keep an even
temperature is to add material at the same rate as melted
to the feet, or worse still to the knees, of nearby members
of the roofing crew.
Design of Wood Frame Structures for Permanence,
National Forest Products Association, Washington,
D.C., 1988.
Although the following references
were current when this TRAMAN was
published, their continued currency
cannot be assured You therefore need
to ensure that you are studying the
latest revisions.
Manual of Built-up Roof Systems, C. W. Griffin,
McGraw-Hill Book Co., New York, 1982.
Basic Roof Framing, Benjamin Barnow, Tab Books,
Inc., Blue Ridge Summit, Pa., 1986.
Modern Carpentry, Willis H. Wagner, GoodheartWilcox Co., South Holland, Ill., 1983.
Exterior and Interior Trim, John E. Ball, Delmar Pub.,
Albany, N.Y., 1975.
due to changes in moisture content, choose verticalgrain (edge-grain) siding. While this is not as
important for a stained finish, the use of edge-grain
siding for a paint finish will result in longer paint
life. A 3-minute dip in a water-repellent preservative
before siding is installed will result in longer paint
life and resist moisture entry and decay. Some
manufacturers supply siding with this treatment.
Freshly cut ends should be brush-treated on the job.
In this chapter, we’ll continue our discussion of
exterior finishing. In chapter 3, we covered roof
finishing; here, we’ll examine the exterior finishing of
walls, including exterior doors, windows, and glass.
LEARNING OBJECTIVE: Upon completing this
section, you should be able to identify the types of
exterior wall coverings and describe procedures for
installing siding.
Some wood siding patterns are used only horizontally and others only vertically. Some may be used
in either manner if adequate nailing areas are
provided. A description of each of the general types of
horizontal siding follows.
Because siding and other types of exterior wall
covering affect the appearance and the maintenance
of a structure, the material and pattern should be
selected carefully. Wood siding can be obtained in
many different patterns and can be finished
naturally, stained, or painted. Wood shingles,
plywood, wood siding (paneling), fiberboard, and
hardboard are some of the types of material used as
exterior coverings. Masonry, veneers, metal or plastic
siding, and other nonwood materials are additional
choices. Many prefinished sidings are available, and
the coatings and films applied to several types of base
materials may eliminate the need of refinishing for
many years.
PLAIN BEVEL.— Plain bevel siding (fig. 4-1) can
be obtained in sizes from 1/2 by 4 inches to 1/2 by
One of the materials most used for structure
exteriors is wood siding. The essential properties
required for siding are good painting characteristics,
easy working qualities, and freedom from warp. Such
properties are present to a high degree in cedar,
eastern white pine, sugar pine, western white pine,
cypress, and redwood; to a good degree in western
hemlock, spruce, and yellow popular; and to a fair
degree in Douglas fir and yellow pine.
The material used for exterior siding that is to be
painted should be of a high grade and free from
knots, pitch. pockets, and uneven edges. Vertical
grain and mixed grain (both vertical and flat) are
available in some species, such as redwood and
western red cedar. The moisture content at the time
of application should be the same as what it will
attain in service. To minimize seasonal movement
Figure 4-1.-Types of wood siding.
8 inches and also in sizes of 3/4 by 8 inches and 3/4 by
10 inches. “Anzac” siding is 3/4 by 12 inches in size.
Usually, the finished width of bevel siding is about
one-half inch less than the size listed. One side of
beveled siding has a smooth planed surface, whereas the
other has a rough resawn surface. For a stained finish,
the rough or sawn side is exposed because wood stain
works best and lasts longer on rough wood surfaces.
DOLLY VARDEN.— Dolly Varden siding is
similar to true bevel siding except that it has shiplap
edges. The shiplap edges have a constant exposure
distance (fig. 4-1). Because it lays flat against the studs,
it is sometimes used for garages and similar buildings
without sheathing. Diagonal bracing is therefore needed
to stiffen the building and help the structure withstand
strong winds and other twist and strain forces.
DROP SIDING.— Regular drop siding can be
obtained in several patterns, two of which are shown in
figure 4-1. This siding, with matched or shiplap edges,
is available in 1- by 6-inch and 1- by 8-inch sizes. It is
commonly used for low-cost dwellings and for garages,
usually without sheathing. Tests have shown that the
tongue-and-grooved (matched) patterns have greater
resistance to the penetration of wind-driven rain than the
shiplap patterns, when both are treated with a
water-repellent preservative.
Figure 4-2.-Vertica1 board siding.
Treating the edges of drop, matched, and shiplapped
sidings with water-repellent preservative helps prevent
wind-driven rain from penetrating the joints exposed to
the weather. In areas under wide overhangs or in porches
or other protected sections, the treatment is not as
important. Some manufacturers provide siding with this
treatment already applied.
Fiberboard and Hardboard
Fiberboard and hardboard sidings are also available
in various forms. Some have a backing to provide
rigidity and strength, whereas others are used directly
over sheathing. Plywood horizontal lap siding, with a
medium-density overlaid surface, is also available as an
exterior covering material. It is usually 3/8 inch thick
and 12 or 16 inches wide. It is applied in much the same
manner as wood siding, except that a shingle wedge is
used behind each vertical joint.
A method of siding application, popular for some
architectural styles, uses rough-sawn boards and battens
applied vertically. These can be arranged in three ways:
board and batten, batten and board, and board and board
(fig. 4-2).
Sheet Materials
A number of siding or paneling patterns can be used
horizontally or vertically (fig. 4-1). These are
manufactured in nominal 1-inch thicknesses and in
widths from 4 to 12 inches. Both dressed and matched
and shiplapped edges are available. The narrow and
medium-width patterns are usually more satisfactory
under moderate moisture content changes. Wide
patterns are more successful if they are vertical-grained
(to keep shrinkage to a minimum). The correct moisture
content is necessary in tongue-and-groove material to
prevent shrinkage and tongue exposure.
A number of sheet materials are now available for
use as siding. These include plywood in a variety of face
treatments and species, and hardboard. Plywood or
paper-overlaid plywood, also known as panel siding, is
sometimes used without sheathing. Paper-overlaid
plywood has many of the advantages of plywood
besides providing a satisfactory base for paint. A
medium-density overlaid plywood is not common. Stud
spacing of 16 inches requires a minimum thickness of
panel siding of three-eighths inch. However, 1/2- or
5/8-inch-thick sheets perform better because of their
greater thickness and strength.
Siding can be installed only after the window and
doorframes are installed. In order to present a uniform
appearance, the siding must line up properly with the
drip caps and the bottom of the window and door sills.
At the same time, it must lineup at the corners. Siding
must be properly lapped to increase wind resistance and
watertightness. In addition, it must be installed with the
proper nails and in the correct nailing sequence.
Standard siding sheets are 4 by 8 feet; larger sizes
are available. They must be applied vertically with
intermediate and perimeter nailing to provide the
desired rigidity. Most other methods of applying sheet
materials require some type of sheathing beneath.
Where horizontal joints are necessary, they should be
protected by simple flashing.
An exterior-grade plywood should always be used
for siding and can be obtained in grooved, brushed, and
saw-textured surfaces. These surfaces are usually
finished with stain. If shiplap or matched edges are not
provided, the joints should be waterproofed. Waterproofing often consists of caulking and a batten at each
joint and a batten at each stud if closer spacing is desired
for appearance. An edge treatment of water-repellent
preservative will also aid in reducing moisture
penetration. When plywood is being installed in sheet
form, allow a 1/16-inch edge and end spacing.
One of the most important factors in the successful
performance of various siding materials is the type of
fasteners used. Nails are the most common, and it is poor
economy to use them sparingly. Galvanized, aluminum,
and stainless steel corrosive-resistant nails may cost
more, but their use will ensure spot-free siding under
adverse conditions. Ordinary steel-wire nails should not
be used to attach siding since they tend to rust in a short
time and stain the face of the siding. In some cases, the
small-head rails will show rust spots through the putty
and paint. Noncorrosive nails that will not cause rust are
readily available.
Exterior-grade particle board might also be
considered for panel siding. Normally, a 5/8-inch
thickness is required for 16-inch stud spacing and
3/4-inch thickness for 24-inch stud spacing. The finish
must be an approved paint, and the stud wall behind
must have corner bracing.
Two types of nails are commonly used with siding:
the small-head finishing nail and the moderate-size
flathead siding roil.
Medium-density fiberboards might also be used in
some areas as exterior coverings over certain types of
sheathing. Many of these sheet materials resist the
passage of water vapor. Hence, when they are used, it is
important that a good vapor barrier, well insulated, be
used on the warm side of the insulated walls.
The small-head finishing nail is set (driven with a
nail set) about 1/16 inch below the face of the siding,
The hole is filled with putty after the prime coat of paint
has been applied. The more commonly used flathead
siding nail is nailed flush with the face of the siding and
the head later covered with paint.
If the siding is to be natural finished with a
water-repellent preservative or stain, it should be
fastened with stainless steel or aluminum nails. In some
types of prefinished sidings, nails with color-matched
heads are supplied.
Nonwood materials are used in some types of
architectural design. Stucco or a cement-plaster finish,
preferably over a wire mesh base, is common in the
Southwest and the West Coast areas. Masonry veneers
can be used effectively with wood siding in various
finishes to enhance the beauty of both materials.
Nails with modified shanks are available. These
include the annularly (ring) threaded shank nail and the
spirally threaded shank nail. Both have greater
withdrawal resistance than the smooth-shank nail, and,
for this reason, a shorter nail is often used.
Some structures require an exterior covering with
minimum maintenance. Although nonwood materials
are often chosen for this reason, the paint industry is
providing comparable long-life coatings for wood-base
materials. Plastic films on wood siding and plywood are
also promising because little or no refinishing is
necessary for the life of the building.
In siding, exposed nails should be driven flush with
the surface of the wood Overdriving may not only show
the hammer mark, but may also cause objectionable
splitting and crushing of the wood. In sidings with
prefinished surfaces or overlays, the nails should be
driven so as not to damage the finished surface.
top of the drip cap to the bottom of the sill is
61 inches. If 12-inch-wide siding is used, the
number of courses would be 61/10 = 6.1, or six
courses. To obtain the exact exposure distance,
divide 61 by 6 and the result would be 10 1/6
2. Determine the exposure distance from the
bottom of the sill to just below the top of the
foundation wall. If this distance is 31 inches, use
three courses of 10 1/3 inches each. Thus, the
exposure distance above and below the window
would be almost the same (fig. 4-3).
When this system is not satisfactory because of big
differences in the two areas, it is preferable to use an
equal exposure distance for the entire wall height and
notch the siding at the window sill. The fit should be
tight to prevent moisture from entering.
Siding may be installed starting with a bottom
course. It is normally blocked out with a starting strip
the same thickness as the top of the siding board (fig.
4-3). Each succeeding course overlaps the upper edge
of the course below it. Siding should be nailed to each
stud or on 16-inch centers. When plywood, wood
sheathing, or spaced wood nailing strips are used over
nonwood sheathing, 7d or 8d nails may be used for
3/4-inch-thick siding. However, if gypsum or fiberboard
sheathing is used, 10d nails are recommended to
properly penetrate the stud For 1/2-inch-thick siding,
nails may be 1/4 inch shorter than those used for
3/4-inch siding.
Figure 4-3.-Installation of bevel siding.
The minimum lap for bevel siding is 1 inch. The
average exposure distance is usually determined by the
distance from the underside of the window sill to the top
of the drip cap (fig. 4-3). From the standpoint of weather
resistance and appearance, the butt edge of the first
course of siding above the window should coincide with
the top of the window drip cap. In many one-story
structures with an overhang, this course of siding is
often replaced with a frieze board It is also desirable
that the bottom of a siding course be flush with the
underside of the window sill. However, this may not
always be possible because of varying window heights
and types that might be used in a structure.
The nails should be located far enough up from the
butt to miss the top of the lower siding course (fig. 4-4).
The clearance distance is usually 1/8 inch. This allows
for slight movement of the siding because of moisture
changes without causing splitting. Such an allowance is
especially required for the wider (8 to 12 inch) siding.
One system used to determine the siding exposure
width so that it is approximately equal above and below
the window sill is as follows:
It is good construction practice to avoid butt joints
whenever possible. Use the longer sections of siding
under windows and other long stretches, and use the
shorter lengths for areas between windows and doors.
When a butt joint is necessary, it should be made over a
stud and staggered between courses.
1. Divide the overall height of the window frame
by the approximate recommended exposure
distance for the siding used (4 inches for
6-inch-wide siding, 6 inches for 8-inch-wide
siding, 8 inches for 10-inch-wide siding, and 10
inches for 12-inch-wide siding). This result will
be the number of courses between the top and
the bottom of the window. For example, the
overall height of our sample window from the
Siding should be square cut to provide good joints.
Open joints permit moisture to enter and often lead to
paint deterioration. It is a good practice to brush or dip
Figure 4-4.-Nailing the siding.
widths up to 12 inches. They should be applied in the
same manner as lap or drop siding, depending on the
pattern. Prepackaged siding should be applied
according to the manufacturer’s directions.
the fresh cut ends of the siding in a water-repellent
preservative before boards are roiled in place. After the
siding is in place, it is helpful to use a small
finger-actuated oil can to apply the water-repellent
preservative to the ends and butt joints.
VERTICALLY.— Vertically applied siding and
sidings with interlapping joints should be nailed in the
same manner as those applied horizontally. However,
they should be nailed to blocking used between studs or
to wood or plywood sheathing. Blocking should be
spaced from 16 to 24 inches OC. With plywood or
nominal 1-inch board sheathing, nails should be spaced
on 16-inch centers only.
Drop siding is installed in much the same way as lap
siding except for spacing and nailing. Drop, Dolly
Varden, and similar sidings have a constant exposure
distance. The face width is normally 5 1/4 inches for
1- by 6-inch siding and 7 1/4 inches for 1- by 8-inch
siding. Normally, one or two nails should be used at each
stud, depending on the width (fig. 4-4). The length of
the nail depends on the type of sheathing used, but
penetration into the stud or through the wood backing
should beat least 1 1/2 inches.
When the various combinations of boards and
battens are used, they should also be nailed to blocking
spaced from 16 to 24 inches OC between studs, or closer
for wood sheathing. The first boards or battens should
be fastened with nails at each blocking to provide at least
1 1/2 inches of penetration. For wide underboards, two
nails spaced about 2 inches apart maybe used rather than
the single row along the center (fig. 4-2). Nails of the
top board or batten should always miss the underboards
and should not be nailed through them (fig. 4-2). In such
applications, double nails should be spaced closely to
prevent splitting if the board shrinks. It is also a good
practice to use sheathing paper, such as 15-pound
asphalt felt, under vertical siding.
There are two ways to apply nonwood siding:
horizontally and vertically. Note that these are
manufactured items. Make sure you follow the
recommended installation procedures.
HORIZONTALLY.— Horizontally applied
matched paneling in narrow widths should be
blind-nailed at the tongue with a corrosion-resistant
finishing nail (fig. 4-4). For widths greater than 6 inches,
an additional nail should be used as shown.
Exterior-grade plywood, paper-overlaid plywood,
and similar sheet materials used for siding are usually
applied vertically. The nails should be driven over the
Other materials, such as plywood, hardboard, or
medium-density fiberboard, are used horizontally in
studs, and the total effective penetration into the wood
should be at least 1 1/2 inches. For example, 3/8-inch
plywood siding over 3/4-inch wood sheathing would
require a 7d nail (which is 2 1/4 inches long). This would
result in a 1 1/8-inch penetration into the stud, but a total
effective penetration of 1 7/8 inches into the wood
The joints of all types of sheet material should be
caulked with mastic unless the joints are of the
interlapping or matched type of battens. It is a good
practice to place a strip of 15-pound asphalt felt under
The outside corners of a wood-framed structure can
be finished in several ways. Siding boards can be
miter-joined at the corners. Shingles can be edge-lapped
alternately. The ends of siding boards can be butted at
the corners and then covered with a metal cap.
Figure 4-5.-Corner board.
Corner Boards
fit tightly the full depth of the miter. You should also
treat the ends with a water-repellent preservative before
A type of corner finish that can be used with almost
any kind of outside-wall covering is called a corner
board. This corner board can be applied to the corner
with the siding or shingles end-or-edge-butted against
the board.
Metal Corners
Metal corners (fig. 4-6, view C) are perhaps more
commonly used than the mitered corner and give a
mitered effect. They are easily placed over each corner
as the siding is installed. The metal corners should fit
tightly and should be nailed on each side to the sheathing
or corner stud beneath. When made of galvanized iron,
they should be cleaned with a mild acid wash and primed
with a metal primer before the structure is painted to
prevent early peeling of the paint. Weathering of the
metal will also prepare it for the prime paint coat.
A corner board usually consists of two pieces of
stock: one piece 3 inches wide and the other 4 inches
wide if an edge-butt joint between the corner boards is
used. The boards are cut to a length that will extend from
the top of the water table to the bottom of the frieze.
They are edge-butted and nailed together before they are
nailed to the corner. This procedure ensures a good tight
joint (fig. 4-5). A strip of building paper should be tacked
over the corner before the corner board is nailed in
position (always allow an overlap of paper to cover the
subsequent crack formed where the ends of the siding
butts against the corner board).
corner boards (fig. 4-5) of various types and sizes
may be used for horizontal sidings ofaall types. They also
provide a satisfactory termination for plywood and
similar sheet materials. Vertical applications of matched
paneling or of boards and battens are terminated by
lapping one side and nailing into the edge of this
member, as well as to the nailing members beneath.
corner boards are usually 1 1/8 or 1 3/8 inches wide. To
give a distinctive appearance, they should be quite
narrow. Plain outside casing, commonly used for
window and doorframes, can be adapted for corner
Interior Corners
Interior corners (fig. 4-6, view A) are butted against
a square corner board of nominal 1 1/4- or 1 3/8-inch
size, depending on the thickness of the siding.
Mitered Corners
Mitering the corners (fig. 4-6, view B) of bevel and
similar sidings is often not satisfactory, unless it is
carefully done to prevent openings. A good joint must
Figure 4-6.-Siding details: A. Interior corners; B. Mitered corners; C. Metal corners; D. Siding return of roof.
Shingles and Shakes
extending well up on the dormer wall will provide the
necessary resistance to entry of wind-driven rain. Here
again, a water-repellent preservative should be used on
the ends of the siding at the roof line.
Prefinished shingle or shake exteriors are sometimes used with color-matched metal corners. They can
also be lapped over the adjacent corner shingle,
alternating each course. This kind of corner treatment,
called lacing, usually requires that flashing be used
At times, the materials used in the gable ends and in
the walls below differ in form and application. The
details of construction used at the juncture of the two
materials should be such that good drainage is assured.
For example, when vertical boards and battens are used
at the gable end and horizontal siding below, a drip cap
When siding returns against a roof surface, such as
at the bottom of a dormer wall, there should be a 2-inch
clearance (fig. 4-6, view D). Siding that is cut for a tight
fit against the shingles retains moisture after rains and
usually results in peeling paint. Shingle flashing
Figure 4-8.-Single coursing of sidewalls (wood shingles and
Figure 4-7.-Cable-end finish (material transition).
or similar molding should be used (fig. 4-7). Flashing
should be used over and above the drip cap so that
moisture cannot enter this transition area.
Wood shingles and shakes are applied in a singleor double-course pattern. They maybe used over wood
or plywood sheathing. When sheathing with 3/8-inch
plywood, use threaded nails. For nonwood sheathing,
1-by 3-inch or 1- by 4-inch wood nailing strips are used
as a base.
In the single-course method, one course is simply
laid over the other as lap siding is applied. The shingles
can be second grade because only one-half or less of the
butt portion is exposed (fig. 4-8). Shingles should not be
soaked before application but should usually be laid
with about 1/8- to 1/4-inch space between adjacent
shingles to allow for expansion during rainy weather.
When a siding effect is desired, shingles should be laid
so that they are in contact, but only lightly. Pre-stained
or treated shingles provide the best results.
Figure 4-9.-Double coursing of side walls (wood shingles and
The first shingles can be a lower quality. Because much
In a double-course system, the undercourse is
applied over the wall, and the top course is nailed
directly over a 1/4-to 1/2-inch projection of the butt (fig.
4-9). The first course should be nailed only enough to
hold it in place while the outer course is being applied.
of the shingle length is exposed, the top course should
be first-grade shingles.
Shingles and shakes should be applied with
rust-resistant nails long enough to penetrate into the
Figure 4-10.-Flashing of material changes: A. Stucco above, siding below, B. Vertical siding above, horizontal below.
wood backing strips or sheathing. In a single course, a
3d or 4d zinc-coated shingle nail is commonly used. In
a double course, where nails are exposed, a 5d
zinc-coated nail with a small flat head is used for the top
course, and a 3d or 4d size for the undercourse. Use
building paper over lumber sheathing.
One wall area that requires flashing is at the intersection of two types of siding materials. For example, a
stucco-finish gable end and a wood-siding lower wall
should be flashed (fig. 4-10, view A). A wood molding,
such as a drip cap, separates the two materials and is
covered by the flashing, which extends at least 4 inches
above the intersection. When sheathing paper is used, it
should lap the flashing (fig. 4-10, view A).
When a wood-siding pattern change occurs on the
same wall, the intersection should also be flashed. A
vertical board-sided upper wall with horizontal siding
below usually requires some type of flashing (fig. 4-10,
vie w B). A small space above the molding provides a
drip for rain. This will prevent paint peeling, which
could occur if the boards were in tight contact with the
molding. A drip cap (fig. 4-7) is sometimes used as a
terminating molding.
Flashing should be installed at the junction of
material changes, chimneys, and roof-wall
intersections. It should also be used overexposed doors
and windows, roof ridges and valleys, along the edge of
a pitched roof, and any other place where rain and
melted snow may penetrate.
To prevent corrosion or deterioration where unlike
metals come together, use fasteners made of the same
kind of metal as the flashing. For aluminum flashing,
use only aluminum or stainless steel nails, screws,
hangers, and clips. For copper flashing, use copper nails
and fittings. Galvanized sheet metal or terneplate should
be fastened with galvanized or stainless steel fasteners.
(Terneplate is a steel plate coated with an alloy of lead
and a small amount of tin.)
The same type of flashing as shown in figure 4-10,
view A, should be used over door and window openings
exposed to driving rain. However, window and door
heads protected by wide overhangs in a single-story
structure with a hip roof do not ordinarily require the
flashing. When building paper is used on the sidewalls,
it should lap the top edge of the flashing. To protect the
walls behind the window sill in a brick veneer exterior,
extend the flashing under the masonry sill up the
underside of the wood sill.
Flashing is also required at the junctions of an
exterior wall and a flat or low-pitched built-up roof (fig.
4-11). Where a metal roof is used, the metal is turned up
on the wall and covered by the siding. A clearance
should be allowed at the bottom of the siding to protect
against melted snow and rain.
Several types of gutters are available to carry the
rainwater to the downspouts and away from the
Figure 4-11-Flashing at the intersection of an exterior wall
and a flat or low-pitched roof.
Figure 4-12.-Parts of a metal gutter system.
Figure 4-13.-Gutters and downspouts: A. Half-round gutter;
B. “K” style gutter C. Round downspout; D. Rectangular
foundation. On flat roofs, water is often drained from
one or more locations and carried through an inside wall
to an underground drain. All downspouts connected to
an underground drain should be fitted with basket
strainers (fig. 4-1 2) at the junctions of the gutter.
Perhaps the most commonly used gutter is the type
hung from the edge of the roof or fastened to the edge
of the cornice fascia. Metal gutters may be the
half-round (fig. 4-13, view A) or “K” style (view B) and
may be made of galvanized metal, copper, or aluminum.
Some have a factory-applied enamel finish.
Downspouts are round or rectangular (fig. 4-13,
views C and D). The round type is used for the
half-round gutters. They are usually corrugated to
provide extra stiffness and strength. Corrugated patterns
are less likely to burst when plugged with ice.
On long runs of gutters, such as required around a
hip-roof structure, at least four downspouts are
desirable. Gutters should be installed with a pitch of 1
inch per 16 feet toward the downspouts. Formed or
half-round gutters are suspended with flat metal hangers
(fig. 4-14, views A and B). Spike and ferrule hangers are
also used with formed gutters (view C). Gutter hangers
should be spaced 3 feet OC.
Figure 4-14.-Gutter hangers: A. Flat metal hanger with
half-round gutter; B. Flat metal hanger with “K” style
metal gutter; C. Spike and ferrule with formed gutter.
Gutter splices, corner joints, and downspout
connections should be watertight. Downspouts should
be fastened to the wall by leaderstraps (fig. 4-12) or
hooks. One strap should be installed at the top, one at
the bottom, and one at each intermediate joint. An elbow
is used at the bottom to guide the water to a splash block
Figure 4-16.-Parts of a Six-panel door.
Figure 4-15.-Downspout installation: A. Downspout with
splash block; B. Drain to storm sewer.
is metal-faced with an insulated foam core. Solid-core
doors are used as exterior doors because of the heavy
service and the additional fireproofing. Hollow-core
doors are normally used for interior applications. Wood
doors are classified by design and method of
construction as panel or flush doors.
(fig. 4-15, view A), which carries the water away from
the foundation. The minimum length of a splash block
should be 3 feet. In some areas, the downspout drains
directly into a tile line, which carries the water to a storm
sewer (view B).
Panel Doors
Many types of exterior doors are available to
provide access, protection, safety, and privacy. Wood,
metal, plastic, glass, or a combination of these materials
are used in the manufacture of doors. The selection of
door type and material depends on the degree of
protection or privacy desired, architectural compatibility, psychological effect, fire resistance, and cost.
A panel door, or stile-and-rail door, consists of
vertical members called stiles and horizontal members
called rails. The stiles and rails enclose panels of solid
wood, plywood, louvers, or glass (fig. 4-16). The stiles
extend the full height at each side of the door. The
vertical member at the hinged side of the door is called
the hinge, or hanging, stile, and the one to which the
latch, lock, or push is attached is called the closing, or
lock, stile. Three rails run across the full width of the
door between the stiles: the top rail, the intermediate or
lock rail, and the bottom rail. Additional vertical or
horizontal members, called muntins, may divide the
door into any number of panels. The rails, stiles, and
muntins maybe assembled with either glued dowels or
mortise-and-tenon joints.
Sash Doors
Better quality exterior doors are of solid-core
construction. The core is usually fiberglass, or the door
Panel doors in which one or more panels are glass
are classed as sash (glazed) doors. Fully glazed panel
this section, you should be able to identify the
types of exterior doors and describe basic
exterior doorjamb installation procedures.
Figure 4-17.-Three types of solid-core doors.
This type of core is highly resistant to warpage and is
more dimensionally stable than the continuous-block
doors with only atop and bottom rail, without horizontal
or vertical muntins, are refereed to as “casement” or
“French doors.” Storm doors are lightly constructed
glazed doors. They are used in conjunction with exterior
doors to improve weather resistance. Combination
doors consist of interchangeable or hinged glass and
screen panels.
In addition to the solid lumber cores, there are two
types of composition solid cores. Mineral cores (see
fig. 4-17) consist of inert mineral fibers bonded into
rigid panels. The panels are framed within the wood rails
and stiles, resulting in a core that is light in weight and
little affected by moisture. Because of its low density,
this type of door should not be used where sound control
is important.
Flush Doors
Flush doors are usually made up of thin sheets of
veneer over a core of wood, particle board, or
fiberboard. The veneer faces act as stressed-skin panels
and tend to stabilize the door against warping. The face
veneer may be of ungraded hardwood suitable for a
plain finish or selected hardwood suitable for a natural
finish. The appearance of flush doors maybe enhanced
by the application of plant-on decorative panels. Both
hollow-core and solid-core doors usually have solid
internal rails and stiles so that hinges and other hardware
may be set in solid wood.
The other type (not shown) has particleboard,
flakeboard, or waferboard cores, consisting of wood
chips or vegetable fibers mixed with resins or other
binders, formed under heat and pressure into solid
panels. This type of core requires a solid-perimeter
frame. Since particleboard has no grain direction, it
provides exceptional dimensional stability and freedom
from warpage. Because of its low screw-holding ability,
it is usually desirable to install wood blocks in the core
at locations where hardware will be attached.
Two types of solid wood cores are widely used in
flush-door construction (fig. 4-17). The first type, called
a continuous-block, strip- or wood-stave core, consists
of low-density wood blocks or strips that are glued
together in adjacent vertical rows, with the end joints
staggered. This is the most economical type of solid
core. However, it is subject to excessive expansion and
contraction unless it is sealed with an impervious skin,
such as a plastic laminate.
The doorjamb is the part of the frame that fits inside
the masonry opening or rough frame opening. Jambs
may be wood or metal. The jamb has three parts: the two
side jambs and the head jamb across the top. Exterior
doorjambs have a stop as part of the jamb. The stop is
the portion of the jamb that the face of the door closes
against. The jamb is 1 1/4 inches thick with a 1/2-inch
rabbet serving as a stop.
The second type is the stile-and-rail core, in which
blocks are glued up as panels inside the stiles and rails.
thickness. If the jamb is not wide enough, strips of wood
are nailed on the edges to form an extension. Jambs may
also be custom made to accommodate various wall
Standard metal jambs are available for lath and
plaster, concrete block, and brick veneer in 4 3/4-, 5 3/4-,
6 3/4-, and 8 3/4-inch widths. For drywall construction,
the common widths available are 5 1/2 and 5 5/8 inches.
The sill is the bottom member in the doorframe. It
is usually made of oak for wear resistance. When softer
wood is used for the sill, a metal nosing and wear strips
are generally included.
The brick mold or outside casings are designed and
installed to serve as stops for the screen or combination
door. The stops are provided for by the edge of the jamb
and the exterior casing thickness (fig. 4-1 8).
Doorframes can be purchased knocked down
(K. D.) or preassembled with just the exterior casing or
brick mold applied. In some cases, they come
preassembled with the door hung in the opening. When
the doorframe is assembled on the job, nail the side
Figure 4-18.-Parts of an exterior doorframe.
Wood jambs are manufactured in two standard
widths: 5 1/4 inches for lath and plaster and 4 1/2 inches
for drywall. Jambs may be easily cut to fit walls of any
Figure 4-19.-Thresholds.
Figure 4-20.-Thresholds providing weatherproof seats.
jambs to the head jamb and sill with 10d casing nails.
Then nail the casings to the front edges of the jambs with
10d casing nails spaced 16 inches OC.
Exterior doors are 1 3/4 inches thick and not less
than 6 feet 8 inches high. The main entrance door is 3
feet wide, and the side or rear service door is 2 feet 8
inches wide. A hardwood or metal threshold (fig. 4- 19)
covers the joint between the sill and the finished floor,
The bottom of an exterior door may be equipped
with a length of hooked metal that engages with a
specially shaped threshold to provide a weatherproof
seal. Wood and metal thresholds are available with
flexible synthetic rubber tubes that press tightly
against the bottom of the door to seal out water and
cold or hot air. These applications are shown in
figure 4-20. Manufacturers furnish detailed instruction
for installation.
Of the various types of doors, the swinging door is
the most common (fig. 4-21 ). The doors are classed as
either right hand or left hand, depending on which side
is hinged. Stand outside the dear. If the hinges are on
your left-hand side, it is a left-hand door. If the hinges
are on your right, it is a right-hand door. For a door to
swing freely in an opening, the vertical edge opposite
the hinges must be beveled slightly. On a left-hand door
that swings away from the viewer, a left-hand regular
bevel is used; if the door opens toward the viewer, it has
a left-hand reverse bevel. Similarly, if the hinges are on
the right and the door swings toward the viewer, it has
a right-hand reverse bevel.
A door that swings both ways through an opening
is called a double-acting door. Two doors that are hinged
on opposite sides of a doorway and open from the center
are referred to as “double doors”; such doors are
frequently double acting. One leaf of a double door may
be equipped with an astragal— an extended lip that fits
over the crack between the two doors. A Dutch door is
one that is cut and hinged so that top and bottom portions
open and close independently.
Figure 4-21.-Determining door swings.
that places the top of the sill flush with the finished floor
Line the rough opening with a strip of 15-pound
asphalt felt paper, 10 or 12 inches wide. In some
structures, it may be necessary to install flashing over
the bottom of the opening. The assembled frame is then
set into the opening. Set the sill of the assembled
doorframe on the trimmed-out area in the floor framing,
tip the frame into place, center it horizontaly, and then
secure it with temporary braces.
Using blocking and wedges, you should level the
sill and bring it to the correct height (even with the
finished floor). Be sure the sill is level and well
supported. For masonry wall and slab floors, the sill is
usually placed on a bed of mortar.
Before installing the exterior doorframe, prepare
the rough opening to receive the frame. The opening
should be approximately 3 inches wider and 2 inches
higher than the size of the door. The sill should rest
firmly on the floor framing, which normally must be
notched to accommodate the sill. The subfloor, floor
joists, and stringer or header joist must be cut to a depth
After the installation is complete, a piece of 1/4-or
3/8- inch plywood should be lightly tacked over the sill
to protect it during further construction work. At this
time, many Builders prefer to hang a temporary door so
the interior of the structure can be secured and provide
a place to store tools and materials.
Hanging the door and installing door hardware are
a part of the interior finishing operation and will be
described later in this TRAMAN.
With the sill level, drive a 16d casing nail through
the side casing into the wall frame at the bottom of each
side. Insert blocking or wedges between the trimmer
studs and the top of the jambs. Adjust the wedges until
the frame is plumb. Use a level and straightedge for this
procedure (fig. 4-22).
A variety of prehung exterior door units are
available. They include single doors, double doors, and
doors with sidelights. Millwork plants provide detailed
instructions for installing their products.
First, check the rough opening. Make sure the size
is correct and that it is plumb, square, and level. Apply
a double bead of caulking compound to the bottom of
the opening, and set the unit in place. Spacer shims,
located between the frame and door, should not be
removed until the frame is firmly attached to the rough
Insert shims between the side jambs and trimmer
studs. They should be located at the top, bottom, and
midpoint of the door. Drive 16d finishing nails through
the jambs, shims, and into the structural frame members.
Manufacturers usually recommend that at least two of
the screws in the top hinge be replaced with 2 1/4-inch
screws. Finally, adjust the threshold so that it makes
smooth contact with the bottom edge of the door. After
a prehung exterior door unit is installed, the door should
be removed from the hinges and carefully stored. A
temporary door can be used until final completion of the
When setting doorframes, never drive any
of the nails completely into the wood until all
nails are in place and a final check has been
made to make sure that no adjustments are
this section, you should be able to identify the
types of windows used in frame structures, and
describe installation procedures.
Figure 4-22.-Plumbing an exterior doorjamb.
The primary purpose of windows is to allow the
entry of light and air, but they may also be an important
part of the architectural design of a building. Windows
and their frames are millwork units that are usually fully
assembled at the factory, ready for use in buildings.
These units often have the sash fitted and weather
stripped, frame assembled, and exterior casing in place,
Standard combination storms and screens or separate
units can also be included. Wood components are treated
with a water-repellent preservative at the factory to
Place additional wedges between the jambs and stud
frame in the approximate location of the lock strike plate
and hinges. Adjust the wedges until the side jambs are
well supported and straight. Then secure the wedges by
driving a 16d casing nail through the jamb, wedge, and
into the trimmer stud. Finally, nail the casing in place
with 16d casing nails. These nails should be placed 3/4
inch from the outer edges of the casing and spaced 16
inches OC.
Figure 4-23.-Typical double-hung window.
provide protection before and after they are placed in
the walls.
Insulated glass, used both for stationary and moveable sash, consists of two or more sheets of spaced glass
with hermetically sealed edges. It resists heat loss more
than a single thickness of glass and is often used without
a storm sash.
Window frames and sashes should be made from a
clear grade of decay-resistant heartwood stock, or from
wood that has been given a preservative treatment.
Examples include pine, cedar, cypress, redwood, and
Frames and sashes are also available in metal. Heat
loss through metal frames and sash is much greater than
through similar wood units. Glass blocks are sometimes
used for admitting light in places where transparency or
ventilation is not required.
Windows are available in many types. Each type has
its own advantage. The principal types are double-hung,
casement, stationary, awning, and horizontal sliding. In
this chapter, we’ll cover just the first three.
location. Compression weather stripping, for example,
prevents air infiltration, provides tension, and acts as a
counterbalance. Several types allow the sash to be
removed for easy painting or repair.
The jambs (sides and top of the frames) are made of
nominal 1-inch lumber; the width provides for use with
drywall or plastered interior finish. Sills are made from
nominal 2-inch lumber and sloped at about 3 inches in
12 inches for good drainage. Wooden sash is normally
1 3/8 inches thick. Figure 4-24 shows an assembled
window stool and apron.
The double-hung window is perhaps the most
familiar type of window. It consists of upper and lower
sashes (fig. 4-23 detail) that slide vertically in separate
grooves in the side jambs or in full-width metal weather
stripping. This type of window provides a maximum
face opening for ventilation of one-half the total window
area. Each sash is provided with springs, balances, or
compression weather stripping to hold it in place in any
Figure 4-24.-Window stool with apron.
Figure 4-25.-Out-swinging casement sash.
Sash may be divided into a number of lights (glass
panes or panels) by small wood members called
muntins. Some manufacturers provide preassembled
dividers, which snap in place over a single light,
dividing it into six or eight lights. This simplifies
painting and other maintenance.
Casement windows consist of side-hinged sash,
usually designed to swing outward (fig. 4-25). This type
can be made more weathertight than the in-swinging
style. Screens are located inside these out-swinging
windows, and winter protection is obtained with a storm
Assembled frames are placed in the rough opening
over strips of building paper put around the perimeter to
minimize air infiltration. The frame is plumbed and
sash or by using insulated glass in the sash. One advantage of the casement window over the double-hung type
nailed to side studs and header through the casings or
the blind stops at the sides. Where nails are exposed,
such as on the casing, use the corrosion-resistant type.
is that the entire window area can be opened for
Hardware for double-hung windows includes the
sash lifts that are fastened to the bottom rail. These are
sometimes eliminated by providing a finger groove in
the rail. Other hardware consists of sash lockss or
fasteners located at the meeting rail. They lock the
window and draw the sash together to provide a
wind-tight fit.
window, and units are usually received from the factory
Weather stripping is also provided for this type of
entirely assembled with hardware in place. Closing
hardware consists of a rotary operator and sash lock. As
in the double-hung units, casement sash can be used in
a number of ways—as a pair or in combinations of two
or more pairs. Style variations are achieved by divided
lights. Snap-in muntins provide a small, multiple-pane
Double-hung windows can be arranged in a number
of ways—as a single unit, doubled (or mullion), or in
groups or three or more. One or two double-hung
windows on each side of a large stationary insulated
window are often used to create a window wall. Such
large openings must be framed with headers large
insulating value, should be installed carefully to prevent
enough to carry roof loads.
necessary to eliminate this problem in cold climates.
appearance for traditional styling.
Metal sash is sometimes used but, because of lowcondensation and frosting on the interior surfaces during
cold weather. A full storm-window unit is sometimes
Figure 4-26.-Typical use of stationary window in combination
with other types.
Stationary windows, used alone or in combination
with double-hung or casement windows (fig. 4-26),
usually consist of a wood sash with a large single pane
of insulated glass. They are designed to provide light, as
well as be attractive, and are fastened permanently into
the frame. Because of their size (sometimes 6 to 8 feet
wide), stationary windows require a 1 3/4-inch-thick
sash to provide strength. This thickness is required
because of the thickness of the insulating glass.
Figure 4-27.-Fixed glass in wood stops.
plastics. Also included may be ceramic-coated, corrugated, figured, and silvered and other decorative glass.
Additional materials may include glazier’s points,
setting pads, glazing compounds, and other installation
Other types of stationary windows may be used
without a sash. The glass is set directly into rabbeted
frame members and held in place with stops. As with all
window-sash units, back puttying and face puttying of
the glass (with or without a stop) will assure moistureresistance windows (fig. 4-27).
Sheet or window glass is manufactured by the flat
or vertically drawn process. Because of the
manufacturing process, a wave or draw distortion runs
in one direction through the sheet. The degree of
distortion controls the usefulness of this type of glass.
For best appearance, window glass should be drawn
horizontally or parallel with the ground. To ensure this,
the width dimension is given first when you are
this section, you should be able to identify the
different types of glass, glazing materials, and
describe procedures for cutting, glazing, and
installing glass.
It is surprising how many types of glass and glasslike materials are used in construction. Each has its own
characteristics, advantages, and best uses. In this
section, we’ll cover the various types of glass and
materials, and the methods used in assembling glass
features (“glazing”).
Plate glass is similar to window and heavy-sheet
glass. The surface, rather than the composition or
thickness, is the distinguishing feature. Plate glass is
manufactured in a continuous ribbon and then cut into
large sheets. Both sides of the sheet are ground and
polished to a perfectly flat plane. Polished plate glass is
furnished in thicknesses or from 1/8 inch to 1 1/4 inches.
Thicknesses 5/16 inch and over are termed “heavy
polished plate.” Regular polished plate is available in
three qualities: silvering, mirror glazing, and glazing.
The glazing quality is generally used where ordinary
glazing is required. Heavy polished plate is generally
available in commercial quality only.
The “Glass and Glazing” section of construction
specifications contains a wide range of materials. These
may include sheet glass, plate glass, heat- and
glare-reducing glass, insulating glass, tempered glass,
laminated glass, and various transparent or translucent
Heat Absorbing
Heat-absorbing glass contains controlled quantities
of a ferrous iron admixture that absorbs much of the
energy of the sun. Heat-absorbing glass is available in
plate, heavy plate, sheet, patterned, tempered, wired,
and laminated types. Heat-absorbing glass dissipates
much of the heat it absorbs, but some of the heat is
retained. Thus, heat-absorbing glass may become much
hotter than ordinary plate glass.
Because of its higher rate of expansion, heatabsorbing glass requires careful cutting, handling, and
glazing. Sudden heating or cooling may induce edge
stresses, which can result in failure if edges are
improperly cut or damaged. Large lights made of
heat-absorbing glass that are partially shaded or heavily
draped are subject to higher working stresses and
require special design consideration.
Glare Reducing
Glare-reducing glass is available in two types. The
first type is transparent with a neutral gray or other color
tint, which lowers light transmission but preserves true
color vision. The second type is translucent, usually
white, which gives wide light diffusion and reduces
glare. Both types absorb some of the sun’s radiant
energy and therefore have heat-absorbing qualities. The
physical characteristics of glare-reducing glass are quite
similar to those of plate glass. Although glare-reducing
glass absorbs heat, it does not require the special
precautions that heat-absorbing glass does.
spacers should be provided for uniform clearances on
all units set with face stops, Use metal glazing strips for
1/2-inch-thick sash without face stops. Use a full bed of
glazing compound in the edge clearance on the bottom
of the sash and enough at the sides and top to make a
weathertight seal. It is essential that the metal channel
at the perimeter of each unit be covered by at least 1/8
inch of compound. This ensures a lasting seal.
Tempered glass is plate or patterned glass that has
been reheated to just below its melting point and then
cooled very quickly by subjecting both sides to jets of
air. This leaves the outside surfaces, which cool faster,
in a state of compression. The inner portions of the glass
are in tension. As a result, fully tempered glass has three
to five times the strength against impact forces and
temperature changes than untempered glass has.
Tempered glass chipped or punctured on any edge or
surface will shatter and disintegrate into small blunt
pieces. Because of this, it cannot be cut or drilled.
Heat Strengthened
Heat-strengthened glass is plate glass or patterned
glass with a ceramic glaze fused to one side. Preheating
the glass to apply the ceramic glaze strengthens the glass
considerably, giving it characteristics similar to
tempered glass. Heat-strengthened glass is about twice
as strong as plate glass. Like tempered glass, it cannot
be cut or drilled.
Heat-strengthened glass is available in thicknesses
of 1/4 and 5/16 inch and in limited standard sizes. It is
opaque and is most often used for spandrel glazing in
curtain wall systems. Framing members must be sturdy
and rigid enough to support the perimeter of the
tempered glass panels. Each panel should rest on
resilient setting blocks. When used in operating doors
and windows, it must not be handled or opened until the
glazing compound has set.
Insulating glass units consist of two or more sheets
of glass separated by either 3/16-, 7/32-, or 1/4-inch air
space. These units are factory-sealed. The captive air is
dehydrated at atmospheric pressure. The edge seal can
be made either by fusing the edges together or with
metal spacing strips. A mastic seal and metal edge
support the glass.
Insulating glass requires special installation precautions. Openings into which insulating glass is
installed must be plumb and square. Glazing must be
free of paint and paper because they can cause a heat
trap that may result in breakage. There must be no direct
contact between insulating glass and the frame into
which it is installed. The glazing compound must be a
nonhardening type that does not contain any materials
that will attack the metal-to-glass seal of the insulating
glass. Never use putty. Resilient setting blocks and
Wired glass is produced by feeding wire mesh into
the center of molten glass as it is passed through a pair
of rollers. A hexagonal, diamond-shaped square, or
rectangular pattern weld or twisted wire mesh may be
used. To be given afire rating, the mesh must be at least
25 gauge, with openings no larger than 1 1/8 inches.
Also, the glass must be no less than 1/4 inch thick. Wired
glass may be etched or sandblasted on one or both sides
protected with a coat of shellac, varnish, paint, or metal
(usually copper). Mirrors used in building construction
are usually either polished plate glass or tempered plate
to soften the light or provide privacy. It may be obtained
with a pattern on one or both sides.
Proper installation requires that the weight of the
mirror be supported at the bottom. Mastic installation is
not recommended because it may cause silver spoilage.
Patterned glass has the same composition as
window and plate glass. It is semitransparent with
distinctive geometric or linear designs on one or both
sides. The pattern can be impressed during the rolling
process or sandblasted or etched later. Some patterns are
also available as wired glass. pattern glass allows entry
of light while maintaining privacy. It is also used for
decorative screens and windows. Patterned glass must
be installed with the smooth side to the face of the putty.
Sheets made of thermoplastic acrylic resin
(Plexiglas®and Luciteo, both trade names) are available
in flat and corrugated sheets. This material is readily
formed into curved shapes and, therefore, is often used
in place of glass. Compared with glass, its surface is
more readily scratched; hence, it should be installed in
out-of-reach locations. This acrylic plastic is obtainable
in transparent, translucent, or opaque sheets and in a
wide variety of colors.
Laminated glass is composed of two or more layers
of either sheet or polished plate glass with one or more
layers of transparent or pigmented plastic sandwiched
between the layers. A vinyl plastic, such as plasticized
polyvinyl resin butyl 0.015 to 0.025 inch thick, is
generally used. Only the highest quality sheet or
polished plate glass is used in making laminated glass.
When this type of glass breaks, the plastic holds the
pieces of glass and prevents the sharp fragments from
shattering. When four or more layers of glass are
laminated with three or more layers of plastic, the
product is known as bullet-resisting glass. Safety glass
has only two layers of glass and one of plastic.
In this section, we’ll discuss the various types of
sealers you’ll need to install, hold fast, and seal a
window in its setting.
Wood-Sash Putty
Wood-sash putty is a cement composed of fine
powdered chalk (whiting) or lead oxide (white lead)
mixed with boiled or raw linseed oil. Putty may contain
other drying oils, such as soybean or perilla. As the oil
oxides, the putty hardens. Litharge (an oxide of lead) or
special driers may be added if rapid hardening is
required. Putty is used in glazing to set sheets of glass
into frames. Special putty mixtures are available for
interior and exterior glazing of aluminum and steel
window sash.
Safety glass is available with clear or pigmented
plastic, and either clear or heat-absorbing and
glare-reducing glass. Safety glass is used where strong
impact may be encountered and the hazard of flying
glass must be avoided. Exterior doors with a pane area
greater than 6 square feet and shower tubs and
enclosures are typical applications.
A good grade of wood-sash putty resists sticking to
the putty knife or glazier’s hands, yet it should not be
too dry to apply to the sash. In wood sash, apply a
suitable primer, such as priming paints or boiled linseed
Glazing compounds must be compatible with the
layers of laminated plastic. Some compounds cause
deterioration of the plastic in safety glass.
Putty should not be painted until it has thoroughly
set. Painting forms an airtight film, which slows the
drying. This may cause the surface of the paint to crack
All putty should be painted for proper protection.
Mimers are made with polished plate, window,
sheet, and picture glass. The reflecting surface is a thin
coat of metal, generally silver, gold, copper, bronze, or
chromium, applied to one side of the glass. For special
mirrors, lead, aluminum, platinum, rhodium, or other
metals may be used. The metal film can be semitransparent or opaque and can be left unprotected or
Metal-Sash Putty
Metal-sash putty differs from wood putty in that it
is formulated to adhere to nonporous surfaces. It is used
for glazing aluminum and steel sash either inside or
outside. It should be applied as recommended by the
manufacturer. Metal-sash putty should be painted
within 2 weeks after application, but should be
thoroughly set and hard before painting begins.
There are two grades of metal-sash putty: one for
interior and one for exterior glazing. Both wood-sash
putty and metal-sash putty are known as oleoresinous
caulking compounds. The advantage of these materials
is their low cost; their disadvantages include high
shrinkage, little adhesion, and an exposed life
expectancy of less than 5 years.
working time of the material (2 to 3 hours). Toluene and
xylene are good solvents for this purpose.
Rubber Materials
Rubber compression materials are molded in
various shapes. They are used as continuous gaskets and
as intermittent spacer shims. A weathertight joint
requires that the gasket be compressed at least 15
percent. Preformed materials reduce costs because
careful cleaning of the glass is not necessary, and there
is no waste of material.
Elastic Compounds
Elastic glazing compounds are specially formulated
from selected processed oils and pigments, which
remain plastic and resilient over a longer period than the
common hard putties. Butyl and acrylic compounds are
the most common elastics. Butyl compounds tend to
stain masonry and have a high shrinkage factor.
Acrylic-based materials require heating to 110°F before
application. Some shrinkage occurs during curing. At
high temperatures, these materials sag considerably in
vertical joints. At low temperatures, acrylic-based
materials become hard and brittle. The y are available in
a wide range of colors and have good adhesion qualities.
Always measure the length and width of the opening
in which the glass is to fit at more than one place.
Windows are often not absolutely square. If there is a
difference between two measurements, use the smaller
and then deduct 1/8 inch from the width and length to
allow for expansion and contraction. Otherwise, the
glass may crack with changes of temperature. This is
especially true with steel casement windows.
Polybutane Tape
Polybutane tape is a nondrying mastic, which is
available in extruded ribbon shapes. It has good
adhesion qualities, but should not be used as a substitute
or replacement for spacers. It can be used as a continuous bed material in conjunction with a polysulfide
sealer compound. This tape must be pressure applied for
proper adhesion.
Cutting glass is a matter of confidence-and
experience. You can gain both by practicing on scrap
glass before trying to cut window glass to size.
Equipment required for glass cutting consists of a glass
cutter, a flat, solid table, a tape measure, and a wood or
metal T-square or straightedge. Look at figure 4-28. You
should lightly oil the cutting wheel (view A) with a thin
machine oil or lubricating fluid. Hold the cutter by
resting your index finger on the flat part of the handle,
as shown in view B.
To cut a piece of glass, lay a straightedge along the
proposed cut, as shown in view C. Hold it down firmly
with one hand and with the glass cutter in the other,
make one continuous smooth stroke along the surface
of the glass with the side of the cutter pressed against
the straightedge (view D). The objective is to score the
glass, not cut through it. You should be able to hear the
cutter bite into the glass as it moves along. Make sure
the cut is continuous and that you have not skipped any
section. Going over a cut is a poor practice as the glass
is sure to break away at that point. Snap the glass
immediately after cutting by placing a pencil or long
dowel under the score line and pressing with your hands
on each side of the cut (view E). Frosted or patterned
glass should be cut on the smooth side. Wire-reinforced
glass can be cut the same as ordinary glass, except that
you will have to separate the wires by flexing the two
pieces up and down until the wire breaks or by cutting
the wires with side-cutting pliers.
Polysulfide Compounds
Polysulfide-base products are two-part synthetic
rubber compounds based on a polysulfide polymer. The
consistency of these compounds after mixing is similar
to that of a caulking compound. The activator must be
thoroughly mixed with the base compound at the job.
The mixed compound is applied with either a caulking
gun or spatula. The sealing surfaces must be extremely
clean. Surrounding areas of glass should be protected
before glazing. Excess and spilled material must be
removed and the surfaces cleaned promptly. Once
polysulfide elastomer glazing compound has cured, it is
very difficult to remove. Any excess material left on the
surfaces after glazing should be cleaned during the
Figure 4-28.-Glass cutting.
the waste. Do not nibble without first scoring a line. You
can smooth off the edges of glass intended for shelving
or tabletops with an oilstone dipped in water, as shown
in view I. Rub the stone back and forth from end to end
with the stone at a 45° angle to the glass. Rub the stone
side to side only, not up and down.
To cut a narrow strip from a large piece of glass,
score a line and then tap gently underneath the score line
with the cutter to open up an inch or so of the score line
(view F). Next, grasp the glass on each side of the line
and gently snap off the waste piece (view G). Press
downward away from the score mark. If the strip does
not break off cleanly, nibble it off with the pliers (view
H) or the notches in the cutter. Slivers less than 1/2 inch
wide are cut off by scoring the line and then nibbling off
No attempt should be made to change the size of
heat-strengthened, tempered, or doubled-glazed units,
since any such effort will result in permanent damage.
Table 4-1.-Weight and Maximum Sizes of Sheet Glass
Table 4-2.-Grades of Sheet Glass
All heat-absobing glass must be clean cut. Nibbling to
remove flares or to reduce oversized dimensions of
heat-absorbing glass is not permitted.
The maximum size glass that may be used in a
particular location is governed to a great extent by wind
load. Wind velocities, and consequently wind pressures,
increase with height above the ground. Various building
codes or project specifications determine the maximum
allowable glass area for wind load.
Sheet glass is produced in a number of thicknesses,
but only 3/32- and 1/8-inch sheets are commonly used
as a window glass. These thicknesses are designated,
respectively, as single strength (SS) and double strength
(DS). Thick sheet glass, manufactured by the same
method as window glass, is used in openings that exceed
window-glass-size recommendations. Table 4-1 lists
the thicknesses, weights, and recommended maximum
sizes. Sheet glass comes in six grades (table 4-2).
Attach the sash so that it will withstand the design
load and comply with the specifications. Adjust, plumb,
and square the sash to within 1/8 inch of nominal
dimensions on shop drawings. Remove all rivets,
screws, bolts, nail heads, welding fillets, and other
projections from specified clearances. Seal all sash
corners and fabrication intersections to make the sash
watertight. Put a coat of primer paint on all sealing
surfaces of wood sash and carbon steel sash. Use
appropriate solvents to remove grease, lacquers, and
other organic-protecting finishes from sealing surfaces
of aluminum sash.
On old wood sashes, you must clean all putty runs
of broken glass fragments and glazier’s points—
triangular pieces of zinc or galvanized steel driven into
the rabbet. Remove loose paint and putty by scraping.
Wipe the surface clean with a cloth saturated in mineral
spirits or turpentine; prime the putty runs and allow them
to dry.
On new wood sashes, you should remove the dust,
prime the putty runs, and allow them to dry. All new
wood sashes should be pressure treated for decay
Figure 4-29.-Types of wood-sash glazing.
On old metal sashes, you must remove loose paint
or putty by scraping. Use steel wool or sandpaper to
remove rust. Clean the surfaces thoroughly with a cloth
saturated in mineral spirits or turpentine. Prime bare
metal and allow it to dry thoroughly.
into the sash or frame to receive and support panes of
glass. The glass is held tightly against the frame by
glazier’s points. The rabbet is then filled with putty. The
putty is pressed firmly against the glass and beveled
back against the wood frame with a putty knife. A
priming paint is essential in glazing wood sash. The
priming seals the pores of the wood, preventing the loss
of oil from the putty. Wood frames are usually glazed
from the outside (fig. 4-29).
On new metal sashes, you should wipe the sash
thoroughly with a cloth saturated in mineral spirits or
turpentine to remove dust, dirt, oil, or grease. Remove
any rust with steel wool or sandpaper. If the sash is not
already factory-primed, prime it with rust-inhibitive
paint and allow it to dry thoroughly.
As we noted earlier, wood-sash putty is generally
made with linseed oil and a pigment. Some putties
contain soybean oil as a drying agent. Putty should not
be painted until it is thoroughly set. A bead of putty or
glazing compound is applied between the glass and the
frame as a bedding. The bedding is usually applied to
the frame before the glass is set. Back puttying is then
used to force putty into spaces that may have been left
between the frame and the glass.
“Glazing” refers to the installation of glass in
prepared openings of windows, doors, partitions, and
curtain walls. Glass may be held in place with glazier’s
points, spring clips, or flexible glazing beads. Glass is
kept from contact with the frame with various types of
shims. Putty, sealants, or various types of caulking
compounds are applied to make a weathertight joint
between the glass and the frame.
Metal Windows and Doors
Glass set in metal frames must be prevented from
making contact with metal. This may be accomplished
by first applying a setting bed of metal-sash putty or
glazing compound. Metal-sash putty differs from
wood-sash putty in that it is formulated to adhere to a
Wood Sash
Most wood sash is face-glazed. The glass is
installed in rabbets, consisting of L-shaped recesses cut
compound after it is placed, while the interior remains
soft. This type of glazing compound is used in windows
or doors subject to twisting or vibration. It may be
painted as soon as the surface has formed.
For large panes of glass, setting blocks may be
placed between the glass edges and the frame to
maintain proper spacing of the glass in the openings. The
blocks may be of wood, lead, neoprene, or some flexible
material. For large openings, flexible shims must be set
between the face of the glass and the glazing channel to
allow for movement. Plastics and heat-absorbing or
reflective glass require more clearance to allow for
greater expansion. The shims may be in the form of a
continuous tape of a butyl-rubber-based compound,
which has been extruded into soft, tacky, ready-to-use
tape that adheres to any clean, dry surface. The tape is
applied to the frame and the glass-holding stop before
the glass is placed in a frame. Under compression, the
tape also serves as a sealant.
Glass may be held in place in the frame by spring
clips inserted in holes in the metal frame or by
continuous angles or stops attached to the frame with
screws or snap-on spring clips. The frames of metal
windows are shaped either for outside or inside glazing.
Do not glaze or reglaze exterior sash when the
temperature is 40°F or lower unless absolutely
necessary. Sash and door members must be thoroughly
cleaned of dust with a brush or cloth dampened with
turpentine or mineral spirits. Lay a continuous
1/6-inch-thick bed of putty or compound in the putty run
(fig. 4-31). The glazed face of the sash can be
recognized as the size on which the glass was cut. If the
glass has a bowed surface, it should be set with the
concave side in. Wire glass is set with the twist vertical.
Press the glass firmly into place so that the bed putty
will fill all irregularities.
Figure 4-30.-Types of metal-sash glazing.
When glazing wood sash, insert two glazier’s points
per side for small lights and about 8 inches apart on all
sides for large lights. When glazing metal sash, use wire
clips or metal glazing beads.
nonporous surface. Figure 4-30 shows examples of the
types of metal-sash putty. Elastic glazing compounds
may be used in place of putty. These compounds are
After the glass has been bedded, lay a continuous
bead of putty against the perimeter of the glass-face
putty run. Press the putty with a putty knife or glazing
tool with sufficient pressure to ensure its complete
adhesion to the glass and sash. Finish with full, smooth,
accurately formed bevels with clean-cut miters. Trim up
produced from processed oils and pigments and will
remain plastic and resilient over a longer period than
will putty. A skin quickly forms over the outside of the
Figure 4-31.—Setting glass with glazier’s points and putty.
the bed putty on the reverse side of the glass. When
glazing or reglazing interior sash and transoms and
interior doors, you should use wood or metal glazing
beads. Exterior doors and hinged transoms should have
glass secured in place with inside wood or metal glazing
beads bedded in putty. In setting wired glass for security
purposes, set wood or metal glazing beads, and secure
with screws on the side facing the area to be protected.
Depending on weather conditions, the time for skinning
over may be 2 to 10 days. Type II metal-sash putty can
usually be painted within 2 weeks after placing. This
putty should not be painted before it has hardened
because early painting may retard the set.
Clean the glass on both sides after painting. A cloth
moistened with mineral spirits will remove putty stains.
When scrapers are used, care should be exercised to
avoid breaking the paint seal at the putty edge.
Weed-sash putty should be painted as soon as it has
surface-hardened. Do not wait longer than 2 months
after glazing. When painting the glazing compound,
overlap the glass 1/16 inch as a seal against moisture.
After installing large glass units in buildings under
construction, it is considered good practice to place a
large “X” on the glass. Use masking tape or washable
paint. This will alert workers so they will not walk into
the glass or damage it with tools and materials.
For metal sashes, use type 1 metal sash elastic
compound. Metal-sash putty should be painted
immediatel y after a firm skin has formed on the surface.
Basic Roof Framing, Benjamin Barnow, Tab Books,
Inc., Blue Ridge Summit, Pa., 1986.
Design of Wood Frame Structures for Permanence,
National Forest Products Association, Washington,
D.C., 1988.
Although the following references
were current when this TRAMAN was
published, their continued currency
cannot be assured. You therefore need
to ensure that you are studying the
latest revisions.
Exterior and Interior Trim, John E. Ball, Delmar Pub.,
Albany, N.Y., 1975.
Modern Carpentry, Willis H. Wagner, GoodheartWILCOX Co., South Holland, Ill., 1983.
paneling, and similar types are also used. Many of these
drywall finishes come prefinished.
Builders are responsible for finishing the interior of
the buildings of a construction project. Interior finish
consists mainly of the coverings of the rough walls,
ceilings, and floors, and installing doors and windows
with trim and hardware. In this chapter, we’ll discuss
wall and ceiling coverings, including the closely related
topics of insulation and ventilation. In the next chapter,
we’ll look at floor coverings, stairway construction, and
interior door and wood trim installation.
The use of thin sheet materials, such as gypsum
board or plywood, requires that studs and ceiling joists
have good alignment to provide a smooth, even surface.
Wood sheathing often corrects misaligned studs on
exterior walls. A strongback (fig. 5-1) provides for
alignment of ceiling joists of unfinished attics. It can
also be used at the center of a span when ceiling joists
are uneven.
Gypsum wallboard is the most commonly used wall
and ceiling covering in construction today. Because
gypsum is nonflammable and durable, it is appropriate
for application inmost building types. Sheets of drywall
are nailed or screwed into place, and nail indentions or
“dimples” are filled with joint compound. Joints
between adjoining sheets are built up with special tape
and several layers (usually three) of joint compound.
Drywall is easily installed, though joint work can be
this section, you should be able to describe
drywall installation and finishing procedures,
and identify various types of wall and ceiling
coverings and the tools, fasteners, and
accessories used in installation.
Though lath-and-plaster finish is still used in
building construction today, drywall finish has become
the most popular. Drywall finish saves time in
construction, whereas plaster finish requires drying time
before other interior work can be started. Drywall finish
requires only short drying time since little, if any, water
is required for application. However, a gypsum drywall
demands a moderately low moisture content of the
framing members to prevent “nail-pops.” Nail-pops
result when frame members dry out to moisture
equilibrium, causing the nailhead to form small
“humps” on the surface of the board. Stud alignment is
also important for single-layer gypsum finish to prevent
a wavy, uneven appearance. Thus, there are advantages
to both plaster and gypsum drywall finishes and each
should be considered along with the initial cost and
Drywall varies in composition, thickness, and edge
shape. The most common sizes with tapered edges are
1/2 inch by 4 feet by 8 feet and 1/2 inch by 4 feet by
12 feet.
Regular gypsum board is commonly used on walls
and ceilings and is available in various thicknesses. The
most common thicknesses are 1/2 inch and 5/8 inch.
Type X gypsum board has special additives that make it
fire resistant.
There are many types of drywall. One of the most
widely used is gypsum board in 4- by 8-foot sheets.
Gypsum board is also available in lengths up to 16 feet.
These lengths are used in horizontal application.
Plywood, hardboard, fiberboard, particleboard, wood
Figure 5-1.—Strongback for alignment of ceiling joists.
Drywall of 5/8-inch thickness is favored for quality
single-layer walls, especially where studs are 24 inches
OC. Use 5/8-inch drywall for ceiling joists 24 inches
OC, where sheets run parallel to joists. This thickness is
widely used in multiple, fire-resistant combinations.
MR (moisture resistant) or WR (water resistant)
board is also called greenboard and blueboard. Being
water resist ant, this board is appropriate for bathrooms,
laundries, and similar areas with high moisture. It also
provides a suitable base for embedding tiles in mastic.
MR or WR board is commonly 1/2 inch thick.
There are several types of edging in common use.
Tapered allows joint tape to be bedded and built up to a
flat surface. This is the most common edge used.
Tapered round is a variation on the first type. Tapered
round edges allow better joints. These edges are more
easily damaged, however. Square makes an acceptable
exposed edge. Beveled has an edge that, when left
untapped, gives a paneled look.
Sound-deadening board is a sublayer used with
other layers of drywall (usually type X); this board is
often 1/4 inch thick
Backing board has a gray paper lining on both sides.
It is used as a base sheet on multilayer applications.
Backing board is not suited for finishing and decorating.
Foil-backed board serves as a vapor barrier on
exterior walls. This board is available in various
Commonly used tools in drywall application
include a tape measure, chalk line, level, utility and
drywall knives, straightedge, and a 48-inch T square
(drywall square) or framing square. Other basic tools
include a keyhole saw, drywall hammer (or convex head
hammer), screw gun, drywall trowel, comer trowel, and
a foot lift. Some of these tools are shown in figure 5-2.
Vinyl-surfaced board is available in a variety of
colors. It is attached with special drywall finish nails and
is left exposed with no joint treatment.
Plasterboard or gypsum lath is used for plaster base.
It is available in thickness starting at 3/8 inch, widths 16
and 24 inches, and length is usually 48 inches. Because
it comes in manageable sizes, it’s widely used as a
plaster base instead of metal or wood lath for both new
construction and renovation. This material is not
compatible with portland cement plaster.
The tape measure, chalk line, and level are used for
layout work. The utility and drywall knives,
straightedge, and squares are used for scoring and
breaking drywall. The keyhole saw is used for cutting
irregular shapes and openings, such as outlet box
openings. A convex head or drywall, hammer used for
drywall nails will “dimple” the material without tearing
the paper. The screw gun quickly sinks drywall screws
to the adjusted depth and then automatically disengages.
The varying lengths of drywall allow you to lay out
sheets so that the number of seams is kept to a minimum,
End points can be a problem, however, since the ends of
the sheets aren’t shaped (only the sides are). As sheet
length increases, so does weight, unwieldiness, and the
need for helpers. Standard lengths are 8, 9, 10, 12, and
14 feet. Sixteen-foot lengths are also available. Use the
thickness that is right for the job. One-half-inch drywall
is the dimension most commonly used. That thickness,
which is more than adequate for studs 16 inches on
center (OC), is also considered adequate where studs are
24 inches OC. Where ceiling joists are 16 inches OC,
use 1/2-inch drywall, whether it runs parallel or
perpendicular to joists. Where ceiling joists are 24
inches OC, though, use 1/2-inch drywall only if the
sheets are perpendicular to joists.
Drywall knives have a variety of uses. The 6-inch
knife is used to bed the tape in the first layer of joint
compound and for filling nail or screw dimples. The
12-inch finishing knife “feathers out” the second layer
of joint compound and is usually adequate for the third
or “topping” layer. Knives 16 inches and wider are used
for applying the topping coat. Clean and dry drywall
knives after use. Use only the drywall knives for the
purpose intended-to finish drywall.
The drywall trowel resembles a concrete finishing
trowel and is manufactured with a 3/16-inch concave
bow. This trowel, also referred to as a “flaring,”
“feathering,” or “bow” trowel, is used when applying
the finish layer of joint compound. A comer trowel is
almost indispensable for making clean interior comers.
Drywall of 1/4- and 3/8-inch thicknesses is used
effectively in renovation to cover existing finish walls
with minor irregularities. Neither is adequate as a single
layer for walls or ceiling, however. Two 1/4-inch-thick
plies are also used to wrap curving walls.
For sanding dried joint compound smooth, use 220
grit sandpaper. Sandpaper should be wrapped around a
sanding block or can be used on an orbital sander. When
Figure 5-2.—Common tools for drywall installation.
the longer nail is subject to the expansion and
contraction of a greater depth of wood.
Smooth-shank, diamond-head nails are commonly
used to attach two layers of drywall; for example, when
fireproofing a wall. Again, the mil length should be
selected carefully. Smooth-shank nails should penetrate
the base wood 1 inch. Predecorated drywall nails, which
may be left exposed, have smaller heads and are
color-matched to the drywall.
SCREWS.— Drywall screws (fig. 5-3, view B) are
the preferred method of fastening among professional
builders, cabinetmakers, and renovators. These screws
are made of high-quality steel and are superior to
conventional wood screws. Use a power screw gun or
an electric drill to drive in the screws. Because this
method requires no impact, there is little danger of
jarring loose earlier connections. There are two types of
drywall screws commonly used: type S and type W.
Figure 5-3.—Drywall fasteners.
Type S.— Type S screws (fig. 5-3, view B) are
designed for attachment to metal studs. The screws are
self-tapping and very sharp, since metal studs can flex
away. At least 3/8 inch of the threaded part of the screw
should pass through a metal stud. Although other lengths
are available, 1-inch type S screws are commonly used
for single-ply drywall.
sanding, ensure you’re wearing the required personnel
protective gear to prevent dust inhalation.
A foot lift helps you raise and lower drywall sheets
while you plumb the edges. Be careful when using the
foot lift—applying too much pressure to the lift can
easily damage the drywall.
Type W.— Type W screws (fig. 5-3, view B) hold
drywall to wood. They should penetrate studs or joists
at least 5/8 inch. If you are applying two layers of
drywall, the screws holding the second sheet need to
penetrate the wood beneath only 1/2 inch.
Which fasteners you use depends in part upon the
material underneath. The framing is usually wood or
metal studs, although gypsum is occasionally used as a
base. Adhesives are normally used in tandem with
screws or nails. This allows the installer to use fewer
screws or nails, leaving fewer holes that require filling.
For reasons noted shortly, you’ll find the drywall screw
the most versatile fastener for attaching drywall to
framing members.
TAPE.— Joint tape varies little. The major
difference between tapes is whether they are perforated
or not. Perforated types are somewhat easier to bed and
cover. New self-sticking fiber-mesh types (resembling
window screen) are becoming popular. Having the mesh
design and being self-sticking eliminates the need for
the first layer of bedding joint compound.
JOINT COMPOUND.— Joint compound comes
ready-mixed or in powder form. The powder form must
be mixed with water to a putty consistency.
Ready-mixed compound is easier to work with, though
its shelf life is shorter than the powdered form. Joint
compounds vary according to the additive they contain.
Always read and follow the manufacturer’s
NAILS.— Drywall nails (fig. 5-3, view A) are
specially designed, with oversized heads, for greater
holding power. Casing or common nailheads are too
small. Further, untreated nails can rust and stain a finish.
The drywall nail most frequently used is the annular ring
nail. This nail fastens securely into wood studs and
joists. When purchasing such nails, consider the
thickness of the layer or layers of drywall, and allow
additional length for the nail to penetrate the underlying
wood 3/4 inch. Example: 1/2-inch drywall plus 3/4-inch
penetration requires a 1 1/4-inch nail. A longer nail does
not fasten more securely than one properly sized, and
ADHESIVES.— Adhesives are used to bond
single-ply drywall directly to the framing members,
furring strips, masonry surfaces, insulation board, or
other drywall. They must be used with nails or screws.
Figure 5-4.—Corner and casing beads.
Because adhesives are matched with specific materials,
be sure to select the correct adhesive for the job. Read
and follow the manufacturer’s directions.
specified. Casing beads are matched to the thickness of
the drywall used.
When laying out a drywall job, keep in mind that
each joint will require taping and sanding. You therefore
should arrange the sheets so that there will be a
minimum of joint work. Choose drywall boards of the
maximum practical length.
A number of metal accessories have been developed
to finish off or protect drywall. corner beads (fig. 5-4)
are used on all exposed comers to ensure a clean finish
and to protect the drywall from edge damage. corner
bead is nailed or screwed every 5 inches through the
drywall and into the framing members. Be sure the
corner bead stays plumb as you fasten it in place. Casing
beads (fig. 5-4), also called stop beads, are used where
drywall sheets abut at wall intersections, wall and
exposed ceiling intersections, or where otherwise
Drywall can be hung with its length either parallel
or perpendicular to joists or studs. Although both
arrangements work sheets running perpendicular afford
better attachment. In double-ply installation, run base
sheets parallel and top sheets perpendicular. For walls,
the height of the ceiling is an important factor. When
Figure 5-5.—Single-layer application of drywall.
ceilings are 8 feet 1 inch high or less, run wall sheets
horizontally. Where they are higher, run wall sheets
vertically, as shown in figure 5-5.
First, don’t order drywall too far in advance.
Drywall must be stored flat to prevent damage to the
edges, and it takes up a lot of space.
The sides of drywall taper, but the ends don’t, so
there are some layout constraints. End joints must be
staggered where they occur. Such joints are difficult to
feather out correctly. Where drywall is hung vertically,
Second, to cut drywall (fig. 5-6), you only need to
cut through the fine-paper surface (view A). Then, grasp
the smaller section and snap it sharply (view B). The
gypsum core breaks along the scored line. Cut through
the paper on the back (view C).
avoid side joints within 6 inches of the outside edges of
doors or windows. In the case of windows, the bevel on
the side of the drywall interferes with the finish trim,
and the bevel may be visible. To avoid this difficulty, lay
out vertical joints so they meet over a cripple (shortened)
Third, when cutting a piece to length, never cut too
closely. One-half-inch gaps are acceptable at the top and
the bottom of a wall because molding covers these gaps.
If you cut too closely, you may have difficulty getting
the piece into place. Also, where walls aren’t square, you
may have to trim anyway.
stud toward the middle of a door or window opening.
When installing drywall horizontally and an
impact-resistant joint is required, you should use nailing
blocks (fig. 5-5).
Fourth, snap chalk lines on the drywall to indicate
joists or stud centers underneath attachment is much
quicker. Remember: Drywall edges must be aligned
over stud, joist, or rafter centers.
Fifth, when cutting out holes for outlet boxes,
fixtures, and so on, measure from the nearest fixed
point(s); for example, from the floor or edge of the next
piece of drywall. Take two measurements from each
There are several things you can do to make
working with drywall easier.
Figure 5-7.—Spacing for single and double nailing of gypsum
or screws must fasten securely in a framing member. If
a nail misses the framing, pull it out, dimple the hole,
and fill it in with compound; then try again. If you drive
a nail in so deep that the drywall is crushed, drive in
another reinforcing nail within 2 inches of the first.
When attaching drywall sheets, nail (or screw) from
the center of the sheet outward. Where you double-nail
sheets, single nail the entire sheet first and then add the
second (double) nails, again beginning in the middle of
the sheet and working outward.
Figure 5-6.—Cutting gypsum drywall
point, so you get the true height and width of the cutout.
Locate the cutout on the finish side of the drywall. To
start the cut, either drill holes at the corners or start cuts
by stabbing the sharp point of the keyhole saw through
the drywall and then finishing the cutting with a keyhole
or compass saw. It is more difficult to cut a hole with
just a utility knife, but it can be done.
single- or double-nailed. Single nails are spaced a
maximum of 8 inches apart on walls and 7 inches apart
on ceilings. Where sheets are double-nailed, the centers
of nail pairs should be approximately 12 inches apart.
Space each pair of nails 2 to 2 1/2 inches apart. Do not
double-nail around the perimeter of a sheet. Instead, nail
as shown in figure 5-7. As you nail, it is important that
you dimple each nail; that is, drive each nail in slightly
below the surface of the drywall without breaking the
surface of the material. Dimpling creates a pocket that
can be filled with joint compound. Although special
When attaching drywall, hold it firmly against the
framing to avoid nail-pops and other weak spots. Nails
Figure 5-8.—Dimpling of gypsum drywall.
Ceilings can be covered by one person using two
tees made from 2 by 4s. This practice is acceptable when
dealing with sheets that are 8 foot in length. Sheets over
this length will require a third tee, which is very
awkward for one individual to handle. Two people
should be involved with the installation of drywall on
convex-headed drywall hammers are available for this
operation, a conventional claw hammer also works
(fig. 5-8).
attach more securely, fewer are needed. Screws are
usually spaced 12 inches OC regardless of drywall
thickness. On walls, screws maybe placed 16 inches OC
for greater economy, without loss of strength. Don’t
double up screws except where the first screw seats
poorly. Space screws around the edges the same as nails.
WALLS.— Walls are easier to hang than ceilings,
and it’s something one person working alone can do
effectively, although the job goes faster if two people
work together. As you did with the ceiling, be sure the
walls have sufficient blocking in corners before you
applied to wood studs allows you to bridge minor
irregularities along the studs and to use about half the
number of nails. When using adhesives, you can space
the nails 12 inches apart (without doubling up). Don’t
alter nail spacing along end seams, however. To attach
sheets to studs, use a caulking gun and run a 3/8-inch
bead down the middle of the stud. Where sheets meet
over a framing member, run two parallel beads. Don’t
make serpentine beads, as the adhesive could ooze out
onto the drywall surface. If you are laminating a second
sheet of drywall over a fret, roll a liquid contact cement
with a short-snap roller on the face of the sheet already
in place. To keep adhesive out of your eyes, wear
goggles. When the adhesive turns dark (usually within
30 minutes), it is ready to receive the second piece of
drywall. Screw on the second sheet as described above.
Make sure the first sheet on a wall is plumb and its
leading edge is centered over a stud. Then, all you have
to do is align successive sheets with the first sheet. The
foot lift shown earlier in figure 5-2 is useful for raising
or lowering a sheet while you level its edge. After you’ ve
sunk two or three screws or nails, the sheet will stay in
place. A gap of 1/2 inch or so along the bottom of a sheet
is not critical; it is easily covered by finish flooring,
baseboards, and soon. If you favor a clean, modem line
without trim, manufactured metal or vinyl edges (casing
beads) are available for finishing the edges.
During renovation, you may find that hanging
sheets horizontally makes sense. Because studs in older
buildings often are not on regular centers, the joints of
vertical sheets frequently do not align with the studs.
Again, using the foot lift, level the top edge of the bottom
sheet. Where studs are irregular, it’s even more
important that you note positions and chalk line stud
centers onto the drywall face before hanging the sheet.
CEILINGS.— Begin attaching sheets on the
ceiling, first checking to be sure extra blocking (that will
receive nails or screws) is in place above the top plates
of the walls. By doing the ceiling first, you have
maximum exposure of blocking to nail or screw into. If
there are gaps along the intersection of the ceiling and
wall, it is much easier to adjust wall pieces.
Figure 5-9.—Finishing drywall joints.
Applying drywall in older buildings yields a lot of
waste because framing is not always standardized. Use
the cutoffs in such out-of-the-way places as closets.
Don’t piece together small sections in areas where you’ll
notice seams. Never assume that ceilings are square with
walls. Always measure from at least two points, and cut
between coats prevents rework that has a cost involved
as well as extra time.
Where sheets of drywall join, the joints are covered
with joint tape and compound (fig. 5-9). The procedure
is straightforward.
1. Spread a swath of bedding compound about 4
inches wide down the center of the joint (fig. 5-9,
view A). Press the tape into the center of the joint
with a 6-inch finish knife (fig. 5-9, view B).
Apply another coat of compound over the first
to bury the tape (fig. 5-9, view C). As you apply
the compound over the tape, bear down so you
take up any excess. Scrape clean any excess,
however, as sanding it off can be tedious.
Drywall is quite good for creating or covering
curved walls. For the best results, use two layers or
1/4-inch drywall, hung horizontally. The framing
members of the curve should be placed at intervals of
no more than 16 inches OC; 12 inches is better. For an
8-foot sheet applied horizontally, an arc depth of 2 to 3
feet should be no problem, but do check the
manufacturer’s specifications. Sharper curves may
require backcutting (scoring slots into the back so that
the sheet can be bent easily) or wetting (wet-sponging
the front and back of the sheet to soften the gypsum).
Results are not always predictable, though. When
applying the second layer of 1/4-inch drywall, stagger
the vertical butt joints.
2. When the first coat is dry, sand the edges with
fine-grit sand paper while wearing personalprotective equipment. Using a 12-inch knife,
apply a topping of compound 2 to 4 inches wider
than the first applications (view D).
3, Sand the second coat of compound when it is
dry. Apply the third and final coat, feathering it
out another 2 to 3 inches on each side of the joint.
You should be able to do this with a 12-inch
knife, Otherwise, you should use a 16-inch
“feathering trowel.”
The finishing of gypsum board drywall is generally
a three-coat application. Attention to drying times
Figure 5-10.—Finishing an inside corner.
lightly and apply a second coat, feathering edges 2 to 3
inches beyond the first coat. A third coat maybe needed,
depending on your coverage. Feather the edges of each
coat 2 or 3 inches beyond each preceding coat. Corner
beads are no problem if you apply compound with care
and scrape the excess clean. Nail holes and screw holes
usually can be covered in two passes, though shrinkage
sometimes necessitates three. A tool that works well for
sanding hard-to-reach places is a sanding block on an
extension pole; the block has a swivel-head joint.
When finishing an inside corner (fig. 5-10), cut your
tape the length of the corner angle you are going to
finish. Apply the joint compound with a 4-inch knife
evenly about 2 inches on each side of the angle. Use
sufficient compound to embed the tape. Fold the tape
along the center crease (view A) and firmly press it into
the corner. Use enough pressure to squeeze some
compound under the edges. Feather the compound 2
inches from the edge of the tape (view B). When the first
coat is dry, apply a second coat. A corner trowel (view
C) is almost indispensable for taping comers. Feather
the edges of the compound 1 1/2 inches beyond the first
coat. Apply a third coat if necessary, let it dry, and sand
it to a smooth surface. Use as little compound as possible
at the apex of the angle to prevent hairline cracking.
When molding is installed between the wall and ceiling
intersection, it is not necessary to tape the joint (view D).
When finishing an outside corner (fig. 5-1 1), be sure
the corner bead is attached firmly. Using a 4-inch
finishing knife, spread the joint compound 3 to 4 inches
wide from the nose of the bead, covering the metal
edges. When the compound is completely dry, sand
Figure 5-11.—Finishing an outside corner.
To give yourself the greatest number of decorating
options in the future, paint the finished drywall surface
with a coat of flat oil-base primer. Whether you intend
to wallpaper or paint with latex, oil-base primer adheres
best to the facing of the paper and seals it.
Renovation and Repair
For the best results, drywall should be flat against
the surface to which it is being attached. How flat the
nailing surface must be depends upon the desired finish
effect. Smooth painted surfaces with spotlights on them
require as nearly flawless a finish as you can attain.
Similarly, delicate wall coverings-particularly those
with close, regular patterns—accentuate pocks and
lumps underneath. Textured surfaces are much more
forgiving. In general, if adjacent nailing elements (studs,
and so forth) vary by more than 1/4 inch, buildup low
spots. Essentially, there are three ways to create a flat
nailing surface:
Figure 5-12.—Furring strips hacked with shims.
the center of each stud on the existing surface. Here too,
mark the depth of low spots.
The objective of this process is a flat plane of furring
strips over existing studs. Tack the strips in place and
add shims (wood shingles are best) at each low spot
marked (see fig. 5-12). To make sure a furring strip
doesn’t skew, use two shims, with their thin ends
reversed, at each point. Tack the shims in place and
plumb the furring strips again. When you are satisfied,
drive the nails or screws all the way in.
Frame out a new wall-a radical solution. If the
studs of partition walls are buckled and warped,
it’s often easier to rip the walls out and replace
them. Where the irregular surface is a loadbearing wall, it maybe easier to build a new wall
within the old.
Cover imperfections with a layer of 3/8-inch
drywall. This thickness is flexible yet strong.
Drywall of 1/4-inch thickness may suffice.
Single-ply cover-up is a common renovation
strategy where existing walls are ungainly but
basically flat. Locate studs beforehand and use
screws long enough to penetrate studs and joists
at least 5/8 inch.
When attaching the finish sheets, use screws or nails
long enough to penetrate through furring strips and into
the studs behind. Strips directly over studs ensure the
strongest attachment. Where finish materials are not
sheets—for example, single-board vertical paneling—
furring should run perpendicular to the studs.
Regardless of type, finish material must be backed
firmly at all nailing pints, corners, and seams. Where
you cover existing finish surfaces or otherwise alter the
thickness of walls, it’s usually necessary to build up
existing trim. Figure 5-13 shows how this might be done
Build up the surface by “furring out.” In the
“furring - out” procedure, furring-strips 1 by 2
inches are used. Some drywall manufacturers,
however, consider that size too light for
attachment, favoring instead a nominal size of 2
by 2 inches. Whatever size strips you use, make
sure they (and the shims underneath) are
anchored solidly to the wall behind.
By stretching strings taut between diagonal comers,
you can get a quick idea of any irregularities in a wall.
If studs are exposed, further assess the situation with a
level held against a straight 2 by 4. Hold the straightedge
plumb in front of each stud and mark low spots every
12 inches or so. Using a builder’s crayon, write the depth
of each low spot, relative to the straightedge, on the stud.
If studs aren’t exposed, locate each stud by test drilling
and inserting a bent coat hanger into the hole. Chalk line
Figure 5-13.—Building up an intertor window casing.
Figure 5-14.—Repairing a large hole In drywall.
for a window casing. Electrical boxes must also be
extended with box extensions or plaster rings.
Masonry surfaces must be smooth, clean, and dry.
Where the walls are below grade, apply a vapor barrier
of polyethylene (use mastic to attach it) and install the
furring strips. Use a power-actuated nail gun to attach
strips to the masonry. Follow all safety procedures. If
you hand nail, drive case-hardened nails into the mortar
joints. Wear goggles; these nails can fragment.
Most drywall blemishes are caused by structural
shifting or water damage. Correct any underlying
problems before attacking the symptoms.
Figure 5-15.—Battens used for paneling joints.
Popped-up nails are easily fixed by pulling them out
or by dimpling them with a hammer. Test the entire wall
for springiness and add roils or screws where needed.
Within 2 inches of a popped-up nail, drive in another
nail. Spackle both when the spots are dry, then sand and
feather the compound approximately 16 inches, or
more. If the original drywall is 1/2 inch thick use
3/8-inch plasterboard as a replacement on the backing
To repair cracks in drywall, cut back the edges of
the crack slightly to remove any crumbly gypsum and
to provide a good depression for a new filling of joint
compound. Feather the edges of the compound. When
dry, sand and prime them.
Holes larger than 8 inches should be cut back to the
centers of the nearest studs. Although you should have
no problem nailing a replacement piece to the studs, the
top and the bottom of the new piece must be backed. The
best way to install backing is to screw drywall gussets
(supports) to the back of the existing drywall. Then, put
the replacement piece in the hole and screw it to the
When a piece of drywall tape lifts, gently pull until
the piece rips free from the part that’s still well stuck.
Sand the area affected and apply anew bed of compound
for a replacement piece of tape. The self-sticking tape
mentioned earlier works well here. Feather all edges.
If a sharp object has dented the drywall, merely sand
around the cavity and fill it with spackling compound.
A larger hole (bigger than your fist) should have a
backing. One repair method is shown in figure 5-14.
First, cut the edges of the hole clean with a utility knife
(view A). The piece of backing should be somewhat
larger than the hole itself. Drill a small hole into the
middle of the backing piece and thread a piece of wire
into the hole. This wire allows you to hold the piece of
backing in place. Spread mastic around the edges of the
backing. When the adhesive is tacky, fit the backing
diagonally into the hole (view B) and, holding onto the
wire, pull the piece against the back side of the hole.
When the mastic is dry, push the wire back into the wall
cavity. The backing stays in place. Now, fill the hole with
plaster or joint compound (view C) and finish (view D).
(Note: This is just one of several options available for
repairing large surface damage to gypsum board.)
Most of the plywood used for interior walls has a
factory-applied finish that is tough and durable.
Manufacturers can furnish prefinished matching
trim and molding that is also easy to apply.
Color-coordinated putty sticks are used to conceal nail
Joints between plywood sheets can be treated in a
number of ways. Some panels are fabricated with
machine-shaped edges that permit almost perfect joint
concealment. Usually, it is easier to accentuate the joints
with grooves or use battens and strips. Some of the many
different styles of battens are shown in figure 5-15.
Before installation, the panels should become
adjusted (conditioned) to the temperature and humidity
of the room. Carefully remove prefinished plywood
from cartons and stack it horizontally. Place 1-inch
spacer strips between each pair of face-to-face panels.
Do this at least 48 hours before application.
Compound sags in holes that are too big. If it
happens, mastic a replacement piece of drywall to the
backing piece. To avoid a bulge around the filled-in hole,
Plan the layout carefully to reduce the amount of
cutting and the number of joints. It is important to align
pattern. Panels for wall application are usually 1/4 inch
panels with openings whenever possible. If finished
panels are to have a grain, stand the panels around the
walls and shift them until you have the most pleasing
effect in color and grain patterns. To avoid mix-ups,
number the panels in sequence after their position has
been established.
Since hardboard is made from wood fibers, the
panels expand and contract slightly with changes in
humidity. They should be installed when they are at their
maximum size. The panels tend to buckle between the
studs or attachment points if installed when moisture
content is low. Manufacturers of prefinished hardboard
panels recommend that they be unwrapped and placed
separately around the room for at least 48 hours before
When cutting plywood panels with a portable saw,
mark the layout on the back side. Support the panel
carefully and check for clearance below. Cut with the
saw blade upward against the panel face. This
minimizes splintering. This procedure is even more
important when working with prefinished panels.
Procedures and attachment methods for hardboard
are similar to those for plywood. Special adhesives are
available as well as metal or plastic molding in matching
colors. You should probably drill nail holes for the
harder types.
Plywood can be attached directly to the wall studs
with nails or special adhesives. Use 3/8-inch plywood
for this type of installation. When studs are poorly
aligned or when the installation is made over an existing
surface in poor condition, it is usually advisable to use
furring. Nail 1- by 3- or 1- by 4-inch furring strips
horizontally across the studs. Start at the floor line and
continue up the wall. Spacing depends on the panel
thickness. Thin panels need more support. Install
vertical strips every 4 feet to support panel edges. Level
uneven areas by shimmying behind the furring strips.
Prefinished plywood panels can be installed with special
adhesive. The adhesive is applied and the panels are
simply pressed into place; no sustained pressure is
Plastic laminates are sheets of synthetic material
that are hard, smooth, and highly resistant to scratching
and wear. Although basically designed for table and
countertops, they are also used for wainscoting and wall
paneling in buildings.
Since plastic laminate material is thin (1/32 to 1/16
inch), it must be bonded to other supporting panels.
Contact bond cement is commonly used for this
purpose. Manufacturers have recently developed
prefabricated panels with the plastic laminate already
bonded to a base or backer material. This base consists
of a 1/32-inch plastic laminate mounted on 3/8-inch
particleboard. Edges are tongue and grooved so that
units can be blind-nailed into place. Various matching
corner and trim moldings are available.
Begin installing panels at a corner. Scribe and trim
the edges of the first panel so it is plumb. Fasten it in
place before fitting the next panel. Allow approximately
1/4-inch clearance at the top and bottom. After all panels
are in place, use molding to cover the space along the
ceiling. Use baseboards to conceal the space at the floor
line. If the molding strips, baseboards, and strips used
to conceal panel joints are not prefinished, they should
be spray painted or stained a color close to the tones in
the paneling before installation.
Solid wood paneling makes a durable and attractive
interior wall surface and may be appropriately used in
nearly any type of room. Several species of hardwood
and softwood are available. Sometimes, grades with
numerous knots are used to obtain a special appearance.
Defects, such as the deep fissures in pecky cypress, can
also provide a dramatic effect.
On some jobs, 1/4-inch plywood is installed over a
base of 1/2-inch gypsum wallboard. This backing is
recommended for several reasons. It tends to bring the
studs into alignment. It provides a rigid finished surface.
And, it improves the fire-resistant qualities of the wall.
(The plywood is bonded to the gypsum board with a
compatible adhesive.)
The softwood species most commonly used include
pine, spruce, hemlock and western red cedar. Boards
range in widths from 4 to 12 inches (nominal size) and
are dressed to 3/4 inch. Board and batten or shiplap
joints are sometimes used, but tongue-and-groove
(T&G) joints combined with shaped edges and surfaces
are more popular.
Through special processing, hardboard (also called
fiberboard) can be fabricated with a very low moisture
absorption rate. This type is often scored to form a tile
Exterior wall constructions, where the interior
surface consists of solid wood paneling, should include
a tight application of building paper located close to the
backside of the boards. This prevents the infiltration of
wind and dust through the joints. In cold climates,
insulation and vapor barriers are important. Base,
corner and ceiling trim can be used for decorative
purposes or to conceal irregularities in joints.
this section, you should be able to identify the
materials used to install a suspended
acoustical ceiling and explain the methods of
Figure 5-16.—Vertical wood paneling.
When solid wood paneling is applied horizontally,
furring strips are not required-the boards are nailed
directly to-the studs. Inside corners are formed by
butting the paneling units flush with the other walls. If
random widths are used, boards on adjacent walls must
match and be accurately aligned.
Vertical installations require furring strips at the top
and bottom of the wall and at various intermediate
spaces. Sometimes, 2- by 4-inch blocking is installed
between the studs to serve as a nailing base (see fig.
5-16). Even when heavy T&G boards are used, these
nailing members should not be spaced more than 24
inches apart.
Narrow widths (4 to 6 inches) of T&G paneling are
blind-nailed (see insert in fig. 5-16). The nailheads do
not appear on finished surfaces, and you eliminate the
need for countersinking and filling nail holes. This
nailing method also provides a smooth, blemish-free
surface. This is especially important when clear finishes
are used. Drive 6d finishing nails at a 45° angle into the
base of the tongue and on into the bearing point.
Carefully plumb the first piece installed and check for
the plumbness at regular intervals. For lumber paneling
(not tongue and grooved), use 6d casing or finishing
nails. Use two roils at each nailing member for panels
6 inches or less in width and three nails for wider panels.
Suspended acoustical ceiling systems can be
installed to lower a ceiling, finish off exposed joints,
cover damaged plaster, or make any room quieter and
brighter. The majority of the systems available are
primarily designed for acoustical control. However,
many manufacturers offer systems that integrate the
functions of lighting, air distribution, fire protection,
and acoustical control. Individual characteristics of
acoustical tiles, including sound-absorption coefficients, noise-reduction coefficients, light-reflection
values, flame resistance, and architectural applications,
are available from the manufacturer.
Tiles are available in 12-to 30-inch widths, 12-to
60-inch lengths, and 3/16- to 3/4-inch thicknesses. The
larger sizes are referred to as “panels.” The most
commonly used panels in suspended ceiling systems are
the standard 2-by 2-foot and 2- by 4-foot acoustic panels
composed of mineral or cellulose fibers.
It is beyond the scope of this training manual to
acquaint you with each of the suspended acoustical
ceiling systems in use today. Just as the components of
these systems vary according to manufacturers, so do
the procedures involved in their installation. With this
in mind, the following discussion is designed to acquaint
you with the principles involved in the installation of a
typical suspended acoustical ceiling system.
The success of a suspended ceiling project, as with
any other construction project, is as dependent on
planning as it is on construction methods and
procedures. Planning, in this case, involves the selection
of a grid system (either steel or aluminum), the selection
and layout of a grid pattern, and the determination of
Figure 5-17.—Grid system components.
material requirements. Figure 5-17 shows the major
components of a steel and aluminum ceiling grid system
used for the 2- by 2-foot or 2- by 4-foot grid patterns
shown in figure 5-18.
Pattern Layout
The layout of a grid pattern and the material
requirements are based on the ceiling measurements and
the length and width of the room at the new ceiling
height. If the ceiling length or width is not divisible by
2 (that is, 2 feet), increase those dimensions to the next
higher dimension divisible by 2. For example, if a
ceiling measures 13 feet 7 inches by 10 feet 4 inches,
the dimensions should be increased to 14 by 12 feet for
material and layout purposes. Next, draw a layout on
graph paper. Make sure the main tees run perpendicular
to the joists. Position the main tees on your drawing so
the border panels at room edges are equal and as large
as possible. Try several layouts to see which looks best
with the main tees. Draw in cross tees so the border
panels at the room ends are equal and as large as
possible. Try several combinations to determine the
Figure 5-18.—Grid layout for main tees.
best. For 2- by 4-foot patterns, space cross tees 4 feet
apart. For 2- by 2-foot patterns, space cross tees 2 feet
apart. For smaller areas, the 2- by 2-foot pattern is
Material Requirements
As indicated in figure 5-17, wall angles and main
tees come in 12-foot pieces. Using the perimeter of a
room at suspended ceiling height, you cart determine the
number of pieces of wall angle by dividing the perimeter
by 12 and adding 1 additional piece for any fraction.
Determine the number of 12-foot main tees and 2-foot
or 4-foot cross tees by counting them on the grid pattern
Figure 5-20.—Corner treatment.
eyelets. Before attaching the first wire, measure the
distance from the wall to the first main tee. Then, stretch
a guideline from an opposite wall angle to show the
correct position of the first nail tee. Position suspension
wires for the first tee along the guide. Wires should be
Figure 5-19.—Wall angle installation.
cut to proper length, at least 2 inches longer than the
distance between the old and new ceiling, Attach
additional wires at 4-foot intervals. Pull wires to remove
kinks and make 90° bends in the wires where they
intersect the guideline. Move the guideline, as required,
for each row. After the suspension wires are attached,
layout. In determining the number of 2-foot or 4-foot
cross tees for border panels, you must remember that no
more than 2 border tees can be cut from one cross tee.
The tools normally used to install a grid system
include a hammer, chalk or pencil, pliers, tape measure,
screwdriver, hacksaw, knife, and tin snips. With these,
you begin by installing the wall angles, then the
suspension wires, followed by the main tees, cross tees,
and acoustical panels.
the next step is to install the main tees.
In an acoustical ceiling, the panels rest on metal
members called tees. The tees are suspended by wires.
Wall Angles
The first step is to install the wall angles at the new
ceiling height. This can be as close as 2 inches below
the existing ceiling. Begin by marking a line around the
entire room to indicate wall angle height and to serve as
a level reference. Mark continuously to ensure that the
lines at intersecting walls meet. On gypsum board,
plaster, or paneled walls, install wall angles (fig. 5-19)
with nails, screws, or toggle bolts. On masonry walls,
use anchors or concrete nails spaced 24 inches apart.
Make sure the wall angle is level. Overlap or miter the
wall angle at corners (fig. 5-20). After the wall angles are
installed the next step is to attach the suspension wires.
Suspension Wires
Suspension wires are required every 4 feet along
main tees and on each side of all splices (see fig. 5-21).
Attach wires to the existing ceiling with nails or screw
Figure 5-21.—Suspenslon wire installation.
Figure 5-23.—Main tee and aluminum tee splice.
Figure 5-22.—Main tee suspension and steel splice.
MAIN TEES.— Install maintees of 12 feet or less
by resting the ends on opposite wall angles and inserting
the suspension wires (top view of fig. 5-22). Hang one
wire near the middle of the main tee, level and adjust the
wire length, then secure all wires by making the
necessary turns in the wire.
For main tees over 12 feet, cut them so the cross tees
do not intersect the main tee at a splice joint. Begin the
installation by resting the cut end on the wall angle and
attaching the suspension wire closest to the opposite
end. Attach the remaining suspension wires, making
sure the main tee is level before securing. The remaining
tees are installed by making the necessary splices (steel
splices are shown in fig. 5-22 and those for aluminum
in 5-23) and resting the end on the opposite wall angle.
After the main tees are installed, leveled, and secured,
install the cross tees.
Figure 5-24.—Aluminum cross tee assembly.
and rest the cut end on the wall angle. If the border edge
is less than half the length of the cross tee, use the
remaining portion of the border of the previously cut tee.
Steel cross tees have the same tab on both ends and,
like the aluminum tees, do not require tools for
installation. The procedures used in their installation are
the same as those just described for aluminum. A steel
cross tee assembly is shown in figure 5-25. The final
step after completion of the grid system is the
installation of the acoustical panels.
CROSS TEES.— Aluminum cross tees have
“high” and ‘low” tab ends that provide easy positive
installation without tools. Installation begins by cutting
border tees (when necessary) to fit between the first
main tee and the wall angle. Cut off the high tab end and
rest this end in the main tee slot. Repeat this procedure
until all border tees are installed on one side of the room.
Continue across the room, installing the remaining cross
tees according to your grid pattern layout. An aluminum
cross tee assembly is shown in figure 5-24. At the
opposite wall angle, cut off the low tab of the border tee
Acoustical Panels
Panel installation is started by inserting all full
ceiling panels. Border panels should be installed last,
after they have been cut to proper size. To cut a panel,
turn the finish side up, scribe with a sharp utility knife,
and saw with a 12- or 14-point handsaw.
Since ceiling panels are prefinished, handle them
with care. Keep their surfaces clean by using talcum
powder on your hands or by wearing clean canvas
gloves. If panels do become soiled, use an art gum eraser
to remove spots, smudges, and fingerprints. Some
panels can be lightly washed with a sponge dampened
with a mild detergent solution. However, before washing
or performing other maintenance services, such as
painting, refer to the manufacturer’s instructions.
Ceiling Tile
Ceiling tile can be installed in several ways,
depending on the type of ceiling or roof construction.
When a flat-surfaced backing is present, such as
between beams of a beamed ceiling in a low-slope roof,
tiles are fastened with adhesive as recommended by the
manufacturer. A small spot of a mastic type of construction adhesive at each corner of a 12-by 12-inch tile
is usually sufficient. When tile is edge-matched, stapling
is also satisfactory.
Perhaps the most common method of installing
ceiling tile uses wood strips nailed across the ceiling
joists or roof trusses (fig. 5-26, view A). These are
Figure 5-25.—Steel cross tee assembly.
Most ceiling panel patterns are random and do not
require orientation. However, some fissured panels are
designed to be installed in a specific direction and are
so marked on the back with directional arrows. When
installing panels on a large project, you should work
from several cartons. The reason for this is that the color,
pattern, or texture might vary slightly; and by working
from several cartons, you avoid a noticeable change in
Figure 5-26.—Ceiling tile assembly.
are filled or partially filled with material having a high
insulating value, the stud space has many times the
insulating ability of the air alone.
spaced a minimum of 12 inches OC. A nominal 1- by
3-inch or 1- by 4-inch wood member can be used for
roof or ceiling members spaced not more than 24 inches
OC. A nominal 2- by 2-inch or 2- by 3-inch member
should be satisfactory for truss or ceiling joist spacing
of up to 48 inches.
Commercial insulation is manufactured in a variety
of forms and types, each with advantages for specific
uses. Materials commonly used for insulation can be
grouped in the following general classes: (1) flexible
insulation (blanket and batt); (2) loose-fill insulation;
(3) reflective insulation; (4) rigid insulation (structural
and nonstructural); and (5) miscellaneous types.
In locating the strips, first measure the width of the
room (the distance parallel to the direction of the ceiling
joists). If, for example, this is 11 feet 6 inches, use ten
12-inch-square tiles and 9-inch-wide tile at each side
edge. The second wood strips from each side are located
so that they center the first row of tiles, that can now be
ripped to a width of 9 inches. The last row will also be
9 inches, but do not rip these tiles until the last row is
reached so that they fit tightly. The tile can be fitted and
arranged the same way for the ends of the room.
The insulating value of a wall varies with different
types of construction, kinds of materials used in
construction, and types and thicknesses of insulation. As
we just mentioned, air spaces add to the total resistance
of a wall section to heat transmission, but an air space
is not as effective as the same space filled with an
insulating material.
Ceiling tiles normally have a tongue on two adjacent
sides and a groove on the opposite adjacent sides. Start
with the leading edge ahead and to the open side so that
it can be stapled to the nailing strips. A small finish nail
or adhesive should be used at the edge of the tiles in the
first row against the wall. Stapling is done at the leading
edge and the side edge of each tile (fig. 5-26, view B).
Use one staple at each wood strip at the leading edge
and two at the open side edge. At the opposite wall, a
small finish nail or adhesive must again be used to hold
the tile in place.
Flexible insulation is manufactured in two types:
blanket and batt. Blanket insulation (fig. 5-27, view A)
is furnished in rolls or packages in widths to fit between
studs and joists spaced 16 and 24 inches OC. It comes
in thicknesses of 3/4 inch to 12 inches. The body of the
blanket is made of felted mats of mineral or vegetable
fibers, such as rock or glass wool, wood fiber, and
cotton. Organic insulations are treated to make them
resistant to fire, decay, insects, and vermin. Most blanket
insulation is covered with paper or other sheet material
with tabs on the sides for fastening to studs or joists. One
covering sheet serves as a vapor barrier to resist
movement of water vapor and should always face the
warm side of the wall. Aluminum foil, asphalt, or plastic
laminated paper is commonly used as barrier materials.
Most ceiling tile of this type has a factory finish;
painting or finishing is not required after it is placed.
Take care not to mar or soil the surface.
this section, you should be able to identify the
types of insulation and describe the methods of
Batt insulation (fig. 5-27, view B) is also made of
fibrous material preformed to thicknesses of 3 1/2 to
12 inches for 16-and 24-inch joist spacing. It is supplied
with or without a vapor barrier. One friction type of
fibrous glass batt is supplied without a covering and is
designed to remain in place without the normal fastening
The inflow of heat through outside walls and roofs
in hot weather or its outflow during cold weather is a
major source of occupant discomfort. Providing heating
or cooling to maintain temperatures at acceptable limits
for occupancy is expensive. During hot or cold weather,
insulation with high resistance to heat flow helps save
energy. Also, you can use smaller capacity units to
achieve the same heating or cooling result, an additional
Loose Fill
Loose-fill insulation (fig. 5-27, view C) is usually
composed of materials used in bulk form, supplied in
bags or bales, and placed by pouring, blowing, or
packing by hand. These materials include rock or glass
Most materials used in construction have some
insulating value. Even air spaces between studs resist
the passage of heat. However, when these stud spaces
Reflective insulation used in conjunction with
foil-backed gypsum drywall makes an excellent vapor
barrier. The type of reflective insulation shown in figure
5-27, view D, includes a reflective surface. When
properly installed, it provides an airspace between other
Rigid insulation (fig. 5-27, view E) is usually a
fiberboard material manufactured in sheet form. It is
made from processed wood, sugar cane, or other
vegetable products. Structural insulating boards, in
densities ranging from 15 to 31 pounds per cubic foot,
are fabricated as building boards, roof decking,
sheathing, and wallboard. Although these boards have
moderately good insulating properties, their primary
purpose is structural.
Roof insulation is nonstructural and serves mainly
to provide thermal resistance to heat flow in roofs. It is
called slab or block insulation and is manufactured in
rigid units 1/2 inch to 3 inches thick and usually 2- by
4-foot sizes.
Figure 5-27.—Types of insulation.
wool, wood fibers, shredded redwood bark cork wood
pulp products, vermiculite, sawdust, and shavings.
In building construction, perhaps the most common
forms of rigid insulation are sheathing and decorative
covering in sheet or in tile squares. Sheathing board is
made in thicknesses of 1/2 and 25/32 inch. It is coated
or impregnated with an asphalt compound to provide
water resistance. Sheets are made in 2- by 8-foot sizes
for horizontal application and 4- by 8-foot (or longer)
sizes for vertical application.
Fill insulation is suited for use between first-floor
ceiling joists in unheated attics. It is also used in
sidewalls of existing houses that were not insulated
during construction. Where no vapor barrier was
installed during construction, suitable paint coatings, as
described later in this chapter, should be used for vapor
barriers when blow insulation is added to an existing
Some insulations are not easily classified, such a
insulation blankets made up of multiple layers of
corrugated paper. Other types, such as lightweight
vermiculite and perlite aggregates, are sometimes used
in plaster as a means of reducing heat transmission.
Other materials in this category are foamed-in-place
insulations, including sprayed and plastic foam types.
Sprayed insulation is usually inorganic fibrous material
blown against a clean surface that has been primed with
an adhesive coating. It is often left exposed for
acoustical as well as insulating properties.
Most materials have the property of reflecting
radiant heat, and some materials have this property to a
very high degree. Materials high in reflective properties
include aluminum foil, copper, and paper products
coated with a reflective oxide. Such materials can be
used in enclosed stud spaces, attics, and similar
locations to retard heat transfer by radiation. Reflective
insulation is effective only where the reflective surface
faces an air space at least 3/4 inch deep. Where this
surface contacts another material, the reflective
properties are lost and the material has little or no
insulating value. Proper installation is the key to
obtaining the best results from the reflective insulation.
Reflective insulation is equally effective whether the
reflective surface faces the warm or cold side.
Expanded polystyrene and urethane plastic forms
can be molded or foamed in place. Urethane insulation
can also be applied by spraying. Polystyrene and
urethane in board form can be obtained in thicknesses
from 1/2 to 2 inches.
Ventilation of attic and roof spaces is an important
adjunct to insulation. Without ventilation, an attic space
may become very hot and hold the heat for many hours.
Ventilation methods suggested for protection against
cold-weather condensation apply equally well to
protection against excessive hot-weather roof
The use of storm windows or insulated glass greatly
reduces heat loss. Almost twice as much heat loss occurs
through a single glass as through a window glazed with
insulated glass or protected by a storm sash. Double
glass normally prevents surface condensation and frost
forming on inner glass surfaces in winter. When
excessive condensation persists, paint failures and
decay of the sash rail can occur.
In most climates, all walls, ceilings, roofs, and
floors that separate heated spaces from unheated spaces
should be insulated. This reduces heat loss from the
structure during cold weather and minimizes air
conditioning during hot weather. The insulation should
be placed on all outside walls and in the ceiling. In
structures that have unheated crawl spaces, insulation
should be placed between the floor joists or around the
wall perimeter.
If a blanket or batt insulation is used, it should be
well supported between joists by slats and a galvanized
wire mesh, or by a rigid board. The vapor barrier should
be installed toward the subflooring. Press-fit or friction
insulations fit tightly between joists and require only a
small amount of support to hold them in place.
Reflective insulation is often used for crawl spaces,
but only dead air space should be assumed in calculating
heat loss when the crawl space is ventilated. A ground
cover of roll rooting or plastic film, such as polyethylene, should be placed on the soil of crawl spaces to
decrease the moisture content of the space as well as of
the wood members.
Insulation should be placed along all walls, floors,
and ceilings that are adjacent to unheated areas. These
include stairways, dwarf (knee) walls, and dormers of 1
1/2 story structures. Provisions should be made for
ventilating the unheated areas.
Where attic space is unheated and a stairway is
included, insulation should be used around the stairway
as well as in the first-floor ceiling. The door leading to
the attic should be weather stripped to prevent heat loss.
Walls adjoining an unheated garage or porch should also
be insulated. In structures with flat or low-pitched roofs,
insulation should be used in the ceiling area with
sufficient space allowed above for cleared unobstructed
ventilation between the joists. Insulation should be used
along the perimeter of houses built on slabs. A vapor
barrier should be included under the slab.
In the summer, outside surfaces exposed to the
direct rays of the sun may attain temperatures of 50°F
or more above shade temperatures and tend to transfer
this heat into the house. Insulation in the walls and in
the attic areas retards the flow of heat and improves
summer comfort conditions.
Where air conditioning is used, insulation should be
placed in all exposed ceilings and walls in the same
manner as insulating against cold-weather heat loss.
Shading of glass against direct rays of the sun and the
use of insulated glass helps reduce the air-conditioning
Prior to the actual installation of the
insulation, consult the manufacturer’s specifications and guidelines for personal-protection
items required. Installing insulation is not
particularly hazardous; however, there are
some health safeguards to be observed when
working with fiberglass.
Blanket insulation and batt insulation with a vapor
barrier should be placed between framing members so
that the tabs of the barrier lap the edge of the studs as
well as the top and bottom plates. This method is not
popular with contractors because it is more difficult to
apply the drywall or rock lath (plaster base). However,
it assures a minimum of vapor loss compared to the loss
when the tabs are stapled to the sides of the studs. To
protect the top and soleplates, as well as the headers over
openings, use narrow strips of vapor barrier material
along the top and bottom of the wall (fig. 5-28, view A).
Ordinarily, these areas are not well covered by the vapor
barrier on the blanket or batt. A hand stapler is
commonly used to fasten the insulation and the vapor
barriers in place.
For insulation without a vapor barrier (batt), a
plastic film vapor barrier, such as 4-roil polyethylene, is
commonly used to envelop the entire exposed wall and
ceilings (fig. 5-28, views B and C). It covers the
openings as well as the window and doorheaders and
edge studs. This system is one of the best from the
standpoint of resistance to vapor movement. Furthermore, it does not have the installation inconveniences
encountered when tabs of the insulation are stapled over
Figure 5-28.—Application of insulation.
the edges of the studs. After the drywall is installed or
plastering is completed, the film is trimmed around the
window and door openings.
Reflective insulation, in a single-sheet form with
two reflective surfaces, should be placed to divide the
space formed by the framing members into two
approximately equal spaces. Some reflective insulations
include air spaces and are furnished with nailing tabs.
This type is fastened to the studs to provide at least a
3/4-inch space on each side of the reflective surfaces.
Fill insulation is commonly used in ceiling areas and
is poured or blown into place (fig. 5-28, view C). A vapor
barrier should be used on the warm side (the bottom, in
case of ceiling joists) before insulation is placed. A
leveling board (as shown) gives a constant insulation
thickness. Thick batt insulation might also be combined
to obtain the desired thickness with the vapor barrier
against the back face of the ceiling finish. Ceiling
insulation 6 or more inches thick greatly reduces heat
loss in the winter and also provides summertime
Areas around doorframes and window frames
between the jambs and rough framing members also
require insulation. Carefully fill the areas with
Figure 5-29.—Precautions in insulating.
insulation. Try not to compress the material, which may
cause it to lose some of its insulating qualities. Because
these areas are filled with small sections of insulation, a
vapor barrier must be used around the openings as well
as over the header above the openings (fig. 5-29,
view A). Enveloping the entire wall eliminates the need
for this type of vapor-barrier installation.
In 1 1/2- and 2-story structures and in basements,
the area at the joist header at the outside walls should be
insulated and protected with a vapor barrier (fig. 5-29,
view B). Insulation should be placed behind electrical
outlet boxes and other utility connections in exposed
walls to minimize condensation on cold surfaces.
Most building materials are permeable to water
vapor. This presents problems because considerable
water vapor can be generated inside structures. In cold
climates during cold weather, this vapor may pass
through wall and ceiling materials and condense in the
wall or attic space. In severe cases, it may damage the
exterior paint and interior finish, or even result in
structural member decay. For protection, a material
highly resistive to vapor transmission, called a vapor
barrier, should be used on the warm side of a wall and
below the insulation in an attic space.
Effective vapor-barrier materials include asphalt
laminated papers, aluminum foil, and plastic films. Most
blanket and batt insulations include a vapor barrier on
one side, and some of them with paper-backed aluminum
foil. Foil-backed gypsum lath or gypsum boards are also
available and serve as excellent vapor barriers.
Some types of flexible blanket and batt insulations
have barrier material on one side. Such flexible
insulations should be attached with the tabs at their
sides fastened on the inside (narrow) edges of the studs,
and the blanket should be cut long enough so that the
cover sheet can lap over the face of the soleplate at the
bottom and over the plate at the top of the stud space.
However, such a method of attachment is not the
common practice of most installers.
When a positive seal is desired, wall-height rolls of
plastic-film vapor barriers should be applied over studs,
plates, and window and doorheaders. This system, called
“enveloping,” is used over insulation having no vapor
barrier or to ensure excellent protection when used over
any type of insulation. The barrier should be fitted
tightly around outlet boxes and sealed if necessary. A
ribbon of sealing compound around an outlet or switch
box minimizes vapor loss at this area. Cold-air returns,
located in outside walls, should be made of metal to
prevent vapor loss and subsequent paint problems.
Figure 5-30.—Ice dams and protective ventilation.
paint is quite effective. For rough plasterer for buildings
in very cold climates, two coats of aluminum primer may
be necessary. A pigmented primer and sealer, followed
by decorative finish coats or two coats of rubber-base
paint, are also effective in retarding vapor transmission.
Condensation of moisture vapor may occur in attic
spaces and under flat roofs during cold weather. Even
where vapor barriers are used, some vapor will probably
work into these spaces around pipes and other
inadequately protected areas and through the vapor
barrier itself. Although the amount might be
unimportant if equally distributed, it may be sufficiently
concentrated in some cold spots to cause damage. While
wood shingle and wood shake roofs do not resist vapor
movement, such roofings as asphalt shingles and builtup roofs are highly resistant. The most practical method
of removing the moisture is by adequate ventilation of
roof spaces.
Paint Coatings
Paint coatings cannot substitute for the membrane
types of vapor barriers, but they do provide some
protection for structures where other types of vapor
barriers were not installed during construction. Of the
various types of paint, one coat of aluminum primer
followed by two decorative coats of flat wall oil base
Figure 5-31 .—Attic outlet vents.
A warm attic that is inadequately ventilated and
insulated may cause formation of ice dams at the cornice
(fig. 5-30, view A). During cold weather after a heavy
snowfall, heat causes the snow next to the roof to melt.
Water running down the roof freezes on the colder
surface of the cornice, often forming an ice dam at the
gutter that may cause water to backup at the eaves and
into the wall and ceiling. Similar dams often form in roof
valleys. Ventilation provides part of the solution to these
problems. With a well-insulated ceiling and adequate
ventilation (fig. 5-30 view B), attic temperatures are low
and melting of snow over the attic space greatly reduced.
In hot weather, ventilation of attic and roof spaces
offers an effective means of removing hot air and
lowering the temperature in these spaces. Insulation
should be used between ceiling joists below the attic or
roof space to further retard heat flow into the rooms
below and materially improve comfort conditions.
It is common practice to install louvered openings
in the end walls of gable roofs for ventilation. Air
movement through such openings depends primarily on
wind direction and velocity. No appreciable movement
can be expected when there is no wind. Positive air
movement can be obtained by providing additional
openings (vents) in the soffit areas of the roof overhang
(fig. 5-31, view A) or ridge (view B). Hip-roof
structures are best ventilated by soffit vents and by outlet
ventilators along the ridge. The differences in
temperature between the attic and the outside create an
air movement independent of the wind, and also a more
positive movement when there is wind. Turbine-type
ventilators are also used to vent attic spaces (view C).
Where there is a crawl space under the house or
porch, ventilation is necessary to remove the moisture
vapor rising from the soil. Such vapor may otherwise
condense on the wood below the floor and cause decay.
As mentioned earlier, a permanent vapor barrier on the
soil of the crawl space greatly reduces the amount of
ventilation required.
Tight construction (including storm windows and
storm doors) and the use of humidifiers have created
potential moisture problems that must be resolved by
adequate ventilation and the proper use of vapor
barriers. Blocking of soffit vents with insulation, for
example, must be avoided because this can prevent
proper ventilation of attic spaces. Inadequate ventilation
often leads to moisture problems, resulting in
unnecessary maintenance costs.
Various styles of gable-end ventilators are available.
Many are made with metal louvers and frames, whereas
others may be made of wood to more closely fit the
structural design. However, the most important factors
are to have properly sized ventilators and to locate
ventilators as close to the ridge as possible without
affecting appearance.
Ridge vents require no special framing, only the
disruption of the top course of roofing and the removal
of strips of sheathing. Snap chalk lines running parallel
to the ridge, down at least 2 inches from the peak. Using
a linoleum cutter or a utility knife with a very stiff blade,
cut through the rooting along the lines. Remove the
roofing material and any roofing nails that remain. Set
your power saw to cut through just the sheathing (not
into the rafters) along the same lines. A carbide-tipped
blade is best for this operation. Remove the sheathing.
Nail the ridge vent over the slot you have created, using
gasketed roofing nails. Remember to use compatible
materials. For example, aluminum nails should be used
with aluminum vent material. Because the ridge vent
also covers the top of the roofing, be sure the nails are
long enough to penetrate into the rafters. Caulk the
underside of the vent before nailing.
The openings for louvers and in-the-wall fans
(fig. 5-31, view D) are quite similar. In fact, fans are
usually covered with louvers. Louver slats should have
a downward pitch of 45° to minimize water blowing in.
As with soffit vents, a backing of corrosion-resistant
screen is needed to keep insects out. Ventilation fans
may be manual or thermostatically controlled.
When installing a louver in an existing gable-end
wall, disturb the siding, sheathing, or framing members
Figure 5-32.—Inlet vents.
as little as possible. Locate the opening by drilling small
holes through the wall at each corner Snap chalk lines
to establish the cuts made with a reciprocating saw. Cut
back the siding to the width of the trim housing the
louver (or the louver-with-fan), but cut back the
sheathing only to the dimensions of the fan housing. Box
in the rough opening itself with 2 by 4s and nail or screw
the sheathing to them. Flash and caulk a gable-end
louver as you would a door or a window.
Small, well-distributed vents or continuous slots in
the soffit provide good inlet ventilation. These small
louvered and screened vents (see fig. 5-32, view A) are
easily obtained and simple to install. Only small sections
need to be cut out of the soffit to install these vents,
which can be sawed out before the soffit is installed. It
is better to use several small, well-distributed vents than
a few large ones. Any blocking that might be required
between rafters at the wall line should be installed to
provide an airway into the attic area.
A continuous screened slot vent, which is often
desirable, should be located near the outer edge of the
soffit near the fascia (fig. 5-32, view B). This location
minimizes the chance of snow entering. This type of
vent is also used on the overhang of flat roofs.
This chapter continues our discussion of interior
finishing. In the previous chapter, we looked at the
interior finishing of walls and ceilings, and related
aspects of insulation and ventilation. Now, we’ll
examine the common types of flooring and the
construction procedures for a stairway and interior
doorframing. We’ll also discuss the types of wood trim
and the associated installation procedures.
in bedroom and closet areas where traffic is light.
However, it is less dense than the hardwoods, less wearresistant, and shows surface abrasions more readily.
Softwoods most commonly used for flooring are
southern pine, Douglas fir, redwood, and western
Softwood flooring has tongue-and-groove edges
and may be hollow-backed or grooved. Some types are
also end-matched. Vertical-grain flooring generally has
better wearing qualities than flat-grain flooring under
hard usage.
Hardwoods most commonly used for flooring are
red and white oak, beech, birch, maple, and pecan, any
of which can be prefinished or unfinished.
Hardwood strip flooring is available in widths
ranging from 1 1/2 to 3 1/4 inches. Standard thicknesses
include 3/8, 1/2, and 3/4 inch. A useful feature of
hardwood strip flooring is the undercut. There is a wide
groove on the bottom of each piece that enables it to lay
flat and stable, even when the subfloor surface is slightly
These strips are laid lengthwise in a room and
normally at right angles to the floor joists. A subfloor of
diagonal boards or plywood is normally used under the
finish floor. The strips are tongue and groove and
end-matched (fig. 6-1, view A). Strips are random length
this section, you should be able to identify the
common types of floor coverings and describe
procedures for their placement.
Numerous flooring materials now available may be
used over a variety of floor systems. Each has a property
that adapts it to a particular usage. Of the practical
properties, perhaps durability and ease of maintenance
are the most important. However, initial cost, comfort,
and appearance must also be considered. Specific
service requirements may call for special properties,
such as resistance to hard wear in warehouses and on
loading platforms, or comfort to users in offices and
There is a wide selection of wood materials used for
flooring. Hardwoods and softwoods are available as
strip flooring in a variety of widths and thicknesses, and
as random-width planks and block flooring. Other
materials include linoleum, asphalt, rubber, cork vinyl,
and tile and sheet forms. Tile flooring is also available
in a particleboard, which is manufactured with small
wood particles combined with resin and formed under
high pressure. In many areas, ceramic tile and carpeting
are used in ways not thought practical a few years ago.
Plastic floor coverings used over concrete or a stable
wood subfloor are another variation in the types of
finishes available.
Softwood finish flooring costs less than most
hardwood species and is often used to good advantage
Figure 6-1.—Types of strip flooring.
and may vary from 2 to more than 16 feet. The top is
slightly wider than the bottom so that tight joints result
when flooring is laid. The tongue fits tightly into the
groove to prevent movement and floor squeaks.
Thin strip flooring (fig. 6-1. view B) is made of 3/8by 2-inch strips. This flooring is commonly used for
remodeling work or when the subfloor is edge-blocked
or thick enough to provide very little deflection under
Square-edged strip flooring (fig. 6-1, view C) is
also occasionally used. The strips are usually 3/8 inch
by 2 inches and laid over a substantial subfloor.
Face-nailing is required for this type of flooring.
Plank floors are usually laid in random widths. The
pieces are bored and plugged to simulate wooden pegs
originally used to fasten them in place. Today, this type
of floor has tongue-and-groove edges. It is laid similar
to regular strip flooring. Solid planks are usually
3/4 inch thick. Widths range from 3 to 9 inches in
multiples of 1 inch.
Figure 6-2.—Application of strip flooring.
Flooring should be laid after drywall, plastering, or
other interior wall and ceiling finish is completed and
dried out. Windows and exterior doors should be in
place, and most of the interior trim, except base, casing,
and jambs, should be installed to prevent damage by
wetting or construction activity.
Board subfloors should be clean and level and
covered with felt or heavy building paper. The felt or
paper stops a certain amount of dust, somewhat deadens
sound, and, where a crawl space is used, increases the
warmth of the floor by preventing air infiltration. As a
guide to provide nailing into the joists, wherever
possible, mark with a chalk line the location of the joists
on the paper. Plywood subflooring does not normally
require building paper.
Strip flooring should normally be laid crosswise to
the floor joists (fig. 6-2, view A). In conventional
structures, the floor joists span the width of the building
over a center-supporting beam or wall. Thus, the finish
flooring of the entire floor areas of a rectangular
structure will be laid in the same direction. Flooring with
“L”- or “I’’-shaped plans will usually have a direction
change, depending on joist direction. As joists usually
span the short way in a room, the flooring will be laid
lengthwise to the room. This layout has a pleasing
appearance and also reduces shrinkage and swelling of
the flooring during seasonal changes.
When the flooring is delivered, store it in the
warmest and driest place available in the building.
Moisture absorbed after delivery to the building site is
the most common cause of open joints between flooring
strips that appear after several months of the heating
Floor Squeaks
Floor squeaks are usually caused by the movement
of one board against another. Such movement can occur
for a number of reasons: floor joists too light, causing
excessive deflection; sleepers over concrete slabs not
held down tightly; loose fitting tongues; or poor nailing.
Adequate nailing is an important means of minimizing
squeaks. Another is to apply the finish floors only after
the joists have dried to 12-percent moisture content or
less. A much better job results when it is possible to nail
through the finish floor, through the subfloor, and into
the joists than if the finish floor is nailed only to the
Various types of nails are used in nailing different
thicknesses of flooring. Before using any type of nail,
you should check with the floor manufacturer’s
Figure 6-4.—Floor detail for existing concrete construction.
Figure 6-3.—Nailing wood flooring.
recommendations as to size and diameter for specific
uses. Flooring brads are also available with blunted
points to prevent splitting the tongue.
Figure 6-2, view B, shows how to nail the first strip
of flooring. This strip should be placed 1/2 to 5/8 inch
away from the wall. The space is to allow for expansion
of the flooring when moisture content increases. The
first nails should be driven straight down, through the
board at the groove edge. The nails should be driven
into the joist and near enough to the edge so that they
will be covered by the base or shoe molding. The first
strip of flooring can also be nailed through the tongue
(fig, 6-3, view A). This figure shows in detail how nails
should be driven into the tongue of the flooring at an
angle of 45° to 50°. Don’t drive the nails flush; this
prevents damaging the edge by the hammerhead
(fig. 6-3 view B). These nails should be set with a nail
To prevent splitting the flooring, predrill through the
tongue, especially at the ends of the strip. For the second
course of flooring from the wall, select pieces so that the
butt joints are well separated from those in the first
course. Under normal conditions, each board should be
driven up tightly against the previous board. Cracked
pieces may require wedging to force them into alignment or may be cut and used at the ends of the course
or in closets. In completing the flooring, you should
provide a 1/2- to 5/8-inch space between the wall and
the last flooring strip. This strip should be face-nailed
Figure 6-5.—Base for wood flooring on a slab with vapor barrier.
just like the first strip so that the base or shoe covers the
set nailheads (fig. 6-2, view B).
Installation over Concrete
One of the most critical factors in applying wood
flooring over concrete is the use of a good vapor barrier
under the slab to resist ground moisture. The vapor
barrier should be placed under the slab during
construction. However, an alternate method must be
used when the concrete is already in place (shown in
fig. 6-4).
A system of preparing a base for wood flooring
when there is a vapor barrier under the slab is shown in
figure 6-5. Treated 1-by 4-inch furring strips should be
of flooring, held together with glue, metal splines, or
other fasteners. Square and rectangular units are
produced. Generally, each block is laid with its grain at
right angles to the surrounding units.
Blocks, called laminated units, are produced by
gluing together several layers of wood. Unit blocks are
commonly produced in 3/4-inch thicknesses. Dimensions (length and width) are in multiples of the widths
of the strips from which they are made. For example,
squares assembled from 2 1/4-inch strips are 6 3/4 by
6 3/4 inches, 9 by 9 inches, or 11 1/4 by 11 1/4 inches.
Wood block flooring is usually tongue and groove.
Flooring materials, such as asphalt, vinyl, linoleum,
and rubber, usually reveal rough or irregular surfaces in
the flooring structure upon which they are laid.
Conventional subflooring does not provide a
satisfactory surface. An underpayment of plywood or
hardboard is required. On concrete floors, a special
mastic material is sometimes used when the existing
surface is not suitable as a base for the finish flooring.
An underpayment also prevents the finish flooring
materials from checking or cracking when slight
movements take place in a wood subfloor. When used
for carpeting and resilient materials, the underpayment
is usually installed as soon as wall and ceiling surfaces
are complete.
Figure 6-6.—Wind block (parquet) laminated flooring.
anchored to the existing slab. Shims can be used, when
necessary, to provide a level base. Strips should be
spaced no more than 16 inches on center (OC). A good
waterproof or water-vapor resistant coating on the
concrete before the treated strips are installed is usually
recommended to aid in further reducing moisture
movement. A vapor barrier, such as a 4-mil polyethylene
or similar membrane, is then laid over the anchored
1- by 4-inch wood strips and a second set of 1 by 4s
nailed to the first. Use 1 1/2-inch-long nails spaced 12
to 16 inches apart in a staggered pattern. The moisture
content of these second members should be
approximately the same as that of the strip flooring to
be applied. Strip flooring can then be installed as
previously described.
When other types of finish floor, such as a resilient
tile, are used, plywood underpayment is placed over the
1 by 4s as a base.
Hardboard and Particleboard
Hardboard and particleboard both meet the
requirements of an underpayment board. The standard
thickness for hardboard is 1/4 inch. Particleboard
thicknesses range from 1/4 to 3/4 inch.
This type of underpayment material will bridge
small cups, gaps, and cracks. Larger irregularities
should be repaired before the underlayment is applied.
High spots should be sanded down and low areas filled.
Panels should be unwrapped and placed separately
around the room for at least 24 hours before they are
installed. This equalizes the moisture content of the
panels before they are installed.
INSTALLATION.— To install hardboard or particleboard, start atone corner and fasten each panel securely
before laying the next. Some manufacturers print a
nailing pattern on the face of the panel. Allow at least a
1/8- to 3/8-inch space next to a wall or any other vertical
surface for panel expansion.
Stagger the joints of the underpayment panel. The
direction of the continuous joints should be at right
Wood block (parquet) flooring (fig. 6-6) is used to
produce a variety of elaborate designs formed by small
wood block units. A block unit consists of short lengths
To install plywood underpayment, follow the same
general procedures described for hardboard. Turn the
grain of the face-ply at right angles to the framing
supports. Stagger the end joints. Nails may be spaced
farther apart for plywood but should not exceed a field
spacing of 10 inches (8 inches for 1/4- and 3/8-inch
thicknesses) and an edge spacing of 6 inches OC. You
should use ring-grooved or cement-coated nails to
install plywood underpayment.
Figure 6-7.—Fasteners for underpayment.
After the underpayment is securely fastened, sweep
and vacuum the surface carefully. Check to see that
surfaces are smooth and joints level. Rough edges
should be removed with sandpaper or a block plane.
The smoothness of the surface is extremely
important, especially under the more pliable materials
(vinyl, rubber, linoleum). Over a period of time, these
materials will “telegraph” (show on the surface) even
the slightest irregularities or rough surfaces. Linoleum
is especially susceptible. For this reason, a base layer of
felt is often applied over the underpayment when
linoleum, either in tile or sheet form, is installed.
Because of the many resilient flooring materials on
the market, it is essential that each application be made
according to the recommendations and instructions
furnished by the manufacturer of the product.
Figure 6-8.—A1ignment of finish flooring materials.
angles to those in the subfloor. Be especially careful to
avoid aligning any joints in the underpayment with those
in the subfloor. Leave a 1/32-inch space at the joints
between hardboard panels. Particleboard panels should
be butted lightly.
Installing Resilient Tile
Start a floor tile layout by locating the center of the
end walls of the room. Disregard any breaks or
irregularities in the contour. Establish a main centerline
by snapping a chalk line between these two points.
When snapping long lines, remember to hold the line at
various intervals and snap only short sections.
Next, lay out another center line at right angles to
the main center line. This line should be established by
using a framing square or set up a right triangle (fig. 6-9)
FASTENERS.— Underlayment panels should be
attached to the subfloor with approved fasteners.
Examples are shown in figure 6-7. For hardboard, space
the fasteners 3/8 inch from the edge.
Spacing for particleboard varies for different
thicknesses. Be sure to drive nailheads flush. When
fastening underpayment with staples, use a type that is
etched or galvanized and at least 7/8 inch long. Staples
should not be spaced over 4 inches apart along panel
Special adhesives can also be used to bond underpayment to subfloors. They eliminate the possibility of
nail-popping under resilient floors.
Plywood is preferred by many for underpayment. It
is dimensionally stable, and spacing between joints is
not critical. Since a range of thicknesses is available,
alignment of the surfaces of various finish flooring
materials is easy. An example of aligning resilient
flooring with wood strip flooring is shown in figure 6-8.
Figure 6-9.—Establishing center for laying floor tile.
with length 3 feet, height 4 feet, and hypotenuse 5 feet.
In a large room, a 6:8: 10-foot triangle can be used. To
establish this triangle, you can either use a chalk line or
draw the line along a straightedge.
With the centerlines established, make a trial layout
of tile along the center lines. Measure the distance
between the wall and last tile. If the distance is less than
2 inches or more than 8 inches, move the centerline half
the width of the tile (4 1/2 inches for a 9 by 9 tile) closer
to the wall. This adjustment eliminates the need to install
border tiles that are too narrow. (As you will learn
shortly, border tiles are installed as a separate
operation-after the main area has been tiled.) Check
the layout along the other center line in the same way.
Since the original center line is moved exactly half the
tile size, the border tile will remain uniform on opposite
sides of the room. After establishing the layout, you are
now ready to spread the adhesive.
Figure 6-10.—Layout of a border tile.
Allow the adhesive to take an initial set before a
single tile is laid. The time required will vary from a
minimum of 15 minutes to a much longer time,
depending on the type of adhesive used. Test the surface
with your thumb. It should feel slightly tacky but should
not stick to your thumb.
SPREADING ADHESIVE.— Before you spread
the adhesive, reclean the floor surface. Using a notched
trowel, spread the adhesive over one-quarter of the total
area bringing the spread up to the chalk line but not
covering it. Be sure the depth of the adhesive is the depth
recommended by the manufacturer.
LAYING THE TILE.— Start laying the tile at the
center of the room. Make sure the edges of the tile align
with the chalk line. If the chalk line is partially covered
with the adhesive, snap a new one or tack down a thin,
straight strip of wood to act as a guide in placing the tile.
The spread of adhesive is very important. If it is too
thin, the tile will not adhere properly. If too heavy, the
adhesive will bleed between the joints.
Table 6-1.—Estimating Adhesive for Floor Tile
Table 6-2.—Estimating Floor Tile
Butt each tile squarely to the adjoining tile, with the
comers in line. Carefully lay each tile in place. Do not
slide the tile; this causes the adhesive to work up
between the joints and prevents a tight fit. Take
sufficient time to position each tile correctly. There is
usually no hurry since most adhesives can be “worked’
over a period of several hours.
To remove air bubbles, rubber, vinyl, and linoleum
are usually rolled after a section of the floor is laid. Be
sure to follow the manufacturer’s recommendations.
Asphalt tile does not need to be rolled.
After the main area is complete, set the border tile
as a separate operation. To lay out a border tile, place a
loose tile (the one that will be cut and used) over the last
tile in the outside row. Now, take another tile and place
it in position against the wall and mark a sharp pencil
line on the first tile (fig. 6-10).
Cut the tile along the marked line, using heavy-duty
shears or tin snips. Some types of tile require a special
cutter or they may be scribed and broken. Asphalt tile,
if heated, can be easily cut with snips.
Afler all sections of the floor have been completed,
install the cove along the wall and around fixtures. A
special adhesive is available for this operation. Cut the
proper lengths and make a trial fit. Apply the adhesive
to the cove base and press it into place.
Check the completed installation carefully. Remove
any spots of adhesive. Work carefully using cleaners and
procedures approved by the manufacturer.
SELF-ADHERING TILE.— Before installing
self-adhering tile, you must first ensure that the floors
are dry, smooth, and completely free of wax, grease, and
dirt. Generally, tiles can be laid over smooth-faced
resilient floors. Embossed floors, urethane floors, or
cushioned floors should be removed.
Self-adhering tile is installed in basically the same
way as previously mentioned types of tile. Remove the
paper from the back of the tile, place the tile in position
on the floor, and press it down.
Estimating Floor Tile Materials
to find the number of tiles needed, then add the waste
Use table 6-1 when estimating resilient floor tile
materials. This table gives you approximate square feet
coverage per gallon of different types of primer and
adhesives. Be sure to read and follow the manufacturer’s
directions. Table 6-2 provides figures for estimating the
two sizes of tile most commonly used. After calculating
the square feet of the area to be tiled, refer to the table
To find the number of tiles required for an area not
shown in this table, such as the number of 9- by 9-inch
tiles required for an area of 550 square feet, add the
number of tiles needed for 50 square feet to the number
of tile needed for 500 square feet. The result will be 979
tiles, to which you must add 5 percent for waste. The
total number of tiles required is 1,028.
longest points. This will result in some waste material,
but is safer than ordering less than what you need.
When tiling large areas, work from several different
boxes of tile. This will avoid concentrating one color
shade variation in one area of the floor.
Most wall-to-wall carpeting is priced by the square
yard. To determine how many square yards you need,
multiply the length by the width of the room in feet and
divide the result by 9.
Because of its flexibility, vinyl flooring is very easy
to install. Since sheets are available in 6- to 12-foot
widths, many installations can be made free of seams.
Flexible vinyl flooring is fastened down only around the
edges and at seams. It can be installed over concrete,
plywood, or old linoleum.
Except for so-called “one-piece” and cushionbacked carpeting, underpayment or padding is essential
to a good carpet installation. It prolongs the life of the
carpeting, increases its soundproofing qualities, and
adds to underfoot comfort.
To install, spread the sheet smoothly over the floor.
Let excess material turn up around the edges of the
room. Where there are seams, carefully match the
pattern. Fasten the two sections to the floor with
adhesive. Trim the edges to size by creasing the vinyl
sheet material at intersections of the floor and walls and
cutting it with a utility knife drawn along a straightedge.
Be sure the straightedge is parallel to the wall.
The most common types of carpet padding are latex
(rubber), sponge-rubber foams, soft-and-hardback vinyl
foams, and felted cushions made of animal hair or of a
combination of hair and jute. Of all types, the latex and
vinyl foams are generally considered the most practical.
Their waffled surface tends to hold the carpet in place.
Most carpet padding comes in a standard 4 1/2-foot
After the edges are trimmed and fitted, secure them
with a staple gun, or use a band of double-faced adhesive
tape. Always study the manufacturer’s directions
carefully before starting the work.
Wall-to-wall carpeting can make a small room look
larger, insulate against drafty floors, and do a certain
amount of soundproofing. Carpeting is not difficult to
Cushion-backed carpeting is increasing in popularity, especially with do-it-yourself homeowners. The
high-density latex backing is permanently fastened to
the carpet, which eliminates the need for a separate
underpadding. It is nonskid and heavy enough to hold
the carpet in place without the use of tacks. In addition,
the foam rubber backing keeps the edges of the carpet
from unraveling so that it need not be bound. Foam
rubber is mildewproof and unaffected by water, so the
carpet can be used in basements and other below-grade
installations. It can even be laid directly over unfinished
All carpets consist of a surface pile and backing. The
surface pile may be nylon, polyester, polypropylene,
acrylic, wool, or cotton. Each has its advantages and
disadvantages. The type you select depends on your
needs. Carpeting can be purchased in 9-, 12-, and
15-foot widths.
The key feature of this backing, however, is the
dimensional stability it imparts to the carpet. This added
characteristic means the carpet will not stretch, nor will
it expand and contract from temperature or humidity
changes. Because of this, these carpets can be loose-laid,
with no need for adhesive or tacks to give them stability.
Measuring and Estimating
Preparing the Floor
Measure the room in the direction in which the
carpet will be hid. To broaden long, narrow rooms, lay
patterned or striped carpeting across the width. For
conventional y rectangular rooms, measure the room
lengthwise. Include the full width of doorframes so the
carpet will extend slightly into the adjoining room.
When measuring a room with alcoves or numerous wall
projections, calculate on the basis of the widest and
To lay carpets successfully on wood floors, you
must ensure that the surface is free of warps, and that all
nails and tacks are either removed or hammered flush.
Nail down any loose floorboards and plane down the
ridges of warped boards. Fill wide cracks between
floorboards with strips of wood or wood putty. Cover
floors that are warped and cracked beyond reasonable
repair with hardboard or plywood.
batten with a number of spikes projecting at a 60° angle.
The battens are nailed to the floor around the entire
room, end to end and 1/4 inch from the baseboard, with
the spikes facing toward the wall. The spikes grip the
backing of the carpet to hold it in place. On stone or
concrete floors, the battens are glued in place with
special adhesives.
Though cushion-backed carpeting can stay in place
without fastening, securing with double-face tape is the
preferred method. Carpets can also be attached to the
floor with Velcro™ tape where the frequent
removability of the carpet for cleaning and maintenance
is a factor.
Carpet Installation
To install a carpet, you will need a hammer, large
scissors, a sharp knife, a 3-foot rule, needle and carpet
thread, chalk and chalk line, latex adhesive, and carpet
tape. The only specialized tool you will need is a carpet
stretcher, often called a knee-kicker.
Before starting the job, remove all furniture and any
doors that swing into the room. When cutting the carpet,
spread it out on a suitable floor space and chalk the exact
pattern of the room on the pile surface; then cut along
the chalk line with the scissors or sharp knife.
Join unseamed carpet by placing the two pieces so
the pile surfaces meet edge to edge. Match patterned
carpets carefully. With plain carpets, lay each piece so
the piles run the same way. Join the pieces with carpet
thread, taking stitches at 18-inch intervals along the
seam. Pull the carpet tight after each stitch to take up
slack. Sew along the seam between stitches. Tuck any
protruding fibers back into the pile. Carpet can also be
seamed by cementing carpet tape to the backing threads
with latex adhesive.
Open the carpet to room length and position it
before starting to putdown the padding. The pile should
fall away from windows to avoid uneven shading in
daylight. Fold one end of the carpet back halfway and
put the padding down on the exposed part of the floor.
Do the same at the other end. This avoids wrinkles
caused by movement of the padding.
To tack start at the corner of the room that is formed
by the two walls with the fewest obstructions. Butt the
carpet up against the wall, leaving about 1 1/2 inches up
the baseboard for hemming. Attach the carpet
temporarily with tacks about 6 inches from the
baseboard along these two walls. Use the knee-kicker to
stretch the carpet, first along the length, then the width,
Start from the middle of the wall, stretching alternately
toward opposite comers. When it is smooth, tack down
the stretched area temporarily.
Figure 6-11.—Carpet installation.
Stone or concrete floors that have surface ridges or
cracks should be treated beforehand with a
floor-leveling compound to reduce carpet wear. These
liquid compounds are also useful for sealing the surface
of dusty or powdery floors. A thin layer of the
compound, which is floated over the floor, will keep dust
from working its way up through the underpayment and
into the carpet pile.
The best carpeting for concrete and hard tile
surfaces is the indoor-outdoor type. The backing of this
carpet is made of a closed-pore type of either latex or
vinyl foam, which keeps out most moisture. It is not wise
to lay any of the standard paddings on top of floor tiles
unless the room is well ventilated and free of
condensation. Vinyl and asbestos floor tiles accumulate
moisture when carpeting is laid over them. This
condensation soaks through into the carpet and
eventually causes a musty odor. It can also produce
mildew stains.
Fastening Carpets
The standard fastening methods are with tacks or by
means of tackless fittings. Carpets can also be loose-hid
with only a few tacks at entrances. Carpet tack lengths
are 3/4 and 1 inch. The first is long enough to go through
a folded carpet hem and anchor it firmly to the floor (fig.
6-11, view A). The 1-inch tacks are used in corners
where the folds of the hem make three thicknesses.
Tackless fittings (fig. 6-11, view B) are a convenient
fastening method. They consist of a 4-foot wooden
Figure 6-12.—Carpet installation using tackless fastenings.
to prevent fraying if the salvage has been trimmed off.
Cement carpet tape to the backing threads with latex
adhesive. Nonwoven or latex-backed carpet will not
fray, but tape is still advisable to protect exposed edges.
Any door that drags should be removed and trimmed.
When installing cushion-backed carpeting, you cart
Cut slots for pipes, fireplace protrusions, and
radiators. Trim back the padding to about 2 inches from
the wall to leave a channel for the carpet hem. Fold the
hem under and tack the carpet in place with a tack every
5 inches. Be sure the tacks go through the fold
When installing carpet, use tackless fastening strips,
as shown in figure 6-12, view A. Position and trim the
padding (view B) so that it meets the strip at the wall,
but does not overlap the strip. Tack it down so it does
not move. Lay out the carpeting and, using a
knee-kicker, stretch the carpet over the nails projecting
out of the tackless strip (view C). Trim the carpet,
leaving a 3/8-inch overlap, which is tucked into place
between the wall and the tackless strip (view D). (If you
trim too much carpeting, lift the carpeting off the spikes
of the tackless strip and use the knee-kicker to restretch
the carpet [view E]). Protect the exposed edge of the
carpet at doorways with a special metal binder strip or
bar (view F). The strip is nailed to the floor at the
doorway and the carpet slipped under a metal lip, which
is then hammered down to grip the carpet edge.
Tacks can be used as an alternative to a binder strip.
Before tacking, tape the exposed edge of woven carpet
eliminate several steps. For instance, you don’t need to
use tack strips or a separate padding. Although these
instructions apply to most such carpeting, read the
manufacturer’s instructions for any deviation in
technique or use of material.
To install a cushioned carpet, apply 2-inch-wide
double-face tape flush with the wall around the entire
room (fig. 6-13, view A). Roll out and place the carpet.
Fold back the carpet and remove the protective paper
from the tape. Press the carpet down firmly over the tape
and trim away excess (view B). A metal binder strip or
an aluminum saddle is generally installed in doorways
(view C). If your room is wider than the carpet, you will
have to seam two pieces together. Follow the
manufacturer’s recommendations.
Figure 6-13.—Installing cushion-backed carpeting.
Figure 6-14.—Stairways.
another. All stairs have two main parts, called treads and
stringers. The underside of a simple stairway, consisting
only of stringers and treads, is shown in figure 6-14,
view A. Treads of the type shown are called plank treads.
This simple type of stairway is called a cleat stairway
because of the cleats attached to the stringers to support
the treads.
A more finished type of stairway has the treads
mounted on two or more sawtooth-edged stringers, and
includes risers (fig. 6-14, view B). The stringers shown
this section, you should be able to describe a
stairway layout and how to frame stairs
according to drawings and specifications.
There are many different kinds of stairs (interior and
exterior), each serving the same purpose—the
movement of personnel and products from one floor to
surface to the upper subfloor surface will be the same as
the eventual distance between the finish floor surfaces.
The distance is, therefore, equal to the total rise of the
stairway. But if you are measuring up from a finish floor,
such as a concrete basement floor, then you must add to
the measured distance the thickness of the upper finish
flooring to get the total rise of the stairway. If the upper
and lower finish floors will be of different thickness,
then you must add the difference in thickness to the
measured distance between subfloor surfaces to get the
rise of the stairway. To measure the vertical distance, use
a straight piece of lumber plumbed in the stair opening
with a spirit level.
Let’s assume that the total rise measures 8 feet
11 inches, as shown in figure 6-15. Knowing this, you
can determine the unit rise as follows. First, reduce the
total rise to inches-in this case it comes to 107 inches.
Next, divide the total rise in inches by the average unit
rise, which is 7 inches. The result, disregarding any
fraction, is the number of risers the stairway will
have—in this case, 107/7 or 15. Now, divide the total
rise in inches by the number of risers-in this case,
107/15, or nearly 7 1/8 inches. This is the unit rise, as
shown in figure 6-15.
Figure 6-15.—Unit rise and run.
are cut from solid pieces of dimensional lumber (usually
2 by 12s) and are called cutout, or sawed, stringers.
The first step in stairway layout is to determine the
unit rise and unit run (fig. 6-14, view B). The unit rise
is calculated on the basis of the total rise of the stairway,
and the fact that the customary unit rise for stairs is
7 inches.
The unit run is calculated on the basis of the unit
rise and a general architect’s rule that the sum of the unit
run and unit rise should be 17 1/2 inches. Then, by this
rule, the unit run is 17 1/2 inches minus 7 1/8 inches or
10 3/8 inches.
The total rise is the vertical distance between the
lower finish-floor level and the upper finish-floor level.
This may be shown in the elevations. However, since
the actual vertical distance as constructed may vary
slightly from that shown in the plans, the distance should
be measured.
You can now calculate the total run of the stairway.
The total run is the unit run multiplied by the total
number of treads in the stairway. However, the total
number of treads depends upon the manner in which the
upper end of the stairway will be anchored to the header.
At the time stairs are laid out, only the subflooring
is installed. If both the lower and the upper floors are to
be covered with finish flooring of the same thickness,
the measured vertical distance from the lower subfloor
In figure 6-16, three methods of anchoring the upper
end of a stairway are shown. In view A, there is a
complete tread at the top of the stairway. This means the
number of complete treads is the same as the number of
Figure 6.16.—Method for anchoring upper end of a stairway.
Figure 6-17.—Layout of lower end of cutout stringer.
risers. For the stairway shown in figure 6-15, there are
15 risers and 15 complete treads. Therefore, the total run
of the stairway is equal to the unit run times 15, or 12 feet
11 5/8 inches.
stairway has a total rise of 8 feet 11 inches and a total
run of 12 feet 11 5/8 inches. The stringer must be long
enough to form the hypotenuse of a triangle with sides
of those two lengths. For an approximate length
estimate, call the sides 9 and 13 feet long. Then, the
length of the hypotenuse will equal the square root of 9 2
plus 132. This is the square root of 250, about 15.8 feet
or 15 feet 9 1/2 inches.
In view B, only part of a tread is at the top of the
stairway. If this method were used for the stairway
shown in figure 6-15, the number of complete treads
would be one less than the number of risers, or 14, The
total run of the stairway would be the product of 14
multiplied by 10 3/8, plus the run of the partial tread at
the top. Where this run is 7 inches, for example, the total
run equals 152 1/4 inches, or 12 feet 8 1/4 inches.
Extreme accuracy is required in laying out the
stringers. Be sure to use a sharp pencil or awl and make
the lines meet on the edge of the stringer material.
Figure 6-17 shows the layout at the lower end of the
stringer. Set the framing square to the unit run on the
tongue and the unit rise on the blade, and draw the line
AB. This line represents the bottom tread. Then, draw
AD perpendicular to AB. Its length should be equal to
the unit rise. This line represents the bottom riser in the
stairway. You may have noticed that the thickness of a
tread in the stairway has been ignored. This thickness is
now about to be accounted for by making an allowance
in the height of this first riser. This process is called
“dropping the stringer.”
In view C, there is no tread at all at the top of the
stairway. The upper finish flooring serves as the top
tread. In this case, the total number of complete treads
is again 14, but since there is no additional partial tread,
the total run of the stairway is 14 times 10 3/8 inches, or
145 1/4 inches, or 12 feet 1 1/4 inches.
When you have calculated the total run of the
stairway, drop a plumb bob from the header to the floor
below and measure off the total run from the plumb bob.
This locates the anchoring point for the lower end of the
As you can see in figure 6-14, view B, the unit rise
is measured from the top of one tread to the top of the
next for all risers except the bottom one. For the bottom
riser, unit rise is measured from the finished floor
surface to the surface of the first tread. If AD were cut
to the unit rise, the actual rise of the first step would be
the sum of the unit rise plus the thickness of a tread.
Therefore, the length of AD is shortened by the
thickness of a tread, as shown in figure 6-17, by the
As mentioned earlier, cutout stringers for main
stairways are usually made from 2 by 12 stock Before
cutting the stringer, you will first need to solve for the
length of stock you need.
Assume that you are to use the method of upper-end
anchorage shown in view A of figure 6-16 to lay out a
stringer for the stairway shown in figure 6-15. This
Figure 6-18.—Layout of upper end of cutout stringer.
Figure 6-19.—Kickplate for anchoring stairs to concrete.
thickness of a tread less the thickness of the finish
flooring. The first is done if the stringer rests on a finish
floor, such as a concrete basement floor. The second is
done where the stringer rests on subflooring.
When you have shortened AD to AE, draw EF
parallel to AB. This line represents the bottom horizontal
anchor edge of the stringer. Then, proceed to lay off the
remaining risers and treads to the unit rise and unit
run until you have laid off 15 risers and 15 treads.
Figure 6-18 shows the layout at the upper end of the
stringer. The line AB represents the top, the 15th tread.
BC, drawn perpendicular to AB, represents the upper
vertical anchor edge of the stringer. This edge butts
against the stairwell header.
In a given run of stairs, be sure to make all the risers
the same height and treads the same width. An unequal
riser, especially one that is too high, is dangerous.
Figure 6-20.—Finish stringer.
We have been dealing with a common straight-flight
stairway—meaning one which follows the same
direction throughout. When floor space is not extensive
enough to permit construction of a straight-flight
stairway, a change stairway is installed-meaning one
which changes direction one or more times. The most
common types of these are a 90° change and a 180°
change. These are usually platform stairways,
successive straight-flight lengths, connecting platforms
at which the direction changes 90° or doubles back 180°.
Such a stairway is laid out simply as a succession of
straight-flight stairways.
on cutout stringers or stair-block stringers, but no risers.
The lower ends of the stringers on porch, basement, and
other stairs anchored on concrete are fastened with a
kickplate (shown in fig. 6-19).
When dealing with stairs, it is vitally important to
remember the allowable head room. Head room is
defined as the minimum vertical clearance required
from any tread on the stairway to any part of the ceiling
structure above the stairway. In most areas, the local
building codes specify a height of 6 feet 8 inches for
main stairs, and 6 feet 4 inches for basement stairs.
The stairs in a structure are broadly divided into
principal stairs and service stairs. Service stairs are
porch, basement, and attic stairs. Some of these maybe
simple cleat stairways; others may be open-riser
stairways. An open-riser stairway has treads anchored
A principal stairway usually has a finished
appearance. Rough cutout stringers are concealed by
Treads and risers should be nailed to stringers with
6d, 8d, or 10d finish nails, depending on the thickness
of the stock,
this section, you should be able to describe the
procedures for laying out and installing
interior dooframes, doors, and the hardware
Figure 6-21.—Rabbet-and-groove-jointed treads and risers.
Rough openings for interior doors are usually
framed to be 3 inches higher than the door height and
2 1/2 inches wider than the door width. This provides
for the frame and its plumbing and leveling in the
opening. Interior doorframes are made up of two side
jambs, a head jamb, and the stop moldings upon which
the door closes. The most common of these jambs is the
one-piece type (shown in fig. 6-23, view A). Jambs can
be obtained in standard 5 1/4 inch widths for plaster
walls and 4 5/8 inch widths for walls with 1/2-inch
drywall finish. The two- and three-piece adjustable
jambs (views B and C) are also standard types. Their
principal advantage is in being adaptable to a variety of
wall thicknesses.
Some manufacturers produce interior doorframes
with the doors fitted and prehung, ready for installing.
Installation of the casing completes the job. When used
with two- or three-piece jambs, casings can even be
installed at the factory.
Figure 6-22.—Joining a baluster to the tread.
finish stringers (see fig. 6-20). Treads and risers are
often rabbet-jointed as in figure 6-21.
Vertical members that support a stairway handrail
are called balusters. Figure 6-22 shows a method of
joining balusters to treads. Here, dowels, shaped on the
lower ends of the balusters, are glued into holes bored
in the treads.
Stringers should be toenailed to stairwell double
headers with 10d nails, three to each side of the stringer.
Those which face against trimmer joists should each be
nailed to the joists with at least three 16d nails. At the
bottom, a stringer should be toenailed with 10d nails,
four to each side, driven into the subflooring and, if
Figure 6-23.—Interior door framing parts.
possible, into a joist below.
Figure 6-25.-Interior door types.
doors (fig. 6-25, view A) maybe obtained in gum, birch,
oak mahogany, and several other wood species, most of
which are suitable for natural finish. Nonselected grades
are usually painted as hardboard-faced doors.
Figure 6-24.—Hollow-core construction of flushed doors.
The panel door consists of solid stiles (vertical side
members), rails (cross pieces), and panels of various
types. The five-cross panel and the colonial-type panel
doors are perhaps the most common of this style
(fig. 6-25, views B and C). The louvered door (view D)
is also popular and is commonly used for closets because
it provides some ventilation. Large openings for
wardrobes are finished with sliding or folding doors, or
with flush or louvered doors (view E). Such doors are
usually 1 1/8 inches thick.
Common minimum widths for single interior doors
are as follows: bedrooms and other habitable rooms,
2 feet 6 inches; bathrooms, 2 feet 4 inches; and small
closets and linen closets, 2 feet. These sizes vary a great
deal, and sliding doors, folding door units, and similar
types are often used for wardrobes and may be 6 feet or
more in width. However, in most cases, the jamb stop
and casing parts are used in some manner to frame and
finish the opening.
Hinged doors should open or swing in the direction
of natural entry, against a blank wall whenever possible.
They should not be obstructed by other swinging doors.
Doors should never be hinged to swing into a hallway.
Casing is the edge trim around interior door
openings and is also used to finish the room side of
windows and exterior doorframes. Casing usually varies
in widths from 2 1/4 to 3 1/2 inches, depending on the
style. Casing is available in thicknesses from 1/2 to
3/4 inch, although 11/1 6 inch is standard in many of the
narrow-line patterns. A common casing pattern is shown
in figure 6-23, view D.
When the frame and doors are not assembled and
prefitted, the side jambs should be fabricated by nailing
through the dado into the head jamb with three 7d or 8d
coated nails (fig. 6-23 view A). The assembled frames
are then fastened in the rough openings by shingle
wedges used between the side jamb and the stud (fig.
6-26, view A). One jamb is plumbed and leveled using
four or five sets of shingle wedges for the height of the
frame. Two 8d finishing nails should be used at each
The two general types of interior doors are the flush
and the panel. Flush interior doors usually have a hollow
core of light framework and are faced with thin plywood
or hardboard (shown in fig. 6-24). Plywood-faced flush
Figure 6-26.—Doorframe and trim.
casing is square-edged, a butt joint maybe made at the
junction of the side and head casing (fig. 6-26, view C),
If the moisture content of the casing material is high, a
mitered joint may open slightly at the outer edge as the
material dries. This can be minimized by using a small
glued spline at the corner of the mitered joint. Actually,
use of a spline joint under any moisture condition is
considered good practice, and some prefitted jamb,
door, and casing units are provided with splined joints.
Nailing into the joint after drilling helps retain a close
wedged area one driven so that the doorstop covers it.
The opposite side jamb is then fastened in place with
shingle wedges and finishing nails, using the first jamb
as a guide in keeping a uniform width.
Casings should be nailed to both the jamb and the
framing members. You should allow about a 3/16-inch
edge distance from the face of the jamb. Use 6d or 7d
finish or casing nails, depending on the thickness of the
casing. To nail into the stud, use 4d or 5d finish nails or
1 1/2-inch brads to fasten the timer edge of the casing
to the jamb. For hardwood casing, it is advisable to
predrill to prevent splitting. Nails in the casing should
be located in pairs and spaced about 16 inches apart
along the full height of the opening at the head jamb.
The door opening is now complete except for fitting
and securing the hardware and nailing the stops in
proper position. Interior doors are normally hung with
two 3 1/2-by 3 1/2-inch loose-pin butt hinges. The door
is fitted into the opening with the clearances shown in
Casing with any form of molded shape must have a
mitered joint at the comers (fig. 6-26, view B). When
Some manufacturers supply prefitted doorjambs
and doors with the hinge slots routed and ready for
installation. A similar door buck (jamb) of sheet metal
with formed stops and casing is also available.
Hardware for doors is available in a number of
finishes, with brass, bronze, and nickel being the most
common. Door sets are usually classified as entry lock
for interior doors; bathroom set (inside lock control with
safety slot for opening from the outside); bedroom lock
(keyed lock); and passage set (without lock).
As mentioned earlier, doors should be hinged so that
they open in the direction of natural entry. ‘hey should
also swing against a blank wall whenever possible and
never into a hallway. The door swing directions and
sizes are usually shown on the working drawings. The
“hand of the door” (fig. 6-28) is the expression used to
describe the direction in which a door is to swing
(normal or reverse) and the side from which it is to hang
(left or right).
When ordering hardware for a door, be sure to
specify whether it is a left-hand door, a right-hand door,
a left-hand reverse door, or a right-hand reverse door.
Figure 6-27.—Door clearances.
You should use three hinges for hanging 1 3/4-inch
exterior doors and two hinges for the lighter interior
doors. The difference in exposure on the opposite sides
of exterior doors causes a tendency to warp during the
winter. Three hinges reduce this tendency. Three hinges
are also useful on doors that lead to unheated attics and
for wider and heavier doors that may be used within the
structure. If a third hinge is required center it between
the top and bottom hinges.
figure 6-27. The clearance and location of hinges,
lockset, and doorknob may vary somewhat, but they are
generally accepted by craftsmen and conform to most
millwork standards. The edge of the lock stile should be
beveled slightly to permit the door to clear the jamb
when swung open. If the door is to swing across heavy
carpeting, the bottom clearance may need to be slightly
When fitting doors, you should temporarily nail the
stop in place; this stop will be nailed in permanently
when the door has been hung. Stops for doors in
single-piece jambs are generally 7/16 inch thick and
may be 3/4 inch to 2 1/4 inches wide. They are installed
with a mitered joint at the junction of the side and head
jambs. A 45° bevel cut at the bottom of the stop, about
1 to 1 1/2 inches above the finish floor, eliminates a dirt
Loose-pin butt hinges should be used and must
be of the proper size for the door they support.
For 1 3/4-inch-thick doors, use 4- by 4-inch butts; for
1 3/8-inch doors, you should use 3 1/2- by 3 1/2-inch
butts. After the door is fitted to the tied opening with
the proper clearances, hinge halves are fitted to the door.
They are routed into the door edge with about a
3/16-inch back distance (fig. 6-29, view A). One hinge
half should be set flush with the surface and must be
fastened square with the edge of the door. Screws are
included with each pair of hinges.
pocket and makes cleaning or refinishing of the floor
easier (fig. 6-26, view A).
Figure 6-28.—“ Hands” of doors.
Figure 6-29.—Installation of door hardware.
view B). A bored lockset (view C) is easy to install since
it requires only one hole drilled in the edge and one in
the face of the door. Boring jigs and faceplate markers
are available to ensure accurate installation.
The lock should be installed so that the doorknob is
36 to 38 inches above the floor line. Most sets come with
paper templates, marking the location of the lock and
size of the holes to be drilled. Be sure to read the
manufacturer’s installation instructions carefully.
Recheck your layout measurements before you drill any
Figure 6-30.—Parts of a cylinder lock.
The door should now be placed in the opening and
blocked up at the bottom for proper clearance. The jamb
should be marked at the hinge locations, and the
remaining hinge half routed and fastened in place. The
door should then be positioned in the opening and the
pins slipped in place. If you have installed the hinges
correctly and the jambs are plumb, the door should
swing freely.
The parts of an ordinary cylinder lock for a door are
shown in figure 6-30. The procedure for installing a lock
of this type is as follows:
1. Open the door to a convenient working position
and check it in place with wedges under the
bottom near the outer edge.
2. Measure up 36 inches from the floor (the usual
knob height), and square a line across the face
and edge of the lock stile.
The types of door locks differ with regard to
installation, cost, and the amount of labor required to set
them. Some types, such as mortise locks, combination
dead bolts, and latch locksets, require drilling of the
edge and face of the door and then routing of the edge
to accommodate the lockset and faceplate (fig, 6-29,
3. Place the template, which is usually supplied
with a cylinder lock, on the face of the door at
the proper height and alignment with layout
lines and mark the centers of the holes to be
drilled. (A typical template is shown in fig.
Figure 6-31.—Drill template for locksets.
Figure 6-32.—Door details.
4. Drill the holes through the face of the door and
then the hole through the edge to receive the
latch bolt. It should be slightly deeper than the
length of the bolt.
be flush with or slightly below the face of the doorjamb.
When the door is latched, its face should be flush with
the edge of the jamb.
5. Cut again for the latch-bolt mounting plate, and
install the latch unit.
6. Install the interior and exterior knobs.
The stops that have been temporarily set during the
fitting of the door and the hardware may now be nailed
in permanently. You should use finish nails or brads,
1 1/2 inches long. The stop at the lock side (fig. 6-32,
view B) should be nailed first, setting it tight against the
door face when the door is latched. Space the nails in
pairs 16 inches apart.
7. Find the position of the strike plate and install it
in the jamb.
Strike Plates
The stop behind the hinge side should be nailed
next, and a 1/32-inch clearance from the door face
should be allowed to prevent scraping as the door is
opened. The head-jamb stop should then be nailed in
place. Remember that when the door and trim are
painted, some of the clearance will be taken up.
The strike plate, which is routed into the doorjamb,
holds the door in place by contact with the latch. To
install, mark the location of the latch on the doorjamb
and locate the position of the strike plate by outlining it.
Rout out the marked outline with a chisel and also rout
for the latch (fig. 6-32, view A). The strike plate should
Figure 6-33.—Commercial hardware.
The items of commercial/industial door hardware
shown in figure 6-33 are usually installed in commercial
or industrial buildings, not residential housing. These
items are used where applicable, in new construction or
in alterations or repairs of existing facilities. Most of
these items are made for use in or on metal doors, but
some items are made for wood doors. Follow the
manufacturer’s installation instructions. Recommended
door hardware locations for standard steel doors are
shown in figure 6-34. Standard 7-foot doors are usually
used in commercial construction.
this section, you should be able to identify the
types of interior wood trim and the associated
installation procedures.
The casing around the window frames on the
interior of a structure should be the same pattern as that
used around the interior doorframes. Other trim used for
a double-hung window frame includes the sash, stops,
stool, and apron (fig. 6-35, view A). Another method of
using trim around windows has the entire opening
Figure 6-34.-Location of hardware for steel doors.
enclosed with casing (fig. 6-35, view B). The stool
serves as a filler trim member between the bottom sash
rail and the bottom casing.
The stool is the horizontal trim member that laps the
windowsill and extends beyond the casing at the sides,
with each end notched against the plastered wall. The
apron serves as a finish member below the stool. The
window stool is the first piece of window trim to be
installed and is notched and fitted against the edge of the
jamb and plaster line, with the outside edge being flush
against the bottom rail of the window sash. The stool is
blind-nailed at the ends so that the casing and the stop
cover the nailheads. Prechilling is usually necessary to
prevent splitting. The stool should also be nailed at the
midpoint of the sill and to the apron with finishing nails.
Face-nailing to the sill is sometimes substituted or
supplemented with toenailing of the outer edge to the
The window casing should be installed and nailed
as described for doorframes (fig. 6-26, view A) except
for the inner edge. This edge should be flush with the
inner face of the jambs so that the stop covers the joint
between the jamb and casing. The window stops are then
nailed to the jambs so that the window sash slides
smoothly. Channel-type weather stripping often
Figure 6-35.—Installation of window trim.
includes full-width metal subjambs into which the upper
and lower sash slide, replacing the parting strip. Stops
are located against these instead of the sash to provide
a small amount of pressure. The apron is cut to a length
equal to the outer width of the casing line (fig. 6-35, view
A). It should be nailed to the windowsill and to the 2by 4-inch framing sill below.
When casing is used to finish the bottom of the
window frame, as well as the sides and top, the narrow
stool butts against the side window jamb. Casing should
then be mitered at the bottom comers (fig. 6-35, view
B) and nailed as previously described.
Base molding serves as a finish between the finished
wall and floor. It is available in several widths and
forms. Two-piece base consists of a baseboard topped
with a small base cap (fig. 6-36, view A). When plaster
is not straight and true, the small base molding will
conform more closely to the variations than will the
wider base alone. A common size for this type of
baseboard is 5/8 inch by 3 1/4 inches or wider. One-piece
base varies in size from 7/16 inch by 2 1/4 inches to
1/2 inch by 3 1/4 inches and wider (fig. 6-36, views B
and C). Although a baseboard is desirable at the junction
of the wall and carpeting to serve as a protective bumper,
wood trim is sometimes eliminated entirely.
Figure 6-36.-Base moldings.
Most baseboards are finished with a 1/2-by 3/4-inch
base shoe (fig. 6-36, view A). A single base molding
without the shoe is sometimes placed at the wall-floor
junction, especially where carpeting might be used.
Square-edged baseboard should be installed with a
butt joint at the inside comers and a mitered joint at the
outside comers (fig. 6-36, view D). It should be nailed
to each stud with two 8d finishing nails. Molded
single-piece base, base moldings, and base shoe should
have a coped joint at the inside corners and a mitered
joint at the outside corners. In a coped joint, the first
piece is square-cut against the plaster or base and the
second piece of molding coped. This is done by sawing
a 45° miter cut and using a coping saw to trim the
molding along the inner line of the miter (fig. 6-36, view
E). The base shoe should be nailed into the baseboard
itself. Then, if there is a small amount of shrinkage of
the joists, no opening will occur under the shoe.
To butt-join a piece of baseboard to another piece
already in place at an inside corner, set the piece to be
joined in position on the floor, bring the end against or
near the face of the other piece, and take off the line of
the face with a scriber (fig. 6-37). Use the same
procedure when butting ends of the baseboard against
the side casings of the doors.
For miter-joining at an outside comer, proceed as
shown in figure 6-38. First, set a marker piece of
baseboard across the wall comer, as shown view A, and
mark the floor along the edge of the piece. Then set the
piece to be mitered in place. Mark the point where the
wall corner intersects the top edge and the point where
Figure 6-37.-Butt-joining baseboard at inside corners.
Figure 6-38.-Miter-joining at inside corners.
the mark on the floor intersects the bottom edge. Lay
45° lines across the edge from these points to make a
90° corner. Connect these lines with a line across the
face (view B), and miter to the lines as indicated.
The most economical, and sometimes the quickest,
method of installing baseboard is to use vinyl. In
addition to its flexibility, it comes with premolded inside
and outside corners. When installing vinyl base, follow
the manufacturer’s recommended installation
procedures for both the base and adhesive.
Figure 6-39.-Ceiling moldings.
Interior finish to be painted should be smooth,
close-grained, and free from pitch streaks. Species
meeting these requirements include ponderosa pine,
northern white pine, redwood, and spruce. Birch, gum,
and yellow poplar are recommended for their hardness
and resistance to hard usage. Ash, birch, cherry, maple,
oak, and walnut provide a beautiful natural finish
decorative treatment. Some require staining to improve
Ceiling moldings (fig. 6-39) are sometimes used at
the junction of the wall and ceiling for an architectural
effect or to terminate drywall paneling of gypsum board
or wood. As with base moldings, inside corners should
be cope-jointed (fig. 6-39, view A). This ensures a tight
joint and retains a good fit if there are minor moisture
A cutback edge at the outside of the molding (view
B) partially conceals any unevenness of the plaster and
makes painting easier where there are color changes. For
gypsum drywall construction, a small, simple molding
(view C) might be desirable. Finish nails should be
driven into the upper wall plates and also into the ceiling
joists for large molding when possible.
Although the following references
were current when this TRAMAN was
published, their continued currency
cannot be assured. You therefore need
to ensure that you are studying the
latest revisions.
Carpentry, Leonard Keel, American Technical
Publishers, Inc., Alsip, Ill., 1985.
Exterior and Interior Trim, John E. Ball, Delmar
Publishers, Inc., Albany, N.Y, 1975.
The decorative treatment for interior doors, trim,
and other millwork may be painted or given a natural
finish with stain, varnish, or other nonpigmented
material. The paint or natural finish desired for the
woodwork in various rooms often determines the
species of wood to be used.
Wood Frame House Construction, L.O. Anderson,
Forest Products Laboratory, U.S. Forest Service,
U.S. Department of Agriculture, Washington, D.C.,
material is then ground to a fine powder. Additives are
used to control set, stabilization, and other physical or
chemical characteristics.
Plaster and stucco are like concrete in that they are
construction materials applied in a plastic condition that
harden in place. They are also basically the same
material. The fundamental difference between the two
is location. If used internally, the material is called
plaster; if used externally, it is called stucco. Ceramic
tile is generally used to partially or entirely cover
interior walls, such as those in bathrooms, showers,
galleys, and corridors. The tile is made of clay, pressed
into shape, and baked in an oven.
For a type of gypsum plaster called Keene’s cement,
the crushed gypsum rock is heated until nearly all the
crystallization water is removed. The resulting material,
called Keene’s cement, produces a very hard,
fine-textured finish coat.
The removal of crystallization water from natural
gypsum is a dehydration process. In the course of
setting, mixing water (water of hydration) added to the
mix dehydrates with the gypsum, causing
recrystallization. Recrystallization results in hardening
of the plaster.
This chapter provides information on the
procedures, methods, and techniques used in plastering,
stuccoing, and tile setting. Also described are various
tools, equipment, and materials the Builder uses when
working with these materials.
Base Coats
There are four common types of gypsum base coat
plasters. Gypsum neat plaster is gypsum plaster without
aggregate, intended for mixing with aggregate and water
on the job. Gypsum ready-mixed plaster consists of
gypsum and ordinary mineral aggregate. On the job, you
just add water. Gypsum wood-fibered plaster consists of
calcined gypsum combined with at least 0.75 percent by
weight of nonstaining wood fibers. It maybe used as is
or mixed with one part sand to produce base coats of
superior strength and hardness. Gypsum bond plaster is
designed to bond to properly prepared monolithic
concrete. This type of plaster is basically calcined
gypsum mixed with from 2-to 5-percent lime by weight.
this section, you should be able to identify
plaster ingredients, state the principles of mix
design, and describe common types and uses of
gypsum plaster.
A plaster mix, like a concrete mix, is made plastic
by the addition of water to dry ingredients (binders and
aggregates). Also, like concrete, a chemical reaction of
the binder and the water, called hydration, causes the
mix to harden.
The binders most commonly used in plaster are
gypsum, lime, and portland cement. Because gypsum
plaster should not be exposed to water or severe
moisture conditions, it is usually restricted to interior
use. Lime and portland cement plaster maybe used both
internally and externally. The most commonly used
aggregates are sand, vermiculite, and perlite.
Finish Coats
There are five common types of gypsum-finish coat
Ready-mix gypsum-finish plasters are designed for
use over gypsum-plaster base coats. They consist of
finely ground calcined gypsum, some with aggregate
and others without. On the job, just add water.
Gypsum is a naturally occurring sedimentary gray,
white, or pink rock. The natural rock is crushed, then
heated to a high temperature. This process (known as
calcining) drives off about three-quarters of the water of
crystallization, which forms about 20 percent of the
weight of the rock in its natural state. The calcined
Gypsum acoustical plasters are designed to reduce
sound reverberation. Gypsum gauging plasters contain
lime putty. The putty provides desirable setting
properties, increases dimensional stability during
drying, and provides initial surface hardness.
For interior base coat work, lime plaster has been
largely replaced by gypsum plaster. Lime plaster is now
used mainly for interior finish coats. Because lime putty
is the most plastic and workable of the cementitious
materials used in plaster, it is often added to other less
workable plaster materials to improve plasticity. For
lime plaster, lime (in the form of either dry hydrate or
lime putty) is mixed with sand, water, and a gauging
material. The gauging material is intended to produce
early strength and to counteract shrinkage tendencies. It
can be either gypsum gauging plaster or Keene’s cement
for interior work or portland cement for exterior work.
When using gauging plaster or Keene’s cement, mix
only the amount you can apply within the initial set time
of the material.
Gauging plasters are obtainable in slow-set,
quick-set, and special high-strength mixtures.
Gypsum molding plaster is used primarily in casting
and ornamental plasterwork. It is available neat (that is,
without admixtures) or with lime. As with Portland
cement mortar, the addition of lime to a plaster mix
makes the mix more “buttery.”
Keene’s cement is a fine, high-density plaster
capable of a highly polished surface. It is customarily
used with fine sand, which provides crack resistance.
Lime is obtained principally from the calcining of
limestone, a very common mineral. Chemical changes
occur that transform the limestone into quicklime, a very
caustic material. When it comes in contact with water,
a violent reaction, hot enough to boil the water, occurs.
Portland cement plaster is similar to the Portland
cement mortar used in masonry. Although it may contain
only cement, sand, and water, lime or some other
plasterizing material is usually added for “butteriness.”
Today, the lime manufacturers slake the lime as part
of the process of producing lime for mortar. Slaking is
done in large tanks where water is added to convert the
quicklime to hydrated lime without saturating it with
water. The hydrated lime is a dry powder with just
enough water added to supply the chemical reaction.
Hydration is usually a continuous process and is done
in equipment similar to that used in calcining. After the
hydrating process, the lime is pulverized and bagged.
When received by the plasterer, hydrated lime still
requires soaking with water.
Portland cement plaster can be applied directly to
exterior and interior masonry walls and over metal lath.
Never apply portland cement plaster over gypsum
plasterboard or over gypsum tile. Portland cement
plaster is recommended for use in plastering walls and
ceilings of large walk-in refrigerators and cold-storage
spaces, basements, toilets, showers, and similar areas
where an extra hard or highly water-resistant surface is
In mixing medium-slaking and slow-slaking limes,
you should add the water to the lime. Slow-slaking lime
must be mixed under ideal conditions. It is necessary to
heat the water in cold Magnesium lime is easily
drowned, so be careful you don’t add too much water to
quick-slaking calcium lime. When too little water is
added to calcium and magnesium limes, they can be
burned. Whenever lime is burned or drowned, a part of
it is spoiled It will not harden and the paste will not be
as viscous and plastic as it should be. To produce plastic
lime putty, soak the quicklime for an extended period,
as much as 21 days.
As we mentioned earlier, there are three main
aggregates used in plaster: sand, vermiculite, and
perlite. Less frequently used aggregates are wood fiber
and pumice.
Sand for plaster, like sand for concrete, must contain
no more than specified amounts of organic impurities
and harmful chemicals. Tests for these impurities and
chemicals are conducted by Engineering Aids.
Because of the delays involved in the slaking
process of quicklime, most building lime is the hydrated
type. Normal hydrated lime is converted into lime putty
by soaking it for at least 16 hours. Special hydrated lime
develops immediate plasticity when mixed with water
and may be used right after mixing. Like calcined
gypsum, lime plaster tends to return to its original
rock-like state after application.
Proper aggregate gradation influences plaster
strength and workability. It also has an effect on the
tendency of the material to shrink or expand while
setting. Plaster strength is reduced if excessive fine
aggregate material is present in a mix. The greater
quantity of mixing water required raises the
water-cement ratio, thereby reducing the dry-set
as wood fiber and pumice, are also used. Wood fiber may
be added to neat gypsum plaster, at the time of
manufacture, to improve its working qualities. Pumice
is a naturally formed volcanic glass similar to perlite,
but heavier (28 to 32 pounds per cubic foot versus 7.5
to 15 pounds for perlite). The weight differential gives
perlite an economic advantage and limits the use of
pumice to localities near where it is produced.
density. The cementitious material becomes overextended since it must coat a relatively larger overall
aggregate surface. An excess of coarse aggregate
adversely affects workability-the mix becomes harsh
working and difficult to apply.
Plaster shrinkage during drying can be caused by an
excess of either fine or coarse aggregate. You can
minimize this problem by properly proportioning the
raw material, and using good, sharp, properly sizegraded sand.
In plaster, mixing water performs two functions.
First, it transforms the dry ingredients into a plastic,
workable mass. Second, it combines with the binder to
induce hardening. As with concrete, there is a maximum
quantity of water per unit of binder required for
complete hydration; an excess over this amount reduces
the plaster strength.
Generally, any sand retained on a No. 4 sieve is too
coarse to use in plaster. Only a small percentage of the
material (about 5 percent) should pass the No. 200 sieve.
Vermiculite is a micaceous mineral (that is, each
particle is laminated or made up of adjoining layers).
When vermiculite particles are exposed to intense heat,
steam forms between the layers, forcing them apart.
Each particle increases from 6 to 20 times in volume.
The expanded material is soft and pliable with a color
varying between silver and gold.
In all plaster mixing, though, more water is added
than is necessary for complete hydration of the binder.
The excess is necessary to bring the mix to workable
consistency. The amount to be added for workability
depends on several factors: the characteristics and age
of the binder, application method, drying conditions,
and the tendency of the base to absorb water. A porous
masonry base, for example, draws a good deal of water
out of a plaster mix. If this reduces the water content of
the mix below the maximum required for hydration,
incomplete curing will result.
For ordinary plasterwork vermiculite is used only
with gypsum plaster; therefore, its use is generally
restricted to interior applications. For acoustical plaster,
vermiculite is combined with a special acoustical binder.
The approximate dry weight of a cubic foot of 1:2
gypsum-vermiculite plaster is 50 to 55 pounds. The dry
weight of a cubic foot of comparable sand plaster is 104
to 120 pounds.
As a general rule, only the amount of water required
to attain workability is added to a mix. The water should
be potable and contain no dissolved chemicals that
might accelerate or retard the set. Never use water
previously used to wash plastering tools for mixing
plaster. It may contain particles of set plaster that may
accelerate setting. Also avoid stagnant water; it may
contain organic material that can retard setting and
possibly cause staining.
Raw perlite is a volcanic glass that, when flashroasted, expands to form irregularly shaped frothy
particles containing innumerable minute air cells. The
mass is 4 to 20 times the volume of the raw partlicles.
The color of expanded perlite ranges from pearly white
to grayish white.
this section, you should be able to associate the
names and purposes of each type of lath used
as a plaster base. You should also be able to
describe the procedures used in plastering,
including estimating materials and the
procedures for mixing and applying plaster
Perlite is used with calcined gypsum or portland
cement for interior plastering. It is also used with special
binders for acoustical plaster. The approximate dry
weight of a cubic foot of 1:2 gypsum-perlite plaster is
50 to 55 pounds, or about half the weight or a cubic foot
of sand plaster.
Wood Fiber and Pumice
Although sand, vermiculite, and perlite makeup the
great majority of plaster aggregate, other materials, such
For plastering, there must be a continuous surface
to which the plaster can be applied and to which it will
cling—the plaster base. A continuous concrete or
masonry surface may serve as a base without further
For plaster bases, such as those defined by the inner
edges of the studs or the lower edges of the joists, a base
material, called lath, must be installed to form a
continuous surface spanning the spaces between the
structural members.
Wood Lath
Wood lath is made of white pine, spruce, fir,
redwood, and other soft, straight-grained woods. The
standard size of wood lath is 5/16 inch by 1 1/2 inches
by 4 feet. Each lath is nailed to the studs or joists with
3-penny (3d) blued lathing nails.
Laths are nailed six in a row, one above the other.
The next six rows of lath are set over two stud places.
The joints of the lath are staggered in this way so cracks
will not occur at the joinings. Lath ends should be spaced
1/4 inch apart to allow movement and prevent buckling.
Figure 7-1 shows the proper layout of wood lath. To
obtain a good key (space for mortar), space the laths not
less than 3/8 inch apart. Figure 7-2 shows good spacing
with strong keys.
Wood laths come 50 to 100 to the bundle and are
sold by the thousand. The wood should be straightgrained, and free of knots and excessive pitch. Don’t use
old lath; dry or dirty lath offers a poor bonding surface.
Lath must be damp when the mortar is applied Dry lath
pulls the moisture out of the mortar, preventing proper
setting. The best method to prevent dry lath is to wet it
thoroughly the day before plastering. This lets the wood
swell and reach a stable condition ideal for plaster
Figure 7-2.—Wood lath, showing proper keys.
Board Lath
Of the many kinds of lathing materials available,
board lath is the most widely used today. Board lath is
manufactured from mineral and vegetable products. It
is produced in board form, and in sizes generally
standardized for each application to studs, joists, and
various types of wood and metal timing.
Board lath has a number of advantages. It is rigid,
strong, stable, and reduces the possibility of dirt filtering
through the mortar to stain the surface. It is insulating
and strengthens the framework structure. Gypsum board
lath is fire resistant. Board lath also requires the least
amount of mortar to cover the surface.
Board laths are divided into two main groups:
gypsum board and insulation board. Gypsum lath is
made in a number of sizes, thicknesses, and types. Each
type is used for a specific purpose or condition. Note:
Only gypsum mortar can be used over gypsum lath.
Never apply lime mortar, portland cement, or any other
binding agent to gypsum lath.
The most commonly used size gypsum board lath is
the 3/8 inch by 16 inches by 48 inches, either solid or
perforated. This lath will not burn or transmit
temperatures much in excess of 212°F until the gypsum
is completely calcined. The strength of the bond of
plaster to gypsum lath is great. It requires a pull of
864 pounds per square foot to separate gypsum plaster
from gypsum lath (based on a 2:1 mix of sand and plaster
Figure 7-1.—Wood lath with joints staggered every sixth
Figure 7-3.—Keys formed with perforated gypsum board.
There is also a special fire-retardant gypsum lath,
called type X. It has a specially formulated core,
containing minerals giving it additional fire protection.
Use only one manufacturer’s materials for a
specified job or area. This ensures compatibility. Always
strictly follow the manufacturer’s specifications for
materials and conditions of application.
Plain gypsum lath plaster base is used in several
situations: for applying nails and staples to wood and
nailable steel framing; for attaching clips to wood
framing, steel studs, and suspended metal grillage; and
for attaching screws to metal studs and furring channels.
Common sizes include 16 by 48 inches, 3/8 or 1/2 inch
thick, and 16 by 96 inches, 3/8 inch thick.
Perforated gypsum lath plaster base is the same as
plain gypsum lath except that 3/4-inch round holes are
punched through the lath 4 inches on center (OC) in each
direction. This gives one 3/4-inch hole for each
16 square inches of lath area. This provides mechanical
keys in addition to the natural plaster bond and obtains
higher fire ratings. Figure 7-3 shows back and side
views of a completed application.
Insulating gypsum lath plaster base is the same as
plain gypsum lath, but with bright aluminum foil
laminated to the back. This creates an effective vapor
barrier at no additional labor cost. In addition, it
provides positive insulation when installed with the foil
facing a 3/4-inch minimum air space. When insulating
gypsum lath plaster is used as a ceiling, and under winter
heating conditions, its heat-resistance value is
approximately the same as that for 1/2-inch insulation
Long lengths of gypsum lath are primarily used for
furring the interior side of exterior masonry walls. It is
available in sizes 24 inches wide, 3/8 inch thick, and up
to 12 feet in length.
Figure 7-4.-Types of metal lath.
Gypsum lath is easily cut by scoring one or both
sides with a utility knife. Break the lath along the scored
line. Be sure to make neatly fitted cutouts for utility
openings, such as plumbing pipes and electrical outlets.
Metal Lath
Metal lath is perhaps the most versatile of all plaster
bases. Essentially a metal screen, the bond is created by
keys formed by plaster forced through the openings. As
the plaster hardens, it becomes rigidly interlocked with
the metal lath.
Three types of metal lath are commonly used:
diamond mesh (expanded metal), expanded rib, and
wire mesh (woven wire). These are shown in figure 7-4.
DIAMOND MESH.— The terms “diamond mesh”
and “expanded metal” refer to the same type of lath
(fig. 7-4). It is manufactured by first cutting staggered
slits in a sheet and then expanding or stretching the sheet
to form the screen openings. The standard diamond
mesh lath has a mesh size of 5/16 by 9/16 inch. Lath is
made in sheets of 27 by 96 inches and is packed 10 sheets
to a bundle (20 square yards).
Diamond mesh lath is also made in a large mesh.
This is used for stucco work, concrete reinforcement,
and support for rock wool and similar insulating
materials. Sheet sizes are the same as for the small mesh.
The small diamond mesh lath is also made into a
self-furring lath by forming dimples into the surface that
hold the lath approximately 1/4 inch away from the wall
surface. This lath may be nailed to smooth concrete or
masonry surfaces. It is widely used when replastering
old walls and ceilings when the removal of the old
plaster is not desired. Another lath form is paper-backed
where the lath has a waterproof or kraft paper glued to
the back of the sheet. The paper acts as a moisture barrier
and plaster saver.
Figure 7-5.-Lath joints.
EXPANDED RIB.— Expanded rib lath (fig. 7-4) is
like diamond mesh lath except that various size ribs are
formed in the lath to stiffen it. Ribs run lengthwise of
the lath and are made for plastering use in 1/8-, 3/8-, and
3/4-inch rib height. The sheet sizes are 27 to 96 inches
in width, and 5-,10-, and 12-foot lengths for the 3/4-inch
rib lath.
staples have gained wider use (due mainly to the ready
availability of power guns).
The nails used are 1 1/8 inches by 13 gauge, flat
headed, blued gypsum lath nails for 3/8-inch-thick
boards and 1 1/4 inches for 1/2-inch boards. There are
also resin-coated nails, barbed-shaft nails, and
screw-type nails in use. Staples should be No. 16 U.S.
gauge flattened galvanized wire formed with a
7/16-inch-wide crown and 7/8-inch legs with divergent
points for 3/8-inch lath. For 1/2-inch lath, use
1-inch-long staples.
WIRE MESH.— Woven wire lath (fig. 7-4) is made
of galvanized wire of various gauges woven or twisted
together to form either squares or hexagons. It is
commonly used as a stucco mesh where it is placed over
tar paper on open-stud construction or over various
Four nails or staples are used on each support for
16-inch-wide lath and five for 2-foot-wide lath. Some
special fire ratings, however, require five nails or staples
per 16-inch board. Five nails or staples are also
recommended when the framing members are spaced
24 inches apart.
Let’s now look at the basic installation procedures
for plaster bases and accessories.
Gypsum Lath
Start nailing or stapling 1/2 inch from the edges of
the board. Nail on the framing members falling on the
center of the board first, then work to either end. This
should prevent buckling.
Gypsum lath is applied horizontally with staggered
end joints, as shown in figure 7-5. Vertical end joints
should be made over the center of studs or joists. Lath
joints over openings should not occur at the jamb line.
Do not force the boards tightly together; let them butt
loosel y so the board is not under compression before the
plaster is applied. Use small pieces only where
necessary. The most common method of attaching the
boards has been the lath nail. More recently, though,
Insulating lath should be installed much the same as
gypsum lath except that slightly longer blued nails are
used. A special waterproof facing is provided on one
type of gypsum board for use as a ceramic tile base when
the tile is applied with an adhesive.
Metal Lath
All metal lath is installed with the sides and ends
lapped over each other. The laps between supports
should be securely tied, using 18-gauge tie wire. In
general, metal lath is applied with the long length at right
angles to the supports. Rib lath is placed with the ribs
against the supports and the ribs nested where the lath
overlaps. Generally, metal lath and wire lath are lapped
at least 1 inch at the ends and 1/2 inch at the sides. Some
wire lath manufacturers specify up to 4 1/2-inch end
lapping and 2-inch side laps. This is done to mesh the
wires and the paper backing.
Lath is either nailed, stapled, or hog-tied (heavy
wire ring installed with a special gun) to the supports at
6-inch intervals. Use 1 1/2-inch barbed roofing nails
with 7/16-inch heads or 1 inch 4-gauge staples for the
flat lath on wood supports. For ribbed lath, heavy wire
lath, and sheet lath, nails or staples must penetrate the
wood 1 3/8 inches for horizontal application and at least
3/4 inch for vertical application. When common nails
are used, they must be bent across at least three lath
Figure 7-6.—Perforated flanged corner bead.
the lath. These include prefabricated metal studs and
floor and ceiling runner tracks. The runner tracks take
the place of missing stud top and bottom plates. They
usually consist of metal channels. Channels are also
used for furring and bracing.
On channel iron supports, the lath is tied with No.
18-gauge tie wire at 4-inch intervals using lathers’
nippers. For wire lath, the hog tie gun can be used. Lath
must be stretched tight as it is applied so that no sags or
buckles occur. Start tying or nailing at the center of the
sheet and work toward the ends. Rib lath should have
ties looped around each rib at all supports, as the main
supporting power for rib lath is the rib.
Miscellaneous accessories consist of components
attached to the lath at various locations. They serve to
define and reinforce comers, provide dividing strips
between plaster and the edges of baseboard or other
trim, and define plaster edges at unframed openings.
When you install metal laths at both inside and
outside corners, bend the lath to forma comer and carry
it at least 4 inches in or around the corner. This provides
the proper reinforcement for the angle or comer.
Comer beads fit over gypsum lath outside corners
to provide a true, reinforced comer. They are available
in either small-nose or bullnose types, with flanges of
either solid or perforated (fig. 7-6) metal. They are
available with expanded metal flanges.
Lath Accessories
Casing beads are similar to comer beads and are
used both as finish casings around openings in plaster
walls and as screeds to obtain true surfaces around doors
and windows. They are also used as stops between a
plaster surface and another material, such as masonry or
wood paneling. Casing beads are available as square
sections, modified-square sections, and quarter-rounds.
A wide variety of metal accessories is produced for
use with gypsum and metal lathing. Lathing accessories
are usually installed before plastering to form true
corners, act as screeds for the plasterer, reinforce
possible weak points, provide control joints, and
provide structural support.
Base or parting screeds are used to separate plaster
from other flush surfaces, such as concrete. Ventilating
expansion screed is used on the underside of closed
soffits and in protected vertical surfaces for ventilation
of enclosed attic spaces. Drip screeds act as terminators
of exterior portland cement plaster at concrete
foundation walls. They are also used on external
horizontal comers of plaster soffits to prevent drip stains
Lathing accessories consist of structural components and miscellaneous accessories. The principal
use of structural components is in the construction of
hollow partitions. A hollow partition is one containing
no building framing members, such as studs and plates.
Structural components are lathing accessories that take
the place of the missing framing members supporting
on the underside of the soffit. A metal base acts as a flush
base at the bottom of a plaster wall. It also serves as a
plaster screed.
Joint Reinforcing
Because some drying usually takes place in the
wood framing members after a structure is completed,
some shrinkage is expected. This, in turn, may cause
plaster cracks to develop around openings and in the
comers. To minimize, if not eliminate, these cracks, use
expanded metal lath in key positions over the plasterbase material as reinforcements. Strip reinforcement
(strips of expanded metal lath) can be used over door
and window openings (fig. 7-7, view A). A 10- to
20-inch strip is placed diagonally across each upper
comer of the opening and tacked in place.
Strip reinforcement should also be used under flush
ceiling beams (fig. 7-7, view B) to prevent plaster
cracks. On wood drop beams extending below the
ceiling line, the metal lath is applied with furring nails
to provide space for keying the plaster.
Figure 7-7.-Metal lath used to minimize cracking.
Corner beads of expanded metal lath or of
perforated metal (fig. 7-8) should be installed on all
outside comers. They should be applied plumb and
level. Each bead acts as a leveling edge when walls are
plastered and reinforces the comer against mechanical
damage. To minimize plaster cracks, reinforce the inside
comers at the juncture of walls and ceilings. Metal lath,
or wire fabric, is tacked lightly in place in these corners.
Control joints (an example of which is shown in
fig. 7-9) are formed metal strips used to relieve stresses
and strains in large plaster areas or at junctures of
dissimilar materials on walls and ceilings. Cracks can
develop in plaster or stucco from a single cause or a
combination of causes, such as foundation settlement,
material shrinkage, building movement, and so forth. The
control joint minimizes plaster cracking and assures
proper plaster thickness. The use of control joints is
extremely important when Portland cement plaster is
Plastering Grounds
Plastering grounds are strips of wood used as
plastering guides or strike-off edges and are located
around window and door openings and at the base of the
walls. Grounds around interior door openings (such as
fig. 7-10, view A) are full-width pieces nailed to the
sides over the studs and to the underside of the header.
They are 5 1/4 inches wide, which coincides with the
standard jamb width for interior walls with a plaster
Figure 7-8.-Plaster reinforcing at corners.
Figure 7-9.-Control joint.
finish. They are removed after the plaster has dried.
Narrow strip grounds (fig. 7-10, view B) can also be
used around interior openings.
In window and exterior door openings, the frames
are normally in place before the plaster is applied. Thus,
the inside edges of the side and head jamb can, and often
do, serve as grounds. The edge of the window might also
be used as a ground, or you can use a narrow
7/8-inch-thick ground strip nailed to the edge of the 2by 4-inch sill (fig. 7-10, view C). These are normally
left in place and covered by the casing.
Figure 7-10.—Plaster grounds.
workability. For job mixing, tables are available giving
recommended ingredient proportions for gypsum, lime,
lime-portland cement, and portland cement plaster for
base coats on lath or on various types of concrete or
masonry surfaces, and for finish coats of various types.
In this chapter, we’ll cover recommended proportions
for only the more common types of plastering situations.
A similar narrow ground or screed is used at the
bottom of the wall to control the thickness of the gypsum
plaster and to provide an even surface for the baseboard
and molding. This screed is also left in place after the
plaster has been applied.
In the following discussion, one part of cementitious material means 100 pounds (one sack) of gypsum,
100 pounds (two sacks) of hydrated lime, 1 cubic foot
Some plaster comes ready-mixed, requiring only
the addition of enough water to attain minimum required
Table 7-1.—Base Coat Proportions for Different Types of Work
can be applied over a lime, gypsum, or portland cement
of lime putty, or 94 pounds (one sack) of portland
cement. One part of aggregate means 100 pounds of
sand or 1 cubic foot of vermiculite or perlite. Note:
Vermiculite and perlite are not used with lime plaster.
While aggregate parts given for gypsum or portland
cement plaster may be presumed to refer to either sand
or vermiculite/perlite, the aggregate part given for lime
plaster means sand only.
base coat. Other finishes should be applied only to base
coats containing the same cementitious material. A
gypsum-vermiculite finish should be applied only to a
gypsum-vermiculite base coat.
Finish coat proportions vary according to whether
plasterwork consists of a single base coat and a finish
coat. Three-coat plasterwork consists of two base coats
(the scratch coat and the brown coat) and a finish coat.
the surface is to be finished with a trowel or with a float.
(These tools are described later.) The trowel attains a
Portland cement plaster cannot be applied to a
gypsum base. Lime plaster can, but, in practice, only
gypsum plaster is applied to gypsum lath as a base coat.
For two-coat work on gypsum lath, the recommended
base coat proportions for gypsum plaster are 1:2.5. For
two-coat work on a masonry (either monolithic concrete
or masonry) base, the recommended base coat
proportions are shown in table 7-1. Also shown in table
7-1 are proportions for three-coat work on a masonry
base and proportions for work on metal lath.
recommended proportions are 200 pounds of hydrated
smooth finish; the float produces a textured finish.
For a trowel-finish coat using gypsum plaster, the
lime or 5 cubic feet of lime putty to 100 pounds of
gypsum gauging plaster.
Table 7-2.—Recommended Base Coat Proportions for Gypsum
For three-coat work on gypsum lath, the recommended base coat proportions for gypsum plaster are
shown in table 7-2.
For a trowel-finish coat using lime-Keene’s cement
plaster, the recommended proportions are, for a
medium-hard finish, 50 pounds of hydrated lime or
100 pounds of lime putty to 100 pounds of Keene’s
cement. For a hard finish, the recommended proportions
are 25 pounds of hydrated lime or 50 pounds of lime
putty to 100 pounds of Keene’s cement.
For a trowel-finish coat using lime-portland cement
plaster, the recommended proportions are 200 prods
of hydrated lime or 5 cubic feet of lime putty to
94 pounds of Portland cement.
MIXING METHODS.— As a Builder, you will be
mixing plaster either by hand or using a machine.
Hand Mixing.— To hand-mix plaster, you will need
a flat, shallow mixing box and a hoe. The hoe usually
has one or more holes in the blade. Mixed plaster is
transferred from the mixing box to a mortar board,
similar to that used in bricklaying. Personnel applying
the plaster pick it up from the mortarboard.
In hand mixing, first place the dry ingredients in a
mixing box and thoroughly mix until a uniform color is
obtained. After thoroughly blending the dry ingredients,
you then cone the pile and add water to the mix. Begin
mixing by pulling the dry material into the water with
short strokes. Mixing is continued until the materials
have been thoroughly blended and proper consistency
has been attained. With experience, a person squires a
feel for proper consistency. Mixing should not be
continued for more than 10 to 15 minutes after the
materials have been thoroughly blended. Excessive
agitation may hasten the rate of solution of the
cementitious material and reduce initial set time.
For a finish coat using portland cement-sand plaster,
the recommended proportions are 300 pounds of sand
to 94 pounds of Portland cement. This plaster may be
either troweled or floated. Hydrated lime up to
10 percent by weight of the portland cement, or lime
putty up to 24 percent of the volume of the portland
cement, may be added as a plasticizer.
For a trowel-finish coat using gypsum gauging or
gypsum neat plaster and vermiculite aggregate, the
recommended proportions are 1 cubic foot of
vermiculite to 100 pounds of plaster.
Finish-coat lime plaster is usually hand-mixed on a
5- by 5-foot mortar board called a finishing board.
Hydrated lime is first converted to lime putty by soaking
in an equal amount of water for 16 hours. In mixing the
plaster, you first form the lime putty into a ring on the
finishing board. Next, pour water into the ring and sift
the gypsum or Keene’s cement into the water to avoid
lumping. Last, allow the mix to stand for 1 minute, then
thoroughly blend the materials. Sand, if used, is then
added and mixed in,
The total volume of plaster required for a job is the
product of the thickness of the plaster times the net area
to be covered. Plaster specifications state a minimum
thickness, which you must not go under. Also, you
should exceed the specs as little as possible due to the
increased tendency of plaster to crack with increased
Machine Mixing.— For a quicker, more thorough
mix, use a plaster mixing machine. A typical plaster
mixing machine (shown in fig. 7-11) consists primarily
of a metal drum containing mixing blades, mounted on
Mixing Plaster
The two basic operations in mixing plaster are
determining the correct proportions and the actual
mixing methods used.
PROPORTIONS.— The proper proportions of the
raw ingredients required for any plastering job are found
in the job specifications. The specs also list the types of
materials to use and the type of finish required for each
area. Hardness and durability of the plaster surface
depend upon how accurately you follow the correct
proportions. Too much water gives you a fluid plaster
that is hard to apply. It also causes small holes to develop
in the finish mortar coat. Too much aggregate in the mix,
without sufficient binder to unite the mixture, causes
aggregate particles to crumble off. Without exception,
consult the specifications prior to the commencement
of any plaster job.
Figure 7-11.—Plaster mixing machine.
a chassis equipped with wheels for road towing. Sizes
range from 3 1/2 to 10 cubic feet and can be powered
by an electric or a gasoline motor. Mixing takes place
either by rotation of the drum or by rotation of the blades
inside the drum. Tilt the drum to discharge plaster into
a wheelbarrow or other receptacle.
this section, you should be able to state the uses
of plastering tools, and describe the techniques
of plastering.
When using a plaster mixer, add the water first, then
add about half the sand. Next, add the cement and any
admixture desired. Last, add the rest of the sand. Mix
until the batch is uniform and has the proper
consistency—3 to 4 minutes is usually sufficient. Note
that excessive agitation of mortar speeds up the setting
time. Most mixers operate at top capacity when the
mortar is about 2 inches, at most, above the blades.
When the mixer is charged higher than this, proper
mixing fails to take place. Instead of blending the
materials, the mixer simply folds the material over and
over, resulting in excessively dry mix on top and too wet
mix underneath-a bad mix. Eliminate this situation by
not overloading the machine.
A plaster layer must have uniform thickness to attain
complete structural integrity. Also, a plane plaster
surface must be flat enough to appear flat to the eye and
receive surface-applied materials, such as casings and
other trim, without the appearance of noticeable spaces.
Specified flatness tolerance is usually 1/8 inch in 10 feet.
Plastering requires the use of a number of tools,
some specialized, including trowels, hawk, float,
straight and feather edges, darby, scarifier, and
plastering machines.
Handling Materials
Steel trowels are used to apply, spread, and smooth
plaster. The shape and size of the trowel blade are
determined by the purpose for which the tool is used and
the manner of using it.
Personnel handling cement or lime bags should
wear recommended personnel protective gear. Always
practice personal cleanliness. Never wear clothing that
is hard and stiff with cement. Such clothing irritates the
skin and may cause serious infection. Any susceptibility
of skin to cement and lime bums should be immediately
reported to your supervisor.
The four common types of plastering trowels are
shown in figure 7-12. The rectangular trowel, with a
blade approximately 4 1/2 inches wide by 11 inches
long, serves as the principle conveyor and manipulator
Don’t pile bags of cement or lime more than 10 bags
high on a pallet except when stored in bins or enclosures
built for such purposes. Place the bags around the
outside of the pallet with the tops of the bags facing the
center. To prevent piled bags from falling outward,
crosspile the first five tiers of bags, each way from any
comer, and make a setback starting with the sixth tier.
If you have to pile above the 10th tier, make another
setback. The back tier, when not resting against a wall
of sufficient strength to withstand the pressure, should
be set back one bag every five tiers, the same as the end
During unpiling, the entire top of the pile should be
kept level and the setbacks maintained for every five
Lime and cement must be stored in a dry place to
help prevent the lime from crumbling and the cement
from hydrating before it is used.
Figure 7-12.—Plasterting trowels.
Figure 7-15.-Straightedge and featheredge.
Figure 7-13.—Plasterting hawk.
Figure 7-16.-Darby.
Figure 7-14.—Plastering floats.
or aluminum blade. The sponge float is faced with foam
rubber or plastic, intended to attain a certain surface
of plaster. The pointing trowel, 2 inches wide and about
10 inches long, is used in places where the rectangular
trowel doesn’t fit. The margin trowel is a smaller trowel,
similar to the pointing trowel, but with a square, rather
than a pointed, end. The angle trowel is used for
finishing comer angles formed by adjoining right-angle
plaster surfaces.
In addition to the floats just mentioned, other floats
are also used in plasterwork. A carpet float is similar to
a sponge float, but faced with a layer of carpet material.
A cork float is faced with cork.
Straight and Feather Edges
The rod or straightedge consists of a wood or
lightweight metal blade 6 inches wide and 4 to 8 feet
long (see fig. 7-15). This is the first tool used in leveling
and straightening applied plaster between the grounds.
A wood rod has a slot for a handle cut near the center of
the blade. A metal rod usually has a shaped handle
running the length of the blade.
The hawk (fig. 7-13) is a square, lightweight sheetmetal platform with a vertical central handle, used for
carrying mortar from the mortar board to the place
where it is to be applied. The plaster is then removed
from the hawk with the trowel. The size of a hawk varies
from a 10- to a 14-inch square. A hawk can be made in
the field from many different available materials.
The featheredge (fig. 7-15) is similar to the rod
except that the blade tapers to a sharp edge. It is used to
cut in inside corners and to shape sharp, straight lines at
outside comers where walls intersect.
Afloat is glided over the surface of the plaster to fill
voids and hollows, to level bumps left by previous
operations, and to impart a texture to the surface. The
most common types of float are shown in figure 7-14.
The wood float has a wood blade 4 to 5 inches wide and
about 10 inches long. The angle float has a stainless steel
The darby (fig. 7-16) is, in effect, a float with an
extra long (3 1/2 to 4 foot) blade, equipped with handles
for two-handed manipulation. It is used for further
straightening of the base coat, after rodding is
rotor and stator assembly in the neck of the machine. A
machine of this type has a hopper capacity of from 3 to
5 cubic feet and can deliver from 0.5 to 2 cubic feet of
plaster per minute. On a piston-pump machine, a
hydraulic, air-operated, or mechanically operated piston
supplies the force for moving the wet plaster. On a
hand-hopper machine, the dry ingredients are placed in
a hand-held hopper just above the nozzle. Hopper
capacity is usually around 1/10 cubic foot. These
machines are mainly used for applying finish plaster.
Machine application reduces the use of the hawk
and trowel in initial plaster application. However, the
use of straightening and finishing hand tools remains
about the same for machine-applied plaster.
Figure 7-17.-Scarifier.
completed, to level plaster screeds and to level finish
coats. The blade of the darby is held nearly flat against
the plaster surface, and in such a way that the line of the
edge makes an angle 45° with the line of direction of the
A typical plastering crew for hand application
consists of a crew leader, two to four plasterers, and two
to four tenders. The plasterers, under the crew leader’s
supervision, set all levels and lines and apply and finish
the plaster. The tenders mix the plaster, deliver it to the
plasterers, construct scaffolds, handle materials, and do
cleanup tasks.
When a plaster surface is being leveled, the leveling
tool must move over the plaster smoothly. If the surface
is too dry, lubrication must be provided by moistening.
In base coat operations, dash or brush on water with a
water-carrying brush called a browning brush. This is a
fine-bristled brush about 4 to 5 inches wide and 2 inches
thick, with bristles about 6 inches long. For finish coat
operations, a finishing brush with softer, more pliable
bristles is used.
For a machine application, a typical crew consists
of a nozzle operator who applies the material, two or
three plasterers leveling and finishing, and two to three
The scarifier (fig. 7-17) is a raking tool that leaves
furrows approximately 1/8 inch deep, 1/8 inch wide, and
1/2 inch to 3/4 inch apart. The furrows are intended to
improve the bond between the scratch coat and the
brown coat.
Lack of uniformity in the thickness of a plaster coat
detracts from the structural performance of the plaster,
and the thinner the coat, the smaller the permissible
variation from uniformity. Specifications usually
require that plaster be finished “true and even, within
1/8-inch tolerance in 10 feet, without waves, cracks, or
imperfections.” The standard of 1/8 inch appears to be
the closest practical tolerance to which a plasterer can
work by the methods commonly in use.
Plastering Machines
There are two types of plastering machines: wet mix
and dry mix. The wet-mix pump type carries mixed
plaster from the mixing machine to a hose nozzle. The
dry-mix machine carries dry ingredients to a mixing
nozzle where water under pressure combines with the
mix and provides spraying force. Most plastering
machines are of the wet-mix pump variety.
The importance of adhering to the recommended
minimum thickness for the plaster cannot be overstressed. A plaster wall becomes more rigid as thickness
over the minimum recommended increases. As a result,
the tendency to crack increases as thickness increases.
However, tests have shown that a reduction of thickness
from a recommended minimum of 1/2 inch to 3/8 inch,
with certain plasters, decreases resistance by as much as
60 percent, while reduction to 1/4 inch decreases it as
much as 82 percent.
A wet-mix pump may be of the worm-drive,
piston-pump, or hand-hopper type. In a worm-drive
machine, mixed plaster is fed into a hopper and forced
through the hose to the nozzle by the screw action of a
be fog-sprayed cured for 48 hours. The finish coat
should not be applied for at least 7 days after the brown
coat. It too should be spray-cured for 48 hours.
The sequence of operations in three-coat gypsum
plastering is as follows:
1. Install the plaster base.
2. Attach the grounds.
Interior plaster can be finished by troweling,
floating, or spraying. Troweling makes a smooth finish;
floating or spraying makes a finish of a desired surface
3. Apply the scratch coat approximately 3/16 inch
4. Before the scratch coat sets, rake and cross
Smooth Finish
5. Allow the scratch coat to set firm and hard.
Finish plaster made of gypsum gauging plaster and
lime putty (called white coat or putty coat) is the most
widely used material for smooth finish coats. A putty
coat is usually applied by a team of two or more persons.
The steps are as follows:
6. Apply plaster screeds (if required).
7. Apply the brown coat to a depth of the screeds.
8. Using the screeds as guides, straighten the
surface with a rod.
1. One person applies plaster at the angles.
9. Fill in any hollows and rod again.
2. Another person follows immediately, straightening the angles with a rod or featheredge.
10. Level and compact the surface with a darby;
then rake and cross rake to receive the finish
3. The remaining surface is covered with a skim
coat of plaster. Pressure on the trowel must be
sufficient to force the material into the rough
surface of the base coat to ensure a good bond.
11. Define angles sharply with an angle float and a
featheredge. Trim back the plaster around the
grounds so the finish coat can be applied flush
with the grounds.
4. The surface is immediately doubled back to
bring the finish coat to final thickness.
5. All angles are floated, with additional plaster
added if required to fill hollows.
The steps for lime base coat work are similar to
those for gypsum work except that, for lime, an
additional floating is required the day after the brown
coat is applied. This extra floating is required to increase
the density of the slab and to fill in any cracks that may
have developed because of shrinkage of the plaster. A
wood float with one or two nails protruding 1/8 inch
from the sole (called a devil’s float) is used for this
6. The remaining surface is floated, and all hollows
filled. This operation is called drawing up. The
hollows being filled are called cat faces.
7. The surface is allowed to draw for a few minutes.
As the plaster begins to set, the surface-water
glaze disappears and the surface becomes dull.
At this point, troweling should begin. The
plasterer holds the water brush in one hand and
the trowel in the other, so troweling can be done
immediately after water is brushed on.
Portland Cement
8. Water is brushed on lightly, and the entire
surface is rapidly troweled with enough pressure
to compact the finish coat fully. The troweling
operation is repeated until the plaster has set.
Portland cement plaster is actually cement mortar.
It is usually applied in three coats, the steps being the
same as those described for gypsum plaster. Minimum
recommended thicknesses are usually 3/8 inch for the
scratch coat and brown coat, and 1/8 inch for the finish
The sequence of steps for trowel finishes for other
types of finish plasters is about the same. Gypsum-finish
plaster requires less troweling than white-coat plaster.
Regular Keene’s cement requires longer troweling, but
quick-setting Keene’s cement requires less. Preliminary
finishing of portland cement-sand is done with a wood
Portland cement plaster should be moist-cured,
similar to concrete. The best procedure is fog-spray
curing. The scratch coat and the brown coat should both
float, after which the steel trowel is used. To avoid
excessive drawing of fines to the surface, delay
troweling of the portland cement-sand as long as
possible. For the same reason, the surface must not be
troweled too long.
The steps in float finishing are about the same as
those described for trowel finishing except, of course,
that the final finish is obtained with the float. A surface
is usually floated twice: a rough floating with a wooden
float first, then a final floating with a rubber or carpet
float. With one hand the plasterer applies with the brush,
while moving the float in the other hand in a circular
motion immediately behind the brush.
Special Textures
Some special interior-finish textures are obtained
by methods other than or in addition to floating. A few
of these are listed beow.
Figure 7-18.—Masonry (two-coat work directly applied).
STIPPLED.— After the finish coat has been
applied, additional plaster is daubed over the surface
with a stippling brush or roller.
Stucco is a combination of cement or masonry
cement, sand and water, and frequently a plasticizing
material. Color pigments are often used in the finish
coat, which is usually a factory-prepared mix. The end
product has all the desirable properties of concrete.
Stucco is hard strong, fire resistant, weather resistant,
does not deteriorate after repeated wetting and drying,
resists rot and fungus, and retains colors.
The material used in a stucco mix should be free of
contaminants and unsound particles. Type I normal
Portland cement is generally used for stucco, although
type II, type III, and air-entraining may be used. The
plasticizing material added to the mix is hydrated lime.
Mixing water must be potable. The aggregate used in
cement stucco can greatly affect the quality and
performance of the finished product. It should be well
graded, clean, and free from loam, clay, or vegetable
matter, which can prevent the cement paste from
properly binding the aggregate particles together.
Follow the project specifications as to the type of
cement, lime, and aggregate to be used.
SPONGE.— By pressing a sponge against the
surface of the finish coat, you get a very soft, irregular
DASH.— The dash texture is obtained by throwing
plaster onto the surface from a brush. It produces a fairly
coarse finish that can be modified by brushing the
plaster with water before it sets.
TRAVERTINE.— The plaster is jabbed at random
with a whisk broom, wire brush, or other tool that will
form a dimpled surface. As the plaster begins to set, it
is troweled intermittentl y to form a pattern of rough and
smooth areas.
PEGGLE.— A rough finish, called peggle, is
obtained by throwing small pebbles or crushed stone
against a newly plastered surface. If necessary, a trowel
is used to press the stones lightly into the plaster.
this section, you should be able to identify the
composition of stucco, and state the procedures
for mixing, applying, and curing.
Metal reinforcement should be used whenever
stucco is applied on wood frame, steel frame, flashing,
masonry, or any surface not providing a good bond
Stucco may be applied directly on masonry.
The rough-floated base coat is approximately
3/8 inch thick. The finish coat is approximately 1/4 inch
thick. Both are shown in figure 7-18 applied to a
masonry surface. On open-frame construction
“Stucco” is the term applied to plaster whenever it
is applied to the exterior of a building or structure.
Stucco can be applied over wood frames or masonry
structures. A stucco finish lends warmth and interest to
open and sheathed frame construction requires three
coats of 3/8-inch scratch coat horizontally scored or
scratched, a 3/8-inch brown coat, and a 1/8-inch finish
Stucco is usually applied in three coats. The first
coat is the scratch coat; the second the brown coat; and
the final coat the finish coat. On masonry where no
reinforcement is used, two coats maybe sufficient. Start
at the top and work down the wall. This prevents mortar
from falling on the completed work. The first, or scratch,
coat should be pushed through the mesh to ensure the
metal reinforcement is completely embedded for
mechanical bond. The second, or brown, coat should be
applied as soon as the scratch coat has setup enough to
carry the weight of both coats (usually 4 or 5 hours). The
brown coat should be moist-cured for about 48 hours
and then allowed to dry for about 5 days. Just before the
application of the finish coat, the brown coat should be
uniformly dampened. The third, or finish, coat is
frequently pigmented to obtain decorative colors.
Although the colors may be job-mixed, a factoryprepared mix is recommended. The finish coat maybe
applied by hand or machine. Stucco finishes are
available in a variety of textures, patterns, and colors.
Figure 7-19.-Open-frame construction.
(fig. 7-19), nails are driven one-half their length into the
wood. Spacing should be 5 to 6 inches OC from the
bottom. Nails should be placed at all corners and
openings throughout the entire structure on the exterior.
The next step is to place wire on the nails. This is
called installing the line wire. Next, a layer of waterproof paper is applied over the line wire. Laps should be
3 to 4 inches and nailed with roofing nails. Install wire
mesh (stucco netting), which is used as the reinforcement for the stucco.
Furring nails (fig. 7-20) are used to hold the wire
away from the paper to a thickness of three- eighths of
an inch. Stucco or sheathed frame construction is the
same as open frame except no line wire is required. The
Surface Preparation
Before the various coats of stucco can be applied,
the surfaces have to be prepared. Roughen the surfaces
of masonry units enough to provide good mechanical
key, and clean off paint, oil, dust, soot, or any other
material that may prevent a tight bond. Joints may be
Figure 7-20.-Several types of furring nails.
struck off flush or slightly raked. Old walls softened and
disintegrated by weather action, surfaces that cannot be
cleaned thoroughly, such as painted brickwork, and all
masonry chimneys should be covered with galvanized
metal reinforcement before applying the stucco. When
masonry surfaces are not rough enough to provide good
mechanical key, one or more of the following actions
may be taken:
l Old cast-in-place concrete or other masonry may
be roughened with bush hammers or other
suitable hand tools. Roughen at least 70 percent
of the surface with the hammer marks uniformly
distributed. Wash the roughened surface free of
chips and dust. Let the wall dry thoroughly.
l Concrete surfaces may be roughened with an
acid wash. Use a solution of 1 part muriatic acid
to 6 parts water. Note: Add muriatic acid to the
water; never add water to the acid. First, wet
the wall so the acid will act on the surface only.
More than one application may be necessary.
After the acid treatment, wash the wall
thoroughly to remove all acid. Allow the washed
wall to dry thoroughly.
Figure 7-21.—Power-driven roughing machine.
When the masonry surface is not rough enough to
ensure an adequate bond for a trowel-applied scratch
coat, use the dash method. Acid-treated surfaces usually
require a dashed scratch coat. Dashing on the scratch
coat aids in getting a good bond by excluding air that
might get trapped behind a trowel-applied coat. Apply
the dash coat with a fiber brush or whisk broom, using
a strong whipping motion at right angles to the wall. A
cement gun or other machine that can apply the dash
coat with considerable force also produces a suitable
bond. Keep the dash coat damp for at least 2 days
immediately following its application and then allow it
to dry.
Protect the finish coat against exposure to sun and
wind for at least 6 days after application. During this
time, keep the stucco moist by frequent fog-spraying.
When your crew members are using
muriatic acid, make sure they wear
goggles, rubber gloves, and other
protective clothing and equipment.
l You can quickly rough masonry surfaces using a
power-driven roughing machine (such as that
shown in figure 7-21) equipped with a cylindrical
cage fitted with a series of hardened steel cutters.
The cutters should be mounted to provide a
flailing action that results in a scored pattern.
After roughing, wash the wall clean of all chips
and dust and let it dry.
Mixing procedures for stucco are similar to those
for plaster. Three things you need to consider before
mixing begins are the type of material you are going to
use, the backing to which the material will be applied,
and the method used to mix the material (hand or
machine). As with plaster, addition of too much of one
raw ingredient or the deletion of a raw material gives
you a bad mix. Prevent this by allowing only the
required amount of ingredients in the specified mix.
Suction is absolutely necessary to attain a proper
bond of stucco on concrete and masonry surfaces. It is
also necessary in first and second coats so the following
coats bond properly. Uniform suction also helps obtain
a uniform color. If one part of the wall draws more
moisture from the stucco than another, the finish coat
may be spotty. Obtain uniform suction by dampening
the wall evenly, but not soaking, before applying the
stucco. The same applies to the scratch and brown coats.
If the surface becomes dry in spots, dampen those areas
again to restore suction. Use a fog spray for dampening.
Stucco can be applied by hand or machine. Machine
application allows application of material over a large
area without joinings (joinings are a problem for
hand-applied finishes). To apply stucco, begin at the top
of the wall and work down. Make sure the crew has
sufficient personnel to finish the total wall surface
without joinings (laps or interruptions).
been made of ceramic tile for decorative effects
throughout buildings, both inside and outside.
Tile is usually classified by exposure (interior or
exterior) and location (walls or floors), although many
tiles may be used in all locations. Since exterior tile must
be frostproof, the tiles are kiln fired to a point where they
have a very low absorption. Tiles vary considerably in
quality among manufacturers. This may affect their use
in various exposures and locations.
The curing of stucco depends on the surface to
which it is applied, the thickness if the material, and the
weather. Admixtures can be used to increase
workability, prevent freezing, and to waterproof the
mortar. Using high-early cement reduces the curing time
required for the cement to reach its initial strength (3
days instead of 7). Air-entraining cement is used to resist
freezing action.
l Changes in materials or proportions during the
Tile is generally available in the following square
sizes: 4 1/4 by 4 1/4, 6 by 6, 3 by 3, and 1 3/8 by
1 3/8 inches. Rectangular sizes available include 8 1/2
by 4 1/4, 6 by 4 1/4, and 1 3/8 by 4 1/4 inches. Tile often
comes mounted into sheets (usually between 1 and
2 square feet) with some type of backing on the sheet or
between the tiles to hold them together.
Tiles with less than 6 square inches of face area and
about 1/4 inch thick are called ceramic mosaics.
Ceramic mosaic tile sizes range from 3/8 by 3/8 inch to
about 2 by 2 inches, and they are available from the
manufactures in both sheet and roll form. Often, large
tile is scored by the manufacturer to resemble small tiles.
l Variations in the amount of mixing water;
There are times when the finish you get is not what
you expected. Some of the most common reasons for
discoloration and stains are listed below:
l Failure to have uniform suction in either of the
base coats;
l Improper mixing of the finish coat materials;
l Use of additional water to retemper mortar; and
Tile finishes include glazed, unglazed, textured
(matte) glazed porcelain, and abrasive. Glazed and
matte glazed finishes may be used for light-duty floors
but should not be used in areas of heavy traffic where
the glazed surface may be worn away. Glazed ceramic
wall tiles usually have a natural clay body (nonvitreous,
7-to 9-percent absorption), and a vitreous glaze is fused
to the face of the tile. This type of tile is not
recommended for exterior use. Glazed tile should never
be cleaned with acid, which mars the finish. Use only
soap and water. Unglazed ceramic mosaics have dense,
nonvitreous bodies uniformly distributed through the
tile. Certain glazed mosaics are recommended for
interior use only, others for wall use only. Porcelain tiles
have a smoother surface than mosaics and are denser,
with an impervious body of less than one-half of
1-percent absorption. This type of tile may be used
throughout the interior and exterior of a building. An
abrasive finish is available as an aggregate embedded in
the surface or an irregular surface texture.
Tales are available with self-spacing lugs, square
edges, and cushioned edges (slightly rounded) (see
l Corrosion and rust from flashing or other metal
attachments and failure to provide drips and
washes on sills and projecting trim.
this section, you should be able to identify the
different types of ceramic tile and associated
mortars, adhesives, and grouts, and state the
procedures for setting tiles.
Ceramic tile is used extensively where sanitation,
stain resistance, ease in cleaning, and low maintenance
are desired. Ceramic tiles are commonly used for walls
and floors in bathrooms, laundry rooms, showers,
kitchens, laboratories, swimming pools, and locker
rooms. The tremendous range of colors, patterns, and
designs available in ceramic tile even includes
three-dimensional sculptured tiles. Extensive use has
Figure 7-22.—Tile edges.
Figure 7-23.—Trimmer shapes.
while the cement mortar is fresh and plastic. After
soaking in water for at least 30 minutes, the tiles are
installed over the neat cement bond coat. This type of
installation, with its thick mortar bed, permits wall and
floor surfaces to be sloped. This installation provides a
bond strength of 100 to 200 pounds per square inch. A
waterproof backing is sometimes required, and the
mortar must be damp-cured.
fig. 7-22). The lugs assure easy setting and uniform
joints. The edges available vary with the size of the tile
and the manufacturer.
Margins, comers, and base lines are finished with
trimmers of various shapes (fig. 7-23). A complete line
of shaped ceramic trim is available from manufacturers.
Other accessories include towel bars, shelf supports,
paper holders, grab rails, soap holders, tumbler holders,
and combination toothbrush and tumbler holders, to list
a few of the more popular units.
Dry-Set Mortar
Dry-set mortar is a thin-bed mortar of premixed
portland cement, sand, and admixtures that control the
setting (hardening) time of the mortar. It may be used
over concrete, block, brick, cellular foamed glass,
gypsum wallboard, and unpainted dry cement plaster, as
well as other surfaces. A sealer coat is often required
when the base is gypsum plaster. It is not recommended
for use over wood or wood products. Dry-set mortar can
be applied in one layer 3/32 inch thick, and it provides
a bond strength of 500 pounds per square inch. This
method has excellent water and impact resistance and
may be used on exteriors. The tiles do not have to be
presoaked, but the mortar must be damp-cured.
The resistance of ceramic tile to traffic depends
primarily on base and bonding material rigidity, grout
strength, hardness, and the accurate leveling and
smoothness of the individual tiles in the installation. The
four basic installation methods are cement mortar (the
only thick bed method), dry-set mortar, epoxy mortar,
and organic adhesives (mastic).
Cement Mortar
Cement mortar for setting ceramic tiles is composed
of a mixture of portland cement and sand. The mix
proportions for floors may vary from 1:3 to 1:6 by
volume. For walls, a portland cement, sand, and
hydrated lime mix may vary from 1:3:1 to 1:5 1/2:1.
These proportion ratios are dictated by the project
specifications. The mortar is placed on the surface 3/4
to 1 inch thick on walls and 3/4 inch to 1 1/4 inches thick
on floors. A neat cement bond coat is applied over it
Epoxy Mortar
Epoxy mortar can be applied in a bed as thin as 1/8
inch. When the epoxy resin and hardener are mixed on
the job, the resulting mixture hardens into an extremely
strong, dense setting bed. Pot life, once the parts are
mixed, is about 1 hour if the temperature is 82°F or
higher. This mortar has excellent resistance to the
Figure 7-24.-Special tile-setting tools.
texture than a plain cement. It maybe colored and used
in all areas subject to ordinary use. When the grout is
placed, the tiles should be wet. Moisture is required for
proper curing.
Drywall grout has the same characteristics as
dry-set mortar and is suitable for areas of ordinary use.
Tiles to be set in drywall grout do not require wetting
except during very dry conditions.
Epoxy grout consists of an epoxy resin and
hardener. It produces a joint that is stainproof, resistant
to chemicals, hard, smooth, impermeable, and easy to
clean. It is used extensively in counters that must be kept
sanitary for foods and chemicals. It has the same basic
characteristics as epoxy mortars.
Furan resin grout is used in industrial areas
requiring high resistance to acids and weak alkalies.
Special installation techniques are required with this
type of grouting.
Latex grout is used for a more flexible and less
permeable finish than cement grout. It is made by
introducing a latex additive into the Portland cement
grout mix.
corrosive conditions often encountered in industrial and
commercial installations. It may be applied over bases
of wood, plywood, concrete, or masonry. This type of
mortar is nonshrinking and nonporous. A bond strength
of over 1,000 pounds per square inch is obtained with
this installation method.
Organic Adhesives
Organic adhesives (mastics) are applied in a thin
layer with a notched trowel. They are solvent-base,
rubber material. Porous materials should be primed
before mastic is applied to prevent some of the
plasticizers and oils from soaking into the backing.
Suitable surfaces include wood, concrete, masonry,
gypsum wallboard, and plaster. The bond strength
available varies considerably among manufacturers, but
the average is about 100 pounds per square inch.
The joints between the tiles must be filled with a
grout selected to meet the tile requirements and
exposure. Tile grouts may be portland cement base,
epoxy base, furans, or latex.
Cement grout consists of portland cement and
admixtures. This is better in terms of waterproofing,
uniform color, whiteness, shrink resistance, and fine
A selection of special tools, shown in figure 7-24,
should be available when doing tile installation work.
A primary tool is a notched trowel with the notches
of the depth recommended by the adhesive
manufacturers. A trowel with notches on one side and
smooth on the other is preferred. Different sized trowels
are available.
A tile cutter is the most efficient tool for cutting
ceramic tile. The scribe on the cutter has a tungsten
carbide tip. A glass cutter can be used but quickly dulls.
Use tile nippers when trimming irregular shapes.
Nip off very small pieces of the tile you are cutting.
Attempting to take big chunks at one time can crack the
A rubber-surfaced trowel is used to force grout into
the joints of the tile.
There are three primary steps in tile installation:
applying a mortar bed, applying adhesive, and setting
tiles in place.
Before applying a mortar bed to a wall having
wooden studs, you first tack a layer of waterproof paper
to the studs. You then nail metal lath over the paper. The
first coat of mortar applied to a wall for setting tiles is a
scratch coat; the second is a float, leveling, or brown
A scratch coat for application as a foundation coat
must be at least 1/4 inch thick and composed of 1 part
cement to 3 parts sand, with the addition of 10-percent
hydrated lime by volume of the cement used. While still
plastic, the scratch coat is deeply scored or scratched and
cross scratched. Keep the scratch coat protected and
reasonably moist during the hydration period. All mortar
for scratch and float coats should be used within 1 hour
after mixing. Do not retemper partially hardened mortar.
Apply the scratch coat not more than 48 hours, nor less
than 24 hours, before setting the tile.
The float coat should be composed of 1 part cement,
1 part of hydrated lime, and 3 1/2 parts sand. It should
be brought flush with screeds or temporary guide strips,
placed to give a true and even surface at the proper
distance from the finished face of the tile.
Wall tiles should be thoroughly soaked for a
minimum of 30 minutes in clean water before being set.
Set tiles by troweling a skim coat of neat Portland
cement mortar on the float coat, or applying a skim coat
to the back of each tile unit and immediately floating the
tiles into place. Joints must be straight, level,
perpendicular, of even width, and not exceeding 1/16
inch. Wainscots are built of full courses. These may
extend to a greater or lesser height, but in no case more
than 1 1/2-inch from the specified or figured height.
Vertical joints must be maintained plumb for the entire
height of the tile work.
All joints in wall tile should be grouted full with a
plastic mix of neat white cement or commercial tile
grout immediately after a suitable area of the tile has
been set. Tool the joints slightly concave; cut off and
wipe excess mortar from the face of tiles. Any spaces,
crevices, cracks, or depressions in the mortar joints after
the grout has been cleaned from the surface should be
roughened at once and filled to the line of the cushioned
edge (if applicable) before the mortar begins to harden.
Tile bases or coves should be solidly backed with
mortar. Make all joints between wall tiles and plumbing
or other built-up fixtures with a light-colored caulking
compound. Immediately after the grout has set, apply a
protective coat of noncorrosive soap or other approved
protection to the tile wall surfaces.
The installation of wall tile over existing and
patched or new plaster surfaces in an existing building
is completed as previously described, except that an
adhesive is used as the bonding agent. Where wall tile
is to be installed in areas subject to intermittent or
continual wetting, prime the wall areas with adhesive
following the manufacturer’s recommendations.
Wall tiles may be installed either by floating or
buttering the adhesive. In floating, apply the adhesive
uniformly over the prepared wall surface using
quantities recommended by the manufacturer. Use a
notched trowel held at the proper angle to spread
adhesive to the required uniform thickness. Touch up
thin or bare spots with an additional coating of adhesive.
The area coated atone time should not be any larger than
that recommended by the manufacturer. In the buttering
method, daub the adhesive on the back of each tile. Use
enough so that, when compressed, the adhesive forms a
coating not less than 1/1 6 inch thick over 60 percent of
the back of each tile.
Laying Tile
The key to a professional-looking ceramic tile job
is to start working with a squared-off area. Most rooms
do not have perfectly square comers. As a result, the first
step is to mark off a square area in such a way that
fractional tiles at the comers (edges) are approximately
the same size. Begin by finding the lowest point of the
wall you are tiling. From this corner draw a horizontal
line one full tile height above the low point and extend
Figure 7-25.-Steps used for squaring a wall.
Figure 7-26.-Layout for installing ceramic wall tile.
4. Draw vertical lines B and C perpendicular to line
A (fig. 7-25). Apply tiles to the squared-off area
this line level across the entire width of the room. Refer
to the bathroom wall example in figure 7-25 as you study
the following steps:
first. Then cut and apply fractional tiles.
1. Find the low point of the tub.
Another method for figuring fractional tiles (edges)
is to employ the “half-tile rule.” (The stick method is
2. Measure up the height of one full tile at the low
point. Draw a horizontal line A. It must be level.
good for short walls, but the half-tile rule is needed for
long walls.) Take the number of full-size tiles required
3. Use a tile-measuring stick (fig. 7-26) to
determine the position of full-width tiles in such
away that fractional tiles at each comer or edge
are equal.
for one course, multiply this by the tile size, subtract this
answer from the wall length in inches, add one full tile
size and divide by 2. The result is the size of end tiles.
After determining fractional tiles, use a piece of
scrap wood from 36 inches to 48 inches in length to mark
up a tile-measuring stick (fig. 7-26, view A). Mark off
a series of lines equal to the width of a tile. Lay this stick
on the wall and shift it back and forth to determine the
starting point for laying the tiles. Make sure the
fractional tiles at the end of each row are of equal widths
(fig. 7-26, view B).
Use a level to establish a line perpendicular to the
horizontal starting line (fig. 7-26, view C). At both ends
of the horizontal line, draw vertical lines to form the
squared-off area. To make the tile application easier, you
can fasten battens to the wall on the outside of the drawn
Use a trowel to spread the mastic over approximately a 3- by 3-foot area of the wall. Use the notched
side to form ridges in the mastic, pressing hard against
the surface so that the ridges are the same height as the
notches on the tool. Allow the mastic to set for 24 hours
before applying grout. Follow the manufacturer’s
mixing instructions closely and use a rubber-surfaced
trowel to spread the grout over the tile surface. Work the
trowel in an arc, holding it at a slight angle so that grout
is forced into the spaces between the tiles.
Start tiling at either of the vertical lines and tile half
the wall at a time, working in horizontal rows. Press each
tile into the mastic, but do not slide them—the mastic
may be forced up the edges onto the tile surface. After
each course of tile is applied, check with the level before
spreading more mastic. If a line is crooked, remove all
tiles in that line and apply fresh ones. Do not use the
removed tiles until the mastic has been cleaned off.
Finish tiling the main area before fitting edge tiles.
When the grout begins to dry, wipe the excess from
the tiles with a damp rag. After the grout is thoroughly
dry, rinse the wall and wipe it with a clean towel.
Nonstaining caulking compound should be used at
all joints between built-in fixtures and tile work and at
the top of ceramic tile bases to ensure complete
waterproofing. Inside corners should be caulked before
a comer bead is applied.
Promptly replace cracked and broken tiles. This
protects the edges of adjacent tiles and helps maintain
waterproofing and appearance. Timely pointing of
displaced joint material and spalled areas in joints is
necessary to keep tiles in place.
A new tile surface should be cleaned according to
the tile manufacturer’s recommendations to avoid
damage to the glazed surfaces.
Although the following references
were current when this TRAMAN was
published, their continued currency
cannot be assured. You therefore need
to ensure that you are studying the
latest revisions.
Gypsum Construction Handbook, United States
Gypsum Company, Chicago, Ill., 1987.
Materials and Methods of Architectural Construction,
John Wiley & Sons, New York, 1958.
Plastering Skills, American Technical Publishers, Inc.,
Alsip, Ill., 1984.
The final stage of most construction projects is the
application of protective coatings, or “painting.” As
with all projects, you should follow the plans and
specifications for surface preparation and application
of the finish coat. The specifications give all the information you need to complete the tasks. But, to have a
better understanding of structural coatings, you need
to know their purposes, methods of surface preparation, and application techniques.
entering through neglected exterior surfaces. Porous
masonry is attacked and destroyed by moisture. Therefore, paint films must be as impervious to moisture as
possible to provide a protective, water-proof film over
the surface to which they are applied. Paint also acts
as a protective film against acids, alkalies, material
organisms, and other damaging elements.
Painting is an essential part of general maintenance programs for hospitals, kitchens, mess halls,
offices, warehouses, and living quarters. Paint
coatings provide smooth, nonabsorptive surfaces that
are easily washed and kept free of dirt and foodstuffs.
Adhering foodstuffs harbor germs and cause disease.
Coating rough or porous areas seals out dust and
grease that would otherwise be difficult to remove.
this section, you should be able to state the
purposes of the different types of structural
coatings and how each is employed.
The protection of surfaces is the most important
consideration in determining the maintenance cost
of structures. Structural coatings serve as protective
shields between the base construction materials and
elements that attack and deteriorate them. Regularly
programmed structural coatings offer long-range protection, extending the useful life of a structure.
personnel. In
picked up by
paints are used in these areas because
paint solvent odors are obnoxious to
food preparation areas, the odors maybe
nearby food.
Certain types of structural coatings delay the
spread of fire and assist in confining a fire to its area
of origin. Fire-retardant coatings should not be
considered substitutes for conventional paints. The
use of fire-retardant coatings is restricted to areas of
highly combustible surfaces, and must be justified and
governed by the specific agency’s criteria. Fireretardant coatings are not used in buildings containing
automatic sprinkler systems.
The primary purpose of a structural coating is
protection. This is provided initially with new construction and maintained by a sound and progressive
preventive maintenance program. Programmed painting enforces inspection and scheduling. A viable
preventive maintenance program will help ensure that
minor problems are detected at an early stage—before
they become major failures later. An added advantage
derived from preventive maintenance is the detection
of faulty structural conditions or problems caused by
leakage or moisture.
Camouflage paints have special properties,
making them different from conventional paints.
Their uses are limited to special applications. Do not
use camouflage paints as substitutes for conventional
paints. Use this paint only on exterior surfaces to
render buildings and structures inconspicuous by
blending them in with the surrounding environment.
Resistance to moisture from rain, snow, ice, and
condensation constitutes perhaps the greatest single
protective characteristic of paint, the most common
type of structural coating. Moisture causes metal to
corrode and wood to swell, warp, or rot. Interior
wall finishes of buildings can be ruined by moisture
PIGMENT.— Pigments are insoluble solids,
ground finely enough to remain suspended in the
vehicle for a considerable time after thorough stirring
or shaking. Opaque pigments give the paint its hiding,
or covering, capacity and contribute other properties
(white lead, zinc oxide, and titanium dioxide are
examples). Color pigments give the paint its color.
These may be inorganic, such as chrome green,
chrome yellow, and iron oxide, or organic, such as
toluidine red and phthalocyanine blue. Transparent or
extender pigments contribute bulk and also control the
application properties, durability, and resistance to
abrasion of the coating. There are other specialpurpose pigments, such as those enabling paint to
resist heat, control corrosion, or reflect light.
White and light-tinted coatings applied to ceilings
and walls reflect both natural and artificial light and
help brighten rooms and increase visibility. On the
other hand, darker colors reduce the amount of
reflected light. Flat coatings diffuse, soften, and
evenly distribute illumination, whereas gloss finishes
reflect more like mirrors and may create glare. Color
contrasts improve visibility of the painted surface,
especially when paint is applied in distinctive patterns.
For example, white on black, white on orange, or
yellow on black can be seen at greater distances than
single colors or other combinations of colors.
VEHICLES, OR BINDERS.— The vehicle, or
binder, of paint is the material holding the pigment
together and causing paint to adhere to a surface. In
general, paint durability is determined by the
resistance of the binder to the exposure conditions.
Linseed oil, once the most common binder, has been
replaced, mainly by the synthetic alkyd resins. These
result from the reaction of glycerol phthalate and an
oil and may be made with almost any property desired.
Other synthetic resins, used either by themselves or
mixed with oil, include phenolic resin, vinyl, epoxy,
urethane, polyester, and chlorinated rubber. Each has
its own advantages and disadvantages. When using
these materials, it is particularly important that you
exactly follow the manufacturers’ instructions.
Certain colors are used as standard means of
identifying objects and promoting safety. For
example, fire protection equipment is painted red.
Containers for kerosene, gasoline, solvents, and other
flammable liquids should be painted a brilliant yellow
and marked with large black letters to identify their
contents. The colors of signal lights and painted signs
help control traffic safely by providing directions and
other travel information.
this section, you should be able to identify the
types of structural coatings and finishes, and
the general characteristics of each.
purpose of a solvent, or thinner, is to adjust the
consistency of the material so that it can be applied
readily to the surface. The solvent then evaporates,
contributing nothing further to the film. For this
reason, the cheapest suitable solvent should be used.
This solvent is likely to be naphtha or mineral spirits.
Although turpentine is sometimes used, it contributes
little that other solvents do not and costs much more.
As a Builder, you must consider many factors
when selecting a coating for a particular job. One
important factor is the type of coating, which depends
on the composition and properties of the ingredients.
Paint is composed of various ingredients, such as
pigment, nonvolatile vehicle, or binder, and solvent,
or thinner. Other coatings may contain only a single
Synthetic resins usually require a special
solvent. It is important the correct one be used;
otherwise, the paint may be spoiled entirely.
In this section, we’ll cover the basic components
of paint—pigment, vehicles, and solvents—and
explain the characteristics of different types of paint.
Paint is composed of two basic ingredients:
pigment and a vehicle. A thinner may be added to
change the application characteristics of the liquid.
Paints, by far, comprise the largest family o f
structural coatings you will be using to finish
products, both interior and exterior. In the following
RUBBER-BASED.— Rubber-based paints are
solvent thinned and should not be confused with latex
binders (often called rubber-based emulsions).
Rubber-based paints are lacquer-type products and
dry rapidly to form finishes highly resistant to water
and mild chemicals. They are used for coating exterior
masonry and areas that are wet, humid, or subject to
frequent washing, such as laundry rooms, showers,
washrooms, and kitchens.
section, we’ll cover some of the most commonly
encountered types.
OIL-BASED PAINTS.— Oil-based paints
consist mainly of a drying oil (usually linseed) mixed
with one or more pigments. The pigments and
quantities of oil in oil paints are usually selected on
the basis of cost and their ability to impart to the paint
the desired properties, such as durability, economy,
and color. An oil-based paint is characterized by easy
application and slow drying. It normally chalks in such
a manner as to permit recoating without costly surface
preparation. Adding small amounts of varnish tends to
decrease the time it takes an oil-based paint to dry and
to increase the paint’s resistance to water. Oil-based
paints are not recommended for surfaces submerged
in water.
PORTLAND CEMENT.— Portland cement
mixed with several ingredients acts as a paint binder
when it reacts with water. The paints are supplied as a
powder to which the water is added before being used.
Cement paints are used on rough surfaces, such as
concrete, masonry, and stucco. They dry to form hard,
flat, porous films that permit water vapor to pass
through readily. When properly cured, cement paints
of good quality are quite durable. When improperly
cured, they chalk excessively on exposure and may
present problems in repainting.
ENAMEL.— Enamels are generally harder,
tougher, and more resistant to abrasion and moisture
penetration than oil-based paints. Enamels are
obtainable in flat, semigloss, and gloss. The extent of
pigmentation in the paint or enamel determines its
gloss. Generally, gloss is reduced by adding lower cost
pigments called extenders. Typical extenders are
calcium carbonate (whiting), magnesium silicate
(talc), aluminum silicate (clay), and silica. The level
of gloss depends on the ratio of pigment to binder.
ALUMINUM.— Aluminum paints are available
in two forms: ready mixed and ready to mix.
Ready-mixed aluminum paints are supplied in one
package and are ready for use after normal mixing.
They are made with vehicles that will retain metallic
brilliance after moderate periods of storage. They are
more convenient to use and allow for less error in
mixing than the ready-to-mix form.
EPOXY.— Epoxy paints area combined resin and
a polyamide hardener that are mixed before use. When
mixed, the two ingredients react to form the end
product. Epoxy paints have a limited working, or pot,
life, usually 1 working day. They are outstanding in
hardness, adhesion, and flexibility-plus, they resist
corrosion, abrasion, alkali, and solvents. The major
uses of epoxy paints are as tile-like glaze coatings for
concrete or masonry, and for structural steel in
corrosive environments. Epoxy paints tend to chalk on
exterior exposure; low-gloss levels and fading can be
anticipated. Otherwise, their durability is excellent.
Ready-to-mix aluminum paints are supplied in
two packages: one containing clear varnish and the
other, the required amount of aluminum paste (usually
two-thirds aluminum flake and one-third solvent).
You mix just before using by slowly adding the
varnish to the aluminum paste and stirring. Readyto-mix aluminum paints allow a wider choice of
vehicles and present less of a problem with storage
stability. A potential problem with aluminum paints is
moisture in the closed container. When present,
moisture may react with the aluminum flake to
form hydrogen gas that pressurizes the container.
Pressure can cause the container to bulge or even pop
the cover off the container. Check the containers of
ready-mixed paints for bulging. If they do, puncture
the covers carefully before opening to relieve the
pressure. Be sure to use dry containers when mixing
aluminum paints.
LATEX.— Latex paints contain a synthetic
chemical, called latex, dispersed in water. The kinds
of latex usually found in paints are styrene-butadiene
(so-called synthetic rubber), polyvinyl acetate (PVA
or vinyl), and acrylic. Latex paints differ from other
paints in that the vehicle is an emulsion of binder and
water. Being water-based, latex paints have the
advantage of being easy to apply. They dry through
evaporation of the water. Many latex paints have
excellent durability. This makes them particularly
useful for coating plaster and masonry surfaces.
Careful surface preparation is required for their use.
In contrast to paints, varnishes contain little or no
pigment and do not obscure the surface to which
applied. Usually a liquid, varnish dries to a hard,
largely on the purpose, the location, and the type of
wood being covered.
transparent coating when spread in a thin film over a
surface, affording protection and decoration.
Of the common types of varnishes, the most
important are the oils, including spar, flat, rubbing,
and color types. These are extensively used to finish
and refinish interior and exterior wood surfaces, such
as floors, furniture, and cabinets. Spar varnish is
intended for exterior use in normal or marine
environments, although its durability is limited. To
increase durability, exterior varnishes are especially
formulated to resist weathering.
this section, you should be able to describe the
procedures used in preparing surfaces for
The most essential part of any painting job is
proper surface preparation and repair. Each type of
surface requires specific cleaning procedures. Paint
will not adhere well, provide the protection necessary,
or have the desired appearance unless the surface is in
proper condition for painting. Exterior surface
preparation is especially important because hostile
environments can accelerate deterioration.
Varnishes produce a durable, elastic, and tough
surface that normally dries to a high-gloss finish and
does not easily mar. Often, a lower gloss may be
obtained by rubbing the surface with a very fine steel
wool. However, it is simpler to use a flat varnish with
the gloss reduced by adding transparent-flatting
pigments, such as certain synthetic silicas. These
pigments are dispersed in the varnish to produce a
clear finish that dries to a low gloss, but still does not
obscure the surface underneath (that is, you can still
see the grain of the wood).
As a Builder, you are most likely to paint three
types of metals: ferrous, nonferrous, and galvanized.
Improper protection of metals is likely to cause fatigue
in the metal itself and may result in costly repairs or
even replacement. Correct surface preparation, prior
to painting, is essential.
Shellac is purified lac formed into thin flakes and
widely used as a binder in varnishes, paints, and stains.
(Lac is a resinous substance secreted by certain
insects.) The vehicle is wood alcohol. The natural
color of shellac is orange, although it can be obtained
in white. Shellac is used extensively as a finishing
material and a sealant. Applied over knots in wood, it
prevents bleeding.
Cleaning ferrous metals, such as iron and steel,
involves the removal of oil, grease, previous coatings,
and dirt. Keep in mind that once you prepare a metal
surface for painting, it will start to rust immediately
unless you use a primer or pretreatment to protect the
The nonferrous metals are brass, bronze, copper,
tin, zinc, aluminum, nickel, and others not derived
from iron ore. Nonferrous metals are generally
cleaned with a solvent type of cleaner. After cleaning,
you should apply a primer coat or a pretreatment.
Lacquers may be clear or pigmented and can be
lusterless, semigloss, or glossy. Lacquers dry or
harden quickly, producing a firm oil- and waterresistant film. But many coats are required to achieve
adequate dry-film thickness. It generally costs more to
use lacquers than most paints.
Galvanized iron is one of the most difficult metals
to prime properly. The galvanizing process forms a
hard, dense surface that paint cannot penetrate. Too
often, galvanized surfaces are not prepared properly,
resulting in paint failure. Three steps must be taken to
develop a sound paint system.
Stains are obtainable in four different kinds: oil,
water, spirit, and chemical. Oil stains have an oil
vehicle; mineral spirits can be added to increase
penetration. Water stains are solutions of aniline dyes
and water. Spirit stains contain alcohol. Chemical
stains work by means of a chemical reaction when
dissolved by water. The type of stain to use depends
1. Wash the galvanized surface with a solvent to
remove grease, waxes, or silicones. Manufacturers sometimes apply these to resist “white
rust” that may form on galvanized sheets stored
clear water immediately after scrubbing. Work on
small areas not larger than 4 square feet. Wear rubber
gloves, a rubber apron, and goggles when mixing and
applying the acid solution. In mixing the acid, always
add acid to water. Do not add water to acid; this can
cause the mixture to explode. For a very heavy
deposit, the acid solution may be increased to 10
percent and allowed to remain on the surface for 5
minutes before it is scrubbed.
under humid conditions. Mineral spirits or acid
washes should definitely not be used at this
2. Etch the surface with a mild phosphoric acid
wash. Etching increases paint adhesion and
helps overcome the stress forces generated by
expansion and contraction of the galvanized
coating. After acid washing the surface, rinse it
with clean water and allow to dry. When using
acid, remember the situation can represent actual or potential danger to yourself and other
employees in the area. Continuous and automatic precautionary measures minimize safety
problems and improve both efficiency and
morale of the crew.
Repairing Defects
All defects in a concrete or masonry surface must
be repaired before painting. To repair a large crack,
cut the crack out to an inverted-V shape and plug it
with grout (a mixture of two or three parts of mortar
sand, one part of portland cement, and enough water
to make it putty-like in consistency). After the grout
sets, damp cure it by keeping it wet for 48 hours. If oil
paint is to be used, allow at least 90 days for
weathering before painting over a grout-filled crack.
3. Apply a specially formulated primer. Two basic
types of primer are in common use: zinc-bound
and cementitious-resin. The zinc-bound type is
used for normal exposure. Most types of finish
can be used over this type of primer. Latex
emulsion paints provide a satisfactory finish.
Oil-based products should not be used over cementitious-resin primers. A minimum of two
coats of finish is recommended over each type
of primer.
Whenever possible, allow new plaster to age at
least 30 days before painting if oil-based paint is being
applied. Latex paint can be applied after 48 hours,
although a 30-day wait is generally recommended.
Before painting, fill all holes and cracks with
spackling compound or patching plaster. Cut out the
material along the crack or hole in an inverted-V
shape. To avoid excessive absorption of water from
the patching material, wet the edges and bottom of the
crack or hole before applying the material. Fill the
opening to within 1/4 inch of the surface and allow the
material to set partially before bringing the level up
flush with the surface. After the material has
thoroughly set (depending on the type of filler used),
use fine sandpaper to smooth out the rough spots.
Plaster and wallboard should have a sealer or a prime
coat applied before painting. When working with old
work, remove all loose or scaling paint, sand lightly,
and wash off all dirt, oil, and stains. Allow the surface
to dry thoroughly before applying the new finish coat.
In Navy construction, concrete and masonry are
normally not painted unless painting is required for
damp-proofing. Cleaning concrete and masonry
involves the removal of dirt, mildew, and efflorescence (a white, powdery crystalline deposit that
often forms on concrete and masonry surfaces).
Dirt and Fungus
Dirt and fungus are removed by washing with a
solution of trisodium phosphate. The strength of the
solution may vary from 2 to 8 ounces per gallon of
water, depending upon the amount of dirt or mildew
on the surface. Immediately after washing, rinse off
all the trisodium phosphate with clear water. If using
oil paint, allow the surface to dry thoroughly before
Before being painted, a wood surface should be
closely inspected for loose boards, defective lumber,
protruding nail heads, and other defects or irregularities.
Loose boards should be nailed tight, defective lumber
should be replaced, and all nail heads should be countersunk.
A dirty wood surface is cleaned for painting
by sweeping, dusting, and washing with solvent or
soap and water. In washing wood, take care to avoid
For efflorescence, first remove as much of the
deposit as possible by dry brushing with a wire brush
or a stiff fiber brush. Next, wet the surface thoroughly
with clear water; then, scrub with a stiff brush dipped
in a 5-percent solution (by weight) of muriatic acid.
Allow the acid solution to remain on the surface about
3 minutes before scrubbing, but rinse thoroughly with
excessive wetting, which tends to raise the grain. Wash
a small area at a time, then rinse and dry it immediately.
Wood that is to receive a natural finish (meaning
not concealed by an opaque coating) may require
bleaching to a uniform or light color. To bleach, apply
a solution of 1 pound of oxalic acid to 1 gallon of hot
water. More than one application may be required. After
the solution has dried, smooth the surface with fine
Rough wood surfaces must be sanded smooth for
painting. Mechanical sanders are used for large areas,
hand sanding for small areas. For hand sanding, you
should wrap sandpaper around a rubber, wood, or metal
sanding block. For a very rough surface, start with a
coarse paper, about No. 2 or 2 1/2. Follow this with a
No, 1/2, No. 1, or No. 1 1/2. You should finish with
about a No. 2/0 grit. For fine work, such as furniture
sanding, you should finish with a freer grit.
Sap or resin in wood can stain through a coat, or
even several coats, of paint. Remove sap or resin by
scraping or sanding. Knots in resinous wood should be
treated with knot sealer.
Green lumber contains a considerable amount of
water, most of which must be removed before use. This
not only prevents shrinkage after installation, but prevents blistering, cracking, and loss of adhesion after
applied paint. Be sure all lumber used has been properly
dried and kept dry before painting.
Conditioners are often applied on masonry to seal
a chalky surface to improve adhesion of water-based
Table 8-1.—Treatments of Various Substrates
Remove hardened resin by scraping or sanding. Since
sealer is not intended as a prime coat, it should be used
only when necessary and applied only over the affected
area. When previous paint becomes discolored over
knots on pine lumber, the sealer should be applied over
the old paint before the new paint is applied.
topcoats. Sealers are used on wood to prevent resin
running or bleeding. Fillers are used to produce a
smooth finish on open-grained wood and rough masonry. Table 8-1 presents the satisfactory treatments of
the various surfaces.
Since water-thinned latex paints do not adhere well
to chalky masonry surfaces, an oil-based conditioner is
applied to the chalky substrate before latex paint is
applied. The entire surface should be vigorously wire
brushed by hand or power tools, then dusted to remove
all loose particles and chalk residue. The conditioner is
then brushed on freely to assure effective penetration
and allowed to dry. Conditioner is not intended for use
as a finish coat.
Fillers are used on porous wood, concrete, and
masonry to provide a smoother finish coat.
Wood fillers are used on open-grained hardwoods.
In general, hardwoods with pores larger than those
found in birch should be filled. Table 8-2 lists the
characteristics of various woods and which ones
require fillers. The table also contains notes on
finishing. Filling is done after staining. Stain should
be allowed to dry for 24 hours before the filler is
Sealers are applied to bare wood like coats of paint.
Freshly exuded resin, while still soft, may be scraped
off with a putty knife and the area cleaned with alcohol.
Table 8-2.-Characteristics of Wood
material removed) rough concrete, concrete block,
stucco, or other masonry surfaces. The purpose is to
fill the open pores in the surface, producing a fairly
smooth finish. If the voids on the surface are large, you
should apply two coats of filler, rather than one heavy
coat. This avoids mud cracking. Allow 1 to 2 hours
drying time between coats. Allow the final coat to dry
24 hours before painting.
applied. If staining is not warranted, natural
(uncolored) filler is applied directly to the bare wood.
The filler may be colored with some of the stain to
accentuate the grain pattern of the wood.
To apply, you first thin the filler with mineral
spirits to a creamy consistency, then liberally brush it
across the grain, followed by a light brushing along
the grain. Allow it to stand 5 to 10 minutes until most
of the thinner has evaporated. At this time, the finish
will have lost its glossy appearance. Before it has a
chance to set and harden, wipe the filler off across the
grain using burlap or other coarse cloth, rubbing the
filler into the pores of the wood while removing the
excess. Finish by stroking along the grain with clean
rags. All excess filler must be removed.
this section, you should be able to describe the
techniques used in mixing and applying paint.
Most paints used in the Navy are ready-mixed,
meaning the ingredients are already combined in the
proper proportions. When oil paint is left in storage
for long periods of time, the pigments settle to the
bottom. These must be remixed into the vehicle before
the paint is used. The paint is then strained, if
necessary. All paint should be placed in the paint shop
at least 24 hours before use. This is to bring the paint
to a temperature between 65°F and 85°F.
Knowing when to start wiping is important. Wipng
too soon pulls the filler out of the pores. Allowing the
filler to set too long makes it hard to wipe off. A simple
test for dryness consists of rubbing a finger across the
surface. If a ball is formed, it’s time to wipe. If the filler
slips under the pressure of the finger, it is still too wet
for wiping. Allow the filler to dry for 24 hours before
applying finish coats.
There are three main reasons to condition and mix
paint. First, you need to redisperse, or reblend, settled
pigment with the vehicle. Second, lumps, skins, or
other impediments to proper application need to be
Masonry fillers are applied by brush to bare and
previously prepared (all loose, powdery, flaking
Table 8-3.—Mixing Procedures
eliminated. And, third, the paint must be brought to its
proper application temperature.
appearance with no evidence of varicolored swirls at
the top. Neither should there be lumps of undispersed
solids or foreign matter. Figure 8-1 illustrates the basic
steps for boxing paint.
Paints should be mixed, or blended, in the paint
shop just before they are issued. Mixing procedures
vary among different types of paints. Regardless of the
procedure used, try not to overmix; this introduces too
much air into the mixture. Table 8-3 outlines the types
of equipment and remarks for various coatings.
Mixing is done by either a manual or mechanical
method. The latter is definitely preferred to ensure
maximum uniformity. Manual mixing is less efficient
than mechanical in terms of time, effort, and results.
It should be done only when absolutely necessary and
be limited to containers no larger than 1 gallon.
Nevertheless, it is possible to mix 1-gallon and
5-gallon containers by hand. To do so, first pour half
of the paint vehicle into a clean, empty container. Stir
the paint pigment that has settled to the bottom of the
container into the remaining paint vehicle. Continue
to stir the paint as you return the other half slowly to
its original container. Stir and pour the paint from can
to can. This process of mixing is called boxing paint.
The mixed paint must have a completely blended
There are only three primary true-pigmented
colors: red, blue, and yellow. Shades, tints, and hues
are derived by mixing these colors in various
proportions. Figure 8-2 shows a color triangle with
one primary color at each of its points. The lettering
Figure 8-2.—A color triangle.
Figure 8-1.—Manual mixing and boxing.
Skins should be removed from the paint before
mixing. If necessary, the next step is thinning. Finally,
the paint is strained through a fine sieve or commercial
paint strainer.
in the triangle indicates the hues that result when
colors are mixed.
A— Equal proportions of red and blue produce purple.
B— Equal proportions of red and yellow produce
Try not to tint paint. This will reduce waste and
eliminate the problem of matching special colors at a
later date. Tinting also affects the properties of the
paint, often reducing performances to some extent.
One exception is the tinting of an intermediate coat to
differentiate between that coat and a topcoat; this
helps assure you don’t miss any areas. In this case, use
only colorants of known compatibility. Try not to add
more than 4 ounces of tint per gallon of paint. If more
is added, the paint may not dry well or otherwise
perform poorly.
C— Equal proportions of blue and yellow produce
D— Three parts of red to one part of blue produce
E— Three parts of red to one part of yellow produce
reddish orange.
F— Three parts of blue to one part of red produce
G— Three parts of yellow to one part of red produce
yellowish orange.
When necessary, tinting should be done in the
paint shop by experienced personnel. The paint must
be at application viscosity before tinting. Colorants
must be compatible, fresh, and fluid to mix readily.
Mechanical agitation helps distribute the colorants
uniformly throughout the paint.
H— Three parts of blue to one part of yellow produce bluish green.
I— Three parts of yellow to one part of blue produce
yellowish green.
Hues are known as chromatic colors, whereas
black, white, and gray are achromatic (neutral colors).
Gray can be produced by mixing black and white in
different proportions.
The common methods of applying paint are
brushing, rolling, and spraying. The choice of method
is based on several factors, such as speed of
application, environment, type and amount of surface,
type of coating to be applied, desired appearance of
finish, and training and experience of painters.
Brushing is the slowest method, rolling is much faster,
and spraying is usually the fastest by far. Brushing is
ideal for small surfaces and odd shapes or for cutting
in corners and edges. Rolling and spraying are
efficient on large, flat surfaces. Spraying can also be
used for round or irregular shapes.
When received, paints should be ready for
application by brush or roller. Thinner can be added
for either method of application, but the supervisor or
inspector must give prior approval. Thinning is often
required for spray application. Unnecessary or
excessive thinning causes an inadequate thickness of
the applied coating and adversely affects coating
longevity and protective qualities. When necessary,
thinning is done by competent personnel using only
the thinning agents named by the specifications or
label instructions. Thinning is not done to make it
easier to brush or roll cold paint materials. They
should be preconditioned (warmed) to bring them up
to 65°F to 85°F.
Local surroundings may prohibit the spraying of
paint because of fire hazards or potential damage from
over-spraying (accidentally getting paint on adjacent
surfaces). When necessary, adjacent areas not to be
coated must be covered when spraying is performed.
This results in loss of time and, if extensive, may offset
the speed advantage of spraying.
Brushing may leave brush marks after the paint is
dry. Rolling leaves a stippled effect. Spraying yields
the smoothest finish, if done properly. Lacquer
products, such as vinyls, dry rapidly and should be
sprayed. Applying them by brush or roller may be
difficult, especially in warm weather or outdoors on
Normally, paint in freshly opened containers does
not require straining. But in cases where lumps, color
flecks, or foreign matter are evident, paints should be
strained after mixing. When paint is to be sprayed, it
must be strained to avoid clogging the spray gun.
breezy days. The painting method requiring the most
training is spraying. Rolling requires the least training.
LEARNING OBJECTIVE: Upon completing this
section, you should be able to identify the
common types of coating failures and recognize
the reasons for each.
A coating that prematurely reaches the end of its
useful life is said to have failed. Even protective coatings
properly selected and applied on well-prepared surfaces
gradually deteriorate and eventually fail. The speed of
deterioration under such conditions is less than when
improper painting procedures are earned out. Inspectors
and personnel responsible for maintenance painting must
recognize signs of deterioration to establish an effective
and efficient system of inspection and programmed
painting. Repainting at the proper time avoids the
problems resulting from painting either too soon or too
late. Applying coatings ahead of schedule is costly and
eventually results in a heavy buildup that tends to
quicken deterioration of the coating. Applying a coating
after it is scheduled results in costly surface preparation
and may be responsible for damage to the structure,
which may then require expensive repairs.
Figure 8-3.—Alligatoring.
In the following sections, we’ll look at some of the more
common types of paint failures, the reasons for such
failures, methods of prevention, and cures.
Paint failures can result from many causes. Here, we’ll
look at some of the most common caused by faults in
surface preparation.
Alligatoring (fig. 8-3) refers to a coating pattern that
looks like the hide of an alligator. It is caused by uneven
expansion and contraction of the undercoat. Alligatoring
can have several causes: applying an enamel over an oil
primer; painting over bituminous paint, asphalt, pitch, or
shellac; and painting over grease or wax.
Figure 8-4.—Peeling.
be sanded before painting. Also, the use of incompatible
paints can cause the loss of adhesion. The stresses in the
hardening film can then cause the two coatings to
separate and the topcoat to flake and peel.
Peeling (fig. 8-4) results from inadequate bonding of
the topcoat with the undercoat or the underlying surface.
It is nearly always caused by inadequate surface
preparation. A topcoat peels when applied to a wet, dirty,
oily or waxy, or glossy surface. All glossy surfaces must
Blistering is caused by the development of gas or liquid
pressure under the paint. Examples are shown
in figure 8-5. The root cause of most blistering, other
than that caused by excessive heat, is inadequate
ventilation plus some structural defect allowing
moisture to accumulate under the paint. A prime
source of this problem, therefore, is the use of
essentially porous major construction materials that
allow moisture to pass through. Insufficient drying
time between coats is another prime reason for
blistering. All blisters should be scraped off, the paint
edges feathered with sandpaper, and the bare places
primed before the blistered area is repainted.
One particular area you, as a Builder, have
direct control over is application. It takes a lot of
practice, but you should be able to eliminate the two
most common types of application defects: crawling
and wrinkling.
Crawling (fig. 8-6) is the failure of a new coat
of paint to wet and form a continuous film over the
preceding coat. This often happens when latex paint
is applied over high-gloss enamel or when paints are
applied on concrete or masonry treated with a
silicone water repellent.
Prolonged Tackiness
A coat of paint is dry when it ceases to be
“tacky” to the touch. Prolonged tackiness indicates
excessively slow drying. This may be caused by
insufficient drier in the paint, a low-quality vehicle in
the paint, applying the paint too thickly, painting
over an undercoat that is not thoroughly dry,
painting over a waxy, oily, or greasy surface, or
painting in damp weather.
When coatings are applied too thickly,
especially in cold weather, the surface of the coat
dries to a skin over a layer of undried paint
underneath. This usually causes wrinkling (fig. 8-7).
Wrinkling can be avoided in brush painting or roller
painting by brushing or rolling each coat of paint as
thinly as possible. In spray painting, you can avoid
wrinkling by keeping the gun in constant motion over
the surface whenever the trigger is down.
Inadequate Gloss
Sometimes a glossy paint fails to attain the
normal amount of gloss. This may be caused by
inadequate surface preparation, application over an
undercoat that is not thoroughly dry, or application
in cold or damp weather.
Not all painting defects are caused by the
individual doing the job. It sometimes happens that
the coating itself is at fault. Chalking, checking, and
cracking are the most common types of product
defects you will notice in your work as a Builder.
Figure 8-5.—Blistering.
Figure 8-6.-Crawling.
allowing continuous repainting without making the
coating too thick for satisfactory service.
Do not use a chalking or self-cleaning paint
above natural brick or other porous masonry surfaces.
The chalking will wash down and stain or discolor these
Chalked paints are generally easier to repaint
since the underlying paint is in good condition and
requires little surface preparation. But, this is not the
case with water-thinned paints; they adhere poorly to
chalky surfaces.
Checking and Cracking
Checking and cracking are breaks in a coating
formed as the paint becomes hard and brittle.
Temperature changes cause the substrate and overlying
paint to expand and contract. As the paint becomes
hard, it gradually loses its ability to expand without
breaking. Checking (fig. 8-9) consists of tiny breaks in
only the upper coat or coats of the paint film
Figure 8-7.—Wrinkling.
Chalking (fig. 8-8) is the result of paint
weathering at the surface of the coating. The vehicle is
broken down by sunlight and other destructive forces,
leaving behind loose, powdery pigment that can easily be
rubbed off with the finger. Chalking takes place rapidly
with soft paints, such as those based on linseed oil.
Chalking is most rapid in areas exposed to sunshine. In
the Northern Hemisphere, for example, chalking is most
rapid on the south side of a building. On the other hand,
little chalking takes place in areas protected from
sunshine and rain, such as under eaves or overhangs.
Controlled chalking can be an asset, especially in white
paints where it acts as a self-cleaning process and helps
to keep the surface clean and white. The gradual
wearing away reduces the thickness of the coating, thus
Figure 8-9.—Severe checking.
Figure 8-8.—Degrees of chalk.
without penetrating to the substrate. The pattern is
usually similar to that of a crow’s foot. Cracking is larger
with longer breaks extending through to the substrate
(fig. 8-10). Both result from stresses exceeding the
strength of the coating. But, whereas checking arises
from stress within the paint film, cracking is caused by
stresses between the film and the substrate.
increased by proper treatment and continued
maintenance. Wood defects are also caused by improper
care after preservation treatment. All surfaces of treated
wood that are cut or drilled to expose the untreated
interior must be treated with a wood preservative.
Cracking generally takes place to a greater extent
on wood, due to its grain, than on other substrates. The
stress in the coating is greatest across the grain, causing
cracks to form parallel to the grain of the wood.
Checking and cracking are aggravated by excessively
thick coatings that have reduced elasticity. Temperature
variations, humidity, and rainfall are also concerns for
checking or cracking.
There are two basic methods for treating wood:
pressure and nonpressure. Pressure treatment is
superior to nonpressure, but costly and time consuming.
Building specifications dictate which method to use.
The capacity of any wood to resist dry rot, termites,
and decay can be greatly increased by impregnating the
wood with a general-purpose wood preservative or
fungicide. It’s important to remember that good
pressure treatment adds to the service life of wood in
contact with damp ground. It does not, however,
guarantee the wood will remain serviceable throughout
the life of the building it supports.
this section, you should be able to describe how
to treat wood for protection against dry rot,
termites, and decay.
There are three destructive forces against which
most wood protective measures are directed: biological
deterioration (wood is attacked by a number of
organisms), fire, and physical damage. In this section,
we’ll deal with protecting wood products against
biological deterioration.
Woods of different timber species do not treat with
equal ease. Different woods have different capacities for
absorbing preservatives or other liquids. In any given
wood, sapwood is more absorbent than heartwood.
Hardwoods are, in general, less absorbent than
softwoods. Naturally, the extent to which a preservative
protects increases directly with the depth it penetrates
below the surface of the wood. As we just mentioned, the
best penetration is obtained by a pressure method. Table
8-4 shows the ease of preservative penetration into
various woods. In the table, use E for easy, M for
moderate, and D for difficult.
Damage to wood buildings and other structures by
termites, wood bores, and fungi is a needless waste. The
ability of wood to resist such damage can be greatly
Nonpressure methods of applying preservatives to a
surface include dipping, brushing, and spraying. Figure
8-11 shows how you can improvise long tanks for the
dipping method. Absorption is rapid at first, then much
slower. A rule of thumb holds that in 3 minutes wood
absorbs half the total amount of preservative it will
absorb in 2 hours. However, the extent of the
penetration depends upon the type of wood, its moisture
content, and the length of time it remains immersed.
Surface application by brush or spray is the least
satisfactory method of treating wood from the
Figure 8-10.-Severe cracking.
Table 8-4.—Preservative Penetration
Builder. The type of treatment or preservative depends
on the seventy of exposure and the desired life of the
end product.
Preservatives can be harmful to personnel if
improperly handled. When applying preservatives,
you should take the following precautions:
Avoid undue skin contact;
Avoid touching the face or rubbing the eyes
when handling pretreated material;
Avoid inhalation of toxic (poisonous) material;
Work only in a properly ventilated space and
use approved respirators; and
Figure 8-11.—Improvised tanks for dip treating lumber.
Wash with soap and water after contact.
standpoint of maximum penetration. However, it is
more or less unavoidable in the case of already
installed wood, as well as treated wood that has been
cut or drilled to expose the untreated interior.
this section, you should be able to state the
principal fire and health hazards associated
with painting operations.
Every painting assignment exposes Builders to
conditions and situations representing actual or
potential danger. Toxic and flammable materials,
Pentachlorophenol and creosote coal tar are likely
to be the only field-mixed preservatives used by the
harmful effects. Continued exposure to even small
amounts may cause the body to become sensitized;
subsequent contact, even in small amounts, may cause
an aggravated reaction. The poisons in paint are
definite threats to normally healthy individuals and
serious dangers to persons having chronic illnesses or
disorders. Nevertheless, health hazards can be avoided
by a common-sense approach of avoiding unnecessary
contact with toxic or skin-imitating materials.
pressurized equipment, ladders, scaffolding, and
rigging always make painting a hazardous job.
Hazards may also be inherent in the very nature of the
environment or result from ignorance or carelessness
by the painter.
The main causes of painting accidents are unsafe
working conditions or equipment, and careless
personnel. The proper setting up and dismantling of
equipment, the required safety checks, and the proper
care of equipment may require more time than is spent
using it. Nevertheless, safety measures must be taken.
As with all tasks the Builder undertakes, safety
must be a primary concern from the earliest planning
stages to the final cleanup. Shortcuts, from personnel
protection to equipment-related safety devices, should
not be permitted. Follow the project safety plan, and
consult all applicable safety manuals when involved
with any paint operation. Remember, work safe, stay
Certain general rules regarding fire and explosion
hazards apply to all situations. All paint materials
should have complete label instructions stipulating the
potential fire hazards and precautions to be taken.
Painters must be advised and reminded of the fire
hazards that exist under the particular conditions of
each job. They need to be aware of the dangers
involved and the need to work safely. Proper firefighting equipment must always be readily available
in the paint shop, spray room, and other work areas
where potential fire hazards exist. Electric wiring and
equipment installed or used in the paint shop,
including the storage room and spray room, must
conform to the applicable requirements of the
National Electrical Code (NEC) for hazardous areas.
Although the following references
were current when this TRAMAN was
published, their continued currency
cannot be assured. You therefore need
to ensure that you are studying the
latest revisions.
Paints and Protective Coatings, NAVFAC MO-110,
Departments of the Army, Navy, and Air Force,
Washington, D.C., 1991.
Many poisons, classified as toxic and skinirritating, are used in the manufacture of paint.
Although your body can withstand small quantities of
poisons for short periods, overexposure can have
Wood Preservation, NAVFAC MO-312, Department of
the Navy, Naval Facilities Engineering Command,
Washington, D.C., 1968.
jigs and templates for assembling parts of similar
trusses, frames, and so on, should also be evaluated.
Although Builders must be familiar with the layout
and erection procedures for both the 40- by 100-foot
and the 20- by 48-foot PEBs, we will use the 20- by
48-foot rigid-frame, straight-walled PEB as the model
for our discussion. This building is prefabricated and
shipped in compact crates ready for erection. Each
structure is shipped as a complete kit, including all
materials and an instruction manual. It is extremely
important to follow the manual; you can easily install a
part incorrectly.
The 20- by 48-foot rigid-frame building is designed
for erection with basic hand tools and a minimum
number of people. The instruction manual may suggest
the PEB can be erected by seven persons. For military
construction, though, two teams or work crews supervised by an E-6 are recommended. The building is
designed for erection on a floor system of piers, concrete blocks, or a concrete slab.
When completed, a single rigid-frame building is
easy to expand for additional space. Buildings can be
erected end to end, as in figure 9-1, or side by side “in
multiple.” As this type of building uses only bolted
connections, it can be disassembled easily, moved to a
new location, and re-erected without waste or damage.
The primary responsibility of the Seabees is the
construction of advanced bases during the early phases
of crises and other emergency situations. As Builders,
it is our job to move swiftly to hostility areas and build
temporary facilities and structures to support U.S. military operations. We are expected to react expediently.
The most widely used structure for expediency
and as a temporary facility is the preengineered
building. This chapter covers the process involved
with the erection of such buildings, as well as woodframe tents, latrines, and the process of embarkation.
this section, you should be able to explain the
principles and procedures involved in the
preparation and erection of preengineered
metal buildings.
The preengineered building (PEB) discussed here
is a commercially designed structure, fabricated by
civilian industry to conform to armed forces specifications. A preengineered structure offers an advantage in
that it is designed for erection in the shortest possible
time. Each PEB is shipped as a complete building kit.
All necessary materials and instructions for erection are
included. Preengineered structures are available from
various manufacturers.
The typical PEB is a 40- by 100-foot structure. The
20- by 48-foot PEB is a smaller version of the 40- by
100-foot PEB using the same erection principles. Layout and erection of either size PEB is normally assigned
to Builders.
Component Parts
The component parts of a prefabricated structure
are shipped knocked down (KD). A manufacturer’s
instruction manual accompanies each shipment. The
manual contains working drawings and detailed instructions on how the parts should be assembled. Directions vary with different types of structures, but there
are certain basic erection procedures that should be
followed in all cases.
A preplan of the erection procedures should be
made based on a study of the working drawings or
manufacturers’ instructions. Preplanning should include the establishment of the most logical and expeditious construction sequence. Consideration should be
given to the manpower, equipment, rigging, and tools
required. Everything necessary for erection should then
be procured. The advantages of constructing and using
Working Drawings
The working drawings show which items are not
prefabricated or included in the shipment. These must
be constructed in the field. Make plans in advance for
the procurement of necessary materials for these
items. Foundations, for example, are often designated
“to be constructed in the field.”
Figure 9-1.—Two 20- by 48-foot rigid-frame, preengineered buildings erected end to end.
the forms and carefully worked around the bolts so they
remain vertical and true.
While the foundation is being prepared, other crewmembers are assigned various kinds of preliminary
work. This work includes uncrating material and inventory, bolting up rigid-frame assemblies, assembling
door leaves, and glazing windows. When all preliminary work is properly completed, assembly and erection
of the entire building are quicker and you have fewer
All materials, except paneling, should be uncrated
and laid out in an orderly manner so parts can be easily
found. Don’t uncrate paneling until it is ready to install.
When the crates are opened, don’t damage the lumber;
you can use it for scaffolding, props, and sawhorses.
After the building foundation has been prepared,
and where practical, building materials should be
placed on the building site near the place where they
will be used. Girts, purlins, cave struts, and brace rods
should be equally divided along each side of the foundation. Panels and miscellaneous parts that will not be
used immediately should be placed on boards on each
side of the foundation and covered with tarpaulins or
In addition to the usual reasons for stressing the
importance of a square and level foundation, there is
another reason peculiar to the erection of a prefabricated structure. Prefabricated parts are designed
to fit together without forcing. If the foundation is
even slightly out of square or not perfectly level, many
of the parts will not fit together as designed.
Continuously check the alignment of the anchor bolts
prior to, during, and after concrete is poured.
A lot of preliminary work is necessary before the
erection of a PEB can begin. After the building site is
selected, prepare to pour the foundation and slab.
Before concrete for the foundation piers can be
poured, templates for the anchor bolts are placed on the
forms, and anchor bolts are inserted in the holes. The
threads of the bolts are greased and nuts are placed on
them to protect the threads from the concrete. After a
last-minute check to ensure all forms are level and the
anchor bolts are properly aligned, concrete is placed in
similar covering until needed. Parts making up the
rigid-frame assemblies should be laid out ready for
assembly and in position for raising.
Always exercise care when unloading materials.
Remember: Damaged parts can delay getting the job
done in the shortest possible time. To avoid damage,
lower the materials to the ground-don’t drop them.
Figure 9-2, view A, will help you identify the
various structural members of a PEB and their
locations. View B shows the placement of liner panels.
Each part serves a specific purpose and must be
installed in the proper location to ensure a sound
Figure 9-2.—Identification of the structural members (view A) and the liner panels (view B).
structure. Never omit any part called for on the
detailed erection drawings. Each of the members,
parts, and accessories is labeled by stencil; it is not
necessary to guess which part goes where. Refer to the
erection plans and find the particular members you
need as you work.
All miscellaneous parts should be centrally located.
High-strength steel bolts are used at rigid-frame
connections: roof-beam splice and roof beam to
column. These high-strength bolts are identified by a
Y stamped into the head, as shown in figure 9-3. All
high-strength steel bolts and nuts should be tightened
to give at least the required minimum bolt tension
values. The bolts may be tightened with a torque
wrench, an impact wrench, or an open-end wrench.
Lay out the column and roof beams for assembly, using crate lumber to block up the frames.
Erect the center frame first. Use the minimum
number of high-strength bolts to bring the
frame members together. Install the remaining
bobs to get the proper tightness.
Panels and other parts not used immediately
should be placed on boards and protected from
the environment and jobsite debris.
Exterior Assembly
When a PEB is not erected on a concrete slab, a
floor system by the same manufacturer should be used.
Read and follow the manufacturer’s instructions when
you are installing the floor system.
Use galvanized machine bolts to assemble the girt
and purlin clips to the frame. Keep in mind that the
end frames have girt and purlin clips on one side only.
The center frame has girt and purlin clips on each side
of the frame.
The cave girts should be attached to the cave
angles with 5/16-inch left-hand nuts and shoulder
bolts. An example is shown in figure 9-4. You will
need two cave angles for each cave girt. In fastening
these together, remember the short section of the cave
angle is always fastened to the left side of the cave girt.
The long section of the cave angle is fastened to the
right side of the eave girt.
After the floor system or concrete slab has been
prepared, the next step is to uncrate and lay out the
structural parts. Lay the parts out in the following
Parts making up the frame assembly should be
laid out, ready for assembly and in position for
Use 3/8- by 1-inch galvanized machine bolts to
attach the gable angle and doorjamb top clips to the
bottom flange of the end frame roof beams.
Girts, purlins, and base angles should be divided (equally) along each side of the foundation.
A-FRAME.— To erect the frame, place A-frame
props in position—one 8-foot frame at each side of the
building and a 10-foot frame in the center of the
End-wall parts should be divided equally between the two ends.
Figure 9-3.—High-strength steel bolt.
Figure 9-4.—Attaching eave angle to girt.
building (see fig. 9-5). Prop the frame on two sawhorses and attach tag lines to assist in raising the ridge.
Raise the frame and brace it up with the A-frames. The
end frames are erected in a similar manner, except that
they are held in position by installing purlins and girts.
BRACE RODS.— After all sidewall girts, cave
girts, and base angles have been installed, install the
brace rods. Look at figure 9-6. First, attach brace rod
clips to the floor. Then, insert the end of the brace rod
down through the hole in the sidewall girt. Connect
the top end through the cave girt and the cave girt clip.
Finally, connect the bottom end through the clip on
the floor.
As soon as the four brace rods are in position, use
them to plumb the building. To plumb the rigid frame,
tighten or loosen the rod nuts at the brace rod clips to
adjust the column to plumb condition. Don’t forget:
When you tighten one side, the other side must be
To make sure you are installing the end-wall members correctly, snap a chalk line across the building,
using one edge of the columns for positioning the line.
Mark the center of the building on this line. Then, drop
a plumb bob from the center of the joint of the roof
beams at the ridge, with the line over the same side of
the roof beam as the chalk line. Adjust the frame so
Figure 9-6.-Installing brace rods.
the plumb bob is directly over the center mark. Brace
the roof beam in this position until the roof panels are
in place.
EXTERIOR WALLS.— Uncrate exterior panels
and distribute them near where they will be used. First,
separate and place panels for each end wall. Place
full-length wall panels for each comer. Centrally
locate lower and upper sidewall panels and above and
below window panels, along each side of the building.
Place roof and ridge panels in stacks of eight each on
the floor. Make sure you fashion all joints properly.
Next, tighten all fasteners using metal-backed
neoprene washers with all roof fasteners and with all
shoulder bolts in the sidewalls. Then, properly apply
black mastic or sealant to all roof panel side laps and
end laps.
Start paneling the end wall at one comer and work
across to the other comer. Install the comer panel,
locating the bottom of the panel over the first two
shoulder bolts in the base angle. Use a level to plumb
this panel with the other shoulder bolts located at the
center of the corrugations. Locate the “below window
panel” over the base angle shoulder bolts, and impale
over the shoulder bolts. Remove the panel and reinstall
it so that it underlaps the first panel by pulling out on
the corrugated edge of the first panel.
Figure 9-5.-Frame erection with A-frame props.
one row ahead of the ridge panels (see fig. 9-8). Before
proceeding with the work, make sure you are applying
enough black mastic or sealant. Roof paneling should
continue in this order to ensure a weathertight joint at
the corner laps. However, you should check the
drawings for the location and installation of the smoke
stacks and ridge ventilation.
For installing paneling and windows, follow the
same general instructions as those given for the end
wall. However, be sure that the girts are in a straight
line before impaling panels onto shoulder bolts. It is
important to block the girts in a straight line with
crating lumber cut to the correct length. The drawings
should be checked for proper location of shoulder
bolts. The first shoulder bolt should be 12 inches from
the center of the column, then 12 inches on center
DOORS AND WINDOWS.— Doorjambs can be
hung anytime after the end-wall structural parts are
completed, But, they must be hung before installing the
interior lining. A helpful hint is to hang the doors before
installing the exterior end-wall paneling, This makes
adjustments on the door frame easier.
Hinges are factory-welded to the doorjamb, and the
entrance doors are supposed to swing to the inside of
the building. Remove the hinge leaf from the doorjamb
and attach it to the door with 1-inch No. 10 flathead
wood screws. Hang the door and make adjustments to
get the proper clearances at the top and sides of the door.
Install the lockset in the door and attach the faceplate to
the door with 3/4-inch No. 8 flathead wood screws.
Attach the strike plate to the doorjamb with 1/2-inch
No. 8 flathead machine screws.
Recheck the plumb of the center frame. Adjust the
brace rods to plumb if necessary. Check the drawings
for the location of base angles.
The upper wall panels must overlap the lower wall
panels for weathertightness. Remember to use
metal-backed neoprene washers and No. 10 hex nuts
on shoulder bolts. Use machine screws (1/4 by 3/4
inch) for panel-to-panel connections at side laps.
ROOF ASSEMBLIES.— Since the roof panels
are factory-punched for panel-to-purlin connection,
the purlins must be accurately aligned. Spacer boards
constructed from crating lumber can be used to align
purlins, as shown in figure 9-7. Move the spacer
boards ahead to the next bay as the paneling
progresses. Before you actually start paneling the roof,
place the spacer board over the shoulder bolts and
insert nails in the 5/16-inch holes in the ridge purlins.
Start roof paneling at one end of the building.
Place the panels so the holes in the corrugation lineup
with the shoulder bolts in the roof beam, cave angles,
and ridge purlins. Install one cave panel to each side
of the building. The cave panels should be installed
Figure 9-7.-Aligning purlins with spacer board.
Figure 9-8.-Installing ridge and eave panels.
Hinges are also factory-welded to screen doors,
which swing to the outside of the building. The
method used in hanging screen doors is similar to
hanging entrance doors. A spring, however, is needed
to hold the screen door closed.
Interior Assembly
Figure 9-9.-Installing hardboard.
After the exterior members have been erected,
work can begin on installing the interior assemblies.
These include the liner panels, furring, hardboard
flashing, and the trim.
LINER PANELS.— Installation of the liner panels
consists of installing furring strips, hardboard liner panels, and trim and battens. Various liner panel parts were
shown earlier in view B of figure 9-2.
To install end walls properly, precut the liner
panels according to the cutting diagrams. The hardboard must be installed with the smooth surface
exposed and with a 1/8-inch gap between panels to
allow for expansion (fig. 9-9). A scrap piece of hardboard or batten can be used as a shim or spacer to
maintain the proper gap.
BASE FURRING.— Nail the base furring to the
floor 3 inches from each end and 2 feet 8 inches OC,
with the inside edge 7 3/8 inches from the building
structural line. You can get a better of this by referring
to figure 9-10. When base furring is to be used on a
wood floor, use 8d box nails. Use 1 1/4-inch No. 9
concrete nails for a concrete floor. Drill the 2 by 2s
and girts with a 5/32-inch bit so furring can be attached
to the sidewall and cave girt with 2-inch panhead No.
10 sheet-metal screws. Attach the hardboard to the
furring strips with 1 1/4-inch aluminum shingle nails
on 4-inch centers at the sides and ends (see fig. 9-11).
Use 8-inch centers at the intermediate furring.
Figure 9-11.-Nailing pattern for attaching hardboard to
Figure 9-10.-Installing furring for the end-wall liners.
the top and bottom hardboard flashing, as shown in
figure 9-14. Insert the outside edge into the retaining
grooves in the window. Nail metal flashing angle and
hardboard to the horizontal furring with 4d aluminum
nails 1 foot 8 inches OC. Install side hard- board flashing and metal flashing angles using the same procedures
discussed above.
The installed ceiling furring should intersect sidewall furring. When all the ceiling furring has been
installed, the hardboard liner can be installed. Remember the 1/8-inch gap between panels. The smoke stack
assembly should be attached to the block- ing and
furring with 4d aluminum nails. Hand trim the hardboard flashing for the ends of the ventilator opening and
attach the metal ventilator flashing (see fig. 9- 15).
VERTICAL FURRING.— The vertical furring
(fig. 9- 12) should be installed immediately after the
base, corner, and gable furrings are in place. The
center line of the furring on each side of the window
should be in line with the center line of the end-wall
panel corrugations (shown in the inserts). After the
end-wall hardboard has been installed, attach side and
top flashing to the door. Attach flashing to the furring
with 4d aluminum nails and to the door frames with
1/2-inch No. 10 sheet-metal screws, as shown in figure
After installing the end-wall liner, install furring for
the sidewall and ceiling. Cut the base so the end just
clears the inside flange of the center-frame column.
Nail the furring in the same manner as the end walls.
TRIM.— Install the cave molding with the
beveled edge against the ceiling panels. Attach each
sidewall furring strip with 4d aluminum nails. Use
HARDBOARD FLASHING.— With the furring
in place, you can now install the hardboard liner. Install
Figure 9-12.-Placing furring for liners.
Figure 9-13.-Side and top flashing for the doors.
Figure 9-16.-Interior trim.
Figure 9-14.-Top and bottom hardboard flashing.
Figure 9-17.-Batten strip.
quarter-round molding to trim the ceiling to the end
wall, end wall to sidewall, and walls to floor. Use
metal ridge flashing, as shown in figure 9-16, to trim
the ridge of the ceiling liner. It can be attached to the
ceiling furrings with 4d aluminum nails. Check the
drawings to make sure you are installing it correctly.
Next, cut battens to the required length and attach
them to the furring with 4d aluminum nails, 8 inches
OC. An example of this is shown in figure 9-17.
Figure 9-15.-Metal ventilator flashing.
General Comments
Don’t be careless with bolts, nuts, and miscellaneous fasteners just because they are furnished in quantities greater than actual requirements.Be careful
when using these fasteners to prevent scattering them
on the ground. Each evening, empty your pockets of
fasteners and other small parts before leaving the
erection site.
It’s obvious but worth repeating: In disassembling
a building, be sure to clearly mark or number all parts.
You will then know where the parts go when reassembling the building.
An extra amount of mastic or sealant is also furnished with each PEB. Here too, reasonable care in
applying mastic to roof panels and roof accessories
ensures an adequate supply.
Crating lumber can be used to construct an entrance platform and stairs at each end of a PEB. Figure
9-18 shows one way this might be done.
Disassembly of a preengineered building should
not be difficult once you are familiar with the erection
procedures. Basically, it involves accurately marking
the parts and following some basic steps.
There are five main steps in disassembling a PEB:
1. Remove hardboard liner panels.
2. Remove windows, door leaves, and end wall.
3. Remove diagonal brace angles and sag rods.
4. Remove braces, girts, and purlins.
5. Let down frames.
Handling of the building components during disassembly is very important. You may have to reuse
these same components again at another location. As
you complete disassembly, protect those components
from damage. Any damaged components will have to
be replaced, and time might not be on your side.
this section, you should be able to identify the
characteristics of wood-frame tents, SEA huts,
and field-type latrines.
There are three basic types of wood-frame construction of concern to Builders: tents with wood
frames for support; SEA huts (developed in Southeast
Asia during the Vietnam war); and field latrines.
Figure 9-19 shows working drawings for framing
and flooring of a 16- by 32-foot wood-frame tent,
Tents of this type are used for temporary housing,
storage, showers, washrooms, latrines, and utility
spaces at an advanced base.
Tent floors consist of floor joists (16-foot lengths
of 2 by 4s) and sheathing (4- by 8-foot sheets of
1/2-inch plywood). The supports for the floor framing
are doubled 2 by 4 posts anchored on 2 by 12 by 12
mudsills. The wall-framing members are 2 by 4 studs,
spaced 4-feet OC. The roof-framing members are 2 by
4 rafters, spaced 4-feet OC. The plates (2 by 4s) and
the bracing members (1 by 6s) are fabricated in the
field. A representative floor-framing plan for a
Figure 9-18.-Crate platform.
Figure 9-19.—Framing and flooring plans for a 16- by 32-foot wood-frame tent.
field-type shower and a washroom is shown in figure 920.
Basically, all field structures are derived from the
16- by 32-foot wood-frame tent. However, if more tent
space is needed, a 40- by 100-foot model is available.
This tent is not difficult to assemble because it is put
together without a floor. It can be erected without a
strongback frame since it comes complete with ridge
pieces, poles, stakes, and line, and does not require
framing. But no matter how easy erection may seem,
always read and follow the instructions.
When the 16- by 32-foot wood-frame tent is
modified with a metal roof, extended rafters, and
screened-in areas, it is called a Southeast Asia (SEA)
hut. An example of the completed product is shown in
figure 9-21. The SEA hut was originally developed in
Vietnam for use in tropical areas by U.S. troops for
berthing; but, it can readily be adapted for any use in
any situation. It is also known as a strongback because
of the roof and sidewall materials.
The SEA hut is usually a standard prefabricated
unit, but the design can be easily changed to fit local
Figure 9-20.-Floor-framing plan.
Figure 9-21.—Completed SEA huts.
requirements, such as lengthening the floor or making
the roof higher. The standard prefabrication of a SEA
hut permits disassembly for movement to other locations when structures are needed rapidly. As with all
disassembly of buildings, ensure it is not damaged in
the process.
Temporary facilities for disposal of human waste
are one of the first things to be constructed at an advance
base. A number of field-type latrines are designed for
this purpose; a 16-by 32-foot wood-frame tent maybe
used to shelter the latrine.
Four Seat
Figure 9-23.-Latrine box collapsed for shipment.
A prefabricated four-seat latrine box is shown in
figure 9-22. It can be collapsed for shipment, as shown
in figure 9-23.
Figure 9-22.-Prefabricated four–seat latrine box.
Figure 9-24.-Plan view of eight-seat field-type latrine.
Figure 9-25.-Margin of oil-soaked earth around latrine boxes.
Eight Seat
Two 4-foot 6-inch trough-type urinals are
furnished with the eight-seat latrine. Each is mounted
in a frame constructed as shown in figure 9-26. A
2-inch urinal drainpipe leads from the downpipe on
each urinal to a 6- by 6-foot urinal seepage pit. The
seepage pit is constructed as shown in figure 9-27.
A plan view of an eight-seat field-type latrine is
shown in figure 9-24. Two four-seat boxes straddle a 3by 7-foot pit. After the pit is dug, but before the boxes
are placed, a 4-foot-wide margin around the pit is excavated to a depth of 6 inches, as shown in figure 9-25. A
layer of oil-soaked burlap is laid in this-excavation.
Then, the excavated earth is soaked with oil, replaced,
and tamped down to keep surface water out.
As indicated in figure 9-24, the eight-seat fieldtype latrine can be expanded to a 16-seat field-type
Figure 9-26.-Frame for urinal trough.
Figure 9-27.-Urinal seepage pit.
Figure 9-28.
Burnout Type
A complete plan view of a four-hole burnout fieldtype latrine is shown in figure 9-28. The waste goes into
removable barrels. The waste is then disposed of at
another location. This type of latrine is used at most
advanced or temporary bases. The burnout latrine is
kept in an orderly condition (daily) by the camp maintenance personnel or the assigned sanitation crew. It can
be easily maintained by spreading lime over the waste
material or using diesel fuel to bum the waste material.
Once wood frame facilities are completed and occupied by the tenants, maintenance becomes the major
priority. The life span of a facility is greatly increased
with proper maintenance. Even though the majority of
these buildings are temporary in nature, most cart be
dismantled and reassembled at another site. Establishment of a regularly scheduled maintenance program
ensures the buildings are in a consistent state of readiness.
this section, you should be able to identify the
components of, preparation procedures for and
procedures used in the erection of a K-span
The K-span building is a relatively new form of
construction in the Seabee community. The intended
uses of these buildings are as flexible as the SEA huts
discussed earlier. Training key personnel in the operation of the related equipment associated with the K-span
is essential. These same personnel, once trained, can
instruct other members of the crew in the safe erection
of a K-span. The following section gives you some, but
not all, of the key elements associated with K-span
construction. As with other equipment, always refer to
the manufacturers’ manuals.
The main component of the K-span system is the
trailer-mounted machinery shown in figure 9-29. This
Figure 9-29.-Trailer–mounted machinery.
figure shows the primary components of the trailer as
well as general operations. The key element is the
operator’s station at the rear of the trailer (shown in
fig. 9-30). The individual selected for this station must
be able to understand the machine operations and
manuals. From here, the operator controls all the
elements required to form the panels. The operator
must remain at the controls at all times. The forming
of the panels is a complex operation that becomes
easier with a thorough understanding of the manuals.
From the placement of the trailer on site, to the
completion of the curved panel, attention to detail is
As you operate the panel, you will be adjusting the
various machine-operating components. Make
adjustments for thickness, radius, and the curving
machine according to the manuals. Do not permit
short cuts in adjustments. Any deviations in
adjustments, or disregard for the instructions found in
the operating manuals, will leave you with a pile of
useless material and an inconsistent building.
figure 9-31 as a guide, consider the following items
when placing the machinery:
Maneuvering room for the towing of the trailer,
or leave it attached to vehicle (as shown at A);
Length of unit is 27 feet 8 inches long by 7 feet
4 inches wide (B);
Allow enough room for run-out stands to hold
straight panels. Stands have a net length of 9
feet 6 inches each (C);
Find point X: From center of curve, measure
distance equal to radius in line with front of
curved frame. From point X, scribe an arc equal
to radius. This arc will define path of curved
panel. Add 10 feet for run-out stands and legs
Storage area required to store coil stock and
access for equipment to load onto machine (E);
Direction curved panels must be carried after
being formed (F);
Level area required to lay panels on ground for
seaming. Building will not be consistent if panels are not straight when seaming (G); and
To avoid setup problems, preplanning of the site
layout is important. Uneven or sloped ground is not a
concern as long as the bed of the trailer aligns with the
general lay of the existing surface conditions. Using
Space required for crane operations (H).
Figure 9-30.-Rear of K-span trailer.
Figure 9-31.-Machinery placement calculations.
noted in figure 9-32, the cross pipes are not provided in
the kit. They are provided by the contractor.
With the foundation forms in place, and the
building panels welded to the attaching angle (fig. 9-33)
at 12 inches OC, you are ready to place the concrete.
When placing the concrete, remember it is extremely
important that it be well-vibrated. This helps eliminate
voids under all embedded items. As the concrete begins
to set, slope the top exterior portion of the concrete cap
about 5 inches (fig. 9-34) to allow water to drain away
from the building. The elevation and type of interior
floor are not relevant as long as the finish of the interior
floor is not higher than the top of the concrete cap.
The design of the foundation for a K-span building
depends on the building’s size, existing soil conditions,
and wind load. The foundations for the buildings are
simple and easy to construct. With the even distribution
of the load in a standard arch building, the size of the
continuous strip footing is smaller and more economical
than the foundations for conventional buildings.
The concrete forms and accessories provided are
sufficient to form the foundations for a building 100 feet
long by 50 feet wide. When a different configuration is
required, forms are available upon request from the
The actual footing construction is based, as all
project are, on the building plans and specifications. The
location of the forms, placement of steel, and the psi
(pounds per square inch) of the concrete are critical.
Since the building is welded to the angle in the footer
prior to the concrete placement, all aspects of the footer
construction must be thoroughly checked for alignment
and square. Once concrete is placed, there is no way to
correct mistakes.
As mentioned above, forms are provided for the
foundation. Using table 9-1 as a guide, figure 9-32 gives
you a simple foundation layout by parts designation. As
With the placement of the machinery and forming
of the building panels in progress, your next
considerations are the placement and the weight-lifting
capabilities of the crane. Check the crane’s weight-lifting
chart for its maximum weight capacity. This dictates the
number of panels you can safely lift at the operating
distance. As with all crane operations, attempting to lift
more than the rated capacity can cause the crane to turn
Table 9-1.-Concrete Forms Included in Kit
(Each set of forms is sufficient to erect a building 100 feet
long by 50 feet wide)
Side form panels, 1′ × 10′, 12-gauge steel
Transition panels, 1′ × 12′′, 12-gauge steel
Transition panels, 1′ × 28′′, 12-gauge steel
End- wall caps, 1′ × 15′′, 12-gauge steel
Side- wall caps, 1′ × 19′′, 12-gauge steel
Filler form, 1′ × 12′, 12-gauge steel
Sidewall inside stop, 1′ × 12′′, 12-gauge steel
End wall inside stop, 1′ × 12′′, 12-gauge steel
Stakes, 1/4′′ diameter, bar steel
All-thread rod, 1/2-13 × 18′′
Hex nuts, 1/2-13
Hex bolts, 1/8-16 × 1-1/2′′
Hex nuts, 3/8-16
Flat washers, 1/8′′ SAE
Corner angles, 2′′ × 2′′ × 12′′, steel angle
Figure 9-32.-Simple form assembly.
Figure 9-33.
Figure 9-34.-Concrete foundation.
Attaching the spreader bar (fig. 9-35) to the curved
formed panels is a critical step; failure to tightly clamp
the panel can cause the panels to slip and fall with
potential harm to personnel and damage to the panel.
With guide ropes attached (fig. 9-36) and personnel
manning these ropes, lift panels for placement. When
lifting, lift only as high as necessary, position two men
at each free end to guide in place, and remind
Figure 9-35.-Spreader bar attachment.
crewmembers to keep their feet from under the ends
of the arches. Never attempt lifting any sets of panels
in high winds.
Place the first set of panels on the attaching angle
of foundation and position so there will be room for
the end-wall panels. After positioning the first set of
panels, clamp them to the angle, plumb with guide
ropes, and secure the ropes to previously anchored
stakes. Detach the spreader bar and continue to place
panel sets. Seam each set to standing panels before
detaching spreader bar.
Figure 9-36.-Guide rope diagram.
After about 15 panels (3 sets) are in place, measure
the building length at both ends (just above forms) and
at the center of the arch. This measurement will seldom
be exactly one foot per panel (usually slightly more),
but should be equal for each panel. Adjust the ends to
equal the center measure. Panels are flexible enough to
adjust slightly. Check these measurements periodically
during building construction. Since exact building
lengths are difficult to predict, the end wall attaching
angle on the finishing end of building should not be put
in place until all panels are set.
After arches are in place, set the longest end-wall
panel in the form, plumb, and clamp it in place. Work
from the longest panel outward and be careful to
maintain plumb.
The K-span building system is similar to other types
of preengineered or prefabricated buildings in that
windows, doors, and roll-up doors can be installed only
when erection is completed. When insulation of the
building is required, insulation boards (usually 4 by 8
feet) may be of any semirigid material that can be bent
to match the radius of the building. The insulation is
installed using clips, as shown in figure 9-37.
When the integrity of the end-wall panels is
continuous from ground to roof line, the end walls
become self-supporting. The installation of windows
(fig. 9-38), and aluminum and wood doors (figs. 9-39
and 9-40, respectively), presents no problem since the
integrity of the of the wall system is not interrupted.
Figure 9-37.-Insulation.
Figure 9-38.-Aluminum window installation.
Figure 9-39.-Aluminum door installation.
Figure 9-40.-Wood door installation.
Figure 9-41.-Overhead door frame.
the tactical plan for landing and the scheme of
maneuvers ashore.
The installation of the overhead door (fig. 9-41) does
present a problem in that it does interrupt the integrity
of the wall system. This situation is quickly overcome
by the easily installed and adjustable (height and
width) door frame package that supports both the door
and end wall. This door frame package is offered by
the manufacturer.
Embarkation planning requires detailed
knowledge of the characteristics, capabilities, and
limitations of ships, aircraft, and amphibious vehicles,
and their relationships to the troops, supplies, and
equipment to be embarked. The planner must be
familiar with transport types of amphibious ships,
Military Sealift Command (MSC) ships, merchant
ships, and cargo aircraft. MSC ships and merchant
ships pose certain problems; basically, they are not
designed, equipped, or have a crew large enough for
amphibious operations. But, their use must be
anticipated. The additional requirements of hatch
crews, winchmen, cargo-handling equipment, cargo
nets, assault craft, and other facilities must be
provided by the user.
Keep in mind that the information provided in this
section on the K-span building is minimal. During the
actual construction of this building, you must consult
the manufacturer’s complete set of manuals.
this section, you should be able to identify the
procedures and techniques used in preparing
material for embarkation.
For a smooth, expedient mount-out, careful preplanning and organizing are required. Embarkation,
whether by air, land, sea, or any combinations thereof,
is an all-hands evolution. A successful move requires
100-percent support.
Whether by ship during amphibious operations or
by aircraft for assault force support operations, you
must observe certain principles to ensure proper
Flexibility is extremely important. Proper
embarkation depends to a large extent on the mutual
understanding of objectives and capabilities, and full
cooperation in planning and execution by both the unit
mobilizing and the organization providing the lift.
Whenever possible, early communication and
coordination between the two is extremely important.
First, embarkation plans must support the plan for
landing and the scheme of maneuvers ashore.
Personnel, equipment, and supplies must be loaded so
they can be unloaded at the time and in the sequence
required to support operations ashore.
Second, embarkation plans must provide for the
highest possible degree of unit self-sufficiency.
Troops should not be separated from their combat
equipment and supplies. Weapons crews should be
embarked on the same ship or aircraft with their
weapons; radio operators with their radios; and
equipment operators with their equipment. In
addition, each unit should embark with sufficient
combat supplies, such as ammunition, gasoline, and
radio batteries, to sustain its combat operations during
the initial period in the operational area. All personnel
should have sufficient water and rations to sustain
themselves for 24 hours.
Embarkation planning involves all measures
necessary to assure timely and effective out-loading
of the amphibious task force and portions thereof.
Planning for embarkation also applies to all unit
moves, regardless of the method used for movement.
These measures are determined by the availability of
transportation and the transportation requirements of
the unit moving. In amphibious embarkation, the
OPNAV level in the chain of command determines
overall shipping requirements and the embarkation
schedules. This enables subordinate units to prepare
detailed loading plans for individual ships. Planning
requires constant coordination between commanders
in the Navy and the Air Force; they must have a mutual
understanding of the problems of each support group.
However, in the final analysis, the embarkation plan
must support the tactical deployment plan of the unit.
In the case of an amphibious landing, it must support
Third, plans must provide for rapid unloading in
the objective area. This can be achieved by a balanced
distribution of equipment and supplies.
Fourth, and last, plans must provide for dispersion
of critical units and supplies among several ships or
aircraft. The danger of not doing so is obvious. If
critical units and supplies are not dispersed, loss of one
ship, or a relatively few ships or aircraft, could result
in a major loss of combat capability. Accomplishment
of the mission can be seriously jeopardized.
embarkation plan, prepared by the embarkation group
commander, establishes the formation for embarkation units and assigns shipping to each embarkation
unit. It contains the same information as the landing
force embarkation plan, but in much greater detail.
The group embarkation plan has attached to it or
included within the embarkation organization a shipping assignment table.
Team Planning
Effective embarkation planning by the embarkation team is dependent upon the early receipt of information from higher authority. Detailed planning
begins with the determination of team composition
and the assignment of shipping, The following information should be included in the team’s embarkation
UNIT EMBARKATION PLAN.— The unit embarkation plan prepared by the embarkation unit commander establishes the formation of embarkation
teams and assigns each embarkation team to a ship. It
contains, generally, the same information as the group
embarkation plan, but in greater detail. Attached to
the unit embarkation plan is the unit embarkation
organization and shipping assignment table. Naval
construction force (NCF) units embarking alone outside of the landing force, either by amphibious means
or by air, should prepare an embarkation plan incorporating all of the information necessary for proper
embarkation by the unit.
Designation of the team embarkation officer(s);
Preparation and submission of basic loading
forms by troop units of the embarkation team;
Preparation of the detailed loading plan;
Designation of the ship’s platoon, billeting,
messing, and duty officers during the period of
the embarkation;
Designation and movement of advance parties
and advance details to the embarkation area;
Establishment of liaison with the embarkation
control office in the embarkation area;
Standard boxing procedures are required to minimize shipping, packing, and repacking of allowance
items and to establish uniformity among the NCF
units. Present mobility requirements necessitate being
partially packed for redeployment at all times. The
best method of obtaining this state of readiness is to
use packing boxes for day-to-day storage and for
dispensing all types of battalion allowance items.
Each NCF unit must fabricate mount-out boxes
according to the Embarkation Manual, COMCBPAC/
COMCBLANTINST 3120.1, for all authorized allowance items within the unit’s TOA that can be boxed.
Existing boxes may be used if the color and marking
codes conform with standard box markings.
Preparation for the schedule for movement of
troops, vehicles, equipment, and supplies to the
embarkation area; and
Preparation of plans for the security of cargo in
the embarkation area.
Three basic embarkation plans are normally prepared by the various command levels within the landing force: the landing force embarkation plan, the
group embarkation plan, and the unit embarkation
Packing Lists
PLAN.— The landing force embarkation plan includes the organization for embarkation; supplies and
equipment to be embarked; embarkation points and
cargo assembly areas; control, movement and embarkation of personnel; and miscellaneous information.
The landing force embarkation plan contains information from which the embarkation group commander
prepares a more detailed plan.
Packing lists must be prepared for each box. One
copy is placed inside the box; one copy is mounted in
a protective packet on the outside of the box; one copy
is kept on file in the embarkation mount-out control
center; and, one copy is retained by the department to
which the supplies or equipment belong. Packing lists
must be sufficiently detailed to locate needed items
without having to open and search several boxes.
These stocks include oil, gasoline, lubricants, rations,
and ammunition, plus a full allowance of equipment.
During a contingency mount-out, all or part of these
pm-positioned stocks may be used. As part of the
planning phase, NCF units should check the plan to be
supported to determine the exact amount and types of
supplies to be embarked and the location of the
When constructing mount-out boxes, observe the
following considerations:
Screw nails (or flathead screws) and glue must
be used to assemble the boxes.
Covers must be bolted to tapped metal inserts,
as shown in COMCBPAC/COMCBLANTINST 3120.1, or an equivalent bolting method.
Box interiors may be compartmented to suit the
Gross weight of the boxes should be limited to
250 pounds each for easy handling without
material-handling equipment.
Although the following references
were current when this TRAMAN was
published, their continued currency
cannot be assured. You therefore need
to ensure that you are studying the
latest revisions.
Boxes must be fabricated of 3/4-inch exteriorgrade plywood, reinforced with 2 by 4 ends.
Special boxes for large items are authorized,
but should conform to the criteria set forth in
Automatic Building Machine Type K-Span Operating
Manual, MIC-120 ABM, M.I.C. Industries, Inc.
Naval Construction Force/Seabee Chief Petty Officer,
NAVEDTRA 10600, Naval Education and Training
Command, Pensacola, Fla., June 1989.
Metal comers or other protection may be installed to prevent shipping damage.
Pre-positioned Stocks and Supplies
Naval Construction Force/Seabee Petty Officer First
Class, NAVEDTRA 10601, Naval Education and
Training Command, Pensacola, Fla., December
Because of the mobile nature of the NCF, it is
necessary to pre-position certain supplies and equipment in anticipation of use in contingency mount-outs.
are the substructure, consisting of the supporting
members, and the superstructure, consisting of the
decking and the stringers on which the decking is laid.
Heavy construction includes structures made of
steel, timber, concrete, or a combination of these materials. Examples include trestles, timber piers, and
waterfront structures. The requirement for heavy construction today is not as important as in earlier years;
however, the need to understand this type of construction still remains.
The substructure of a timber trestle is a series of
transverse frameworks called bents. Trestle bents are
used on solid, dry ground, or in shallow water with a
solid bottom. Pile bents are used in soft or marshy
ground, or where the water is so deep or the current so
swift that the use of trestle bents is impossible. The
posts of a pile bent are bearing piles or vertical members driven into the ground.
In this chapter, we’ll examine the materials used
in building heavy structures. We’ll also discuss the
methods and techniques of heavy construction, including shoring and excavation. In addition, we’ll
look at the procedures used in maintaining the structures.
The following terms are common to timber trestle
this section, you should be able to identify the
parts of a trestle, and describe the procedures
for erecting bents and superstructures.
Abutment— The ground support at each of the
extreme ends of a trestle superstructure. Examples
are shown in figures 10-1 and 10-2.
A trestle is a braced framework of timbers, piles,
or steel members, It is typically built to carry a roadway across a depression, such as a gully, a canyon, or
the valley of a stream. The two main parts of a trestle
Bracing— The timbers used to brace a trestle bent,
called transverse bracing, or the timbers used to
brace bents to each other, called longitudinal
Figure 10-2.-Placing and leveling abutment footings and
abutment sill.
Figure 10-1.-Abutment sill and footing and abutment
bracing. Figure 10-3 shows both types for a
two-story trestle bent.
Cap— The uppermost transverse horizontal
structural member of a bent. It is laid across the tops
of the posts.
Decking— The structure laid on the girders to form
the roadway across the trestle, It consists of a lower
layer of timbers (flooring) and an upper layer of
timbers (treadway).
Footing— The supports placed under the sills. In
an all-timber trestle, the footings consist of a series
of short lengths of plank. Whenever possible,
however, the footings are made of concrete,
Girder— One of a series of longitudinal supports
for the deck, which is laid on the caps. Also called
a stringer,
Post— One of the vertical structural members.
Sill— The bottom transverse horizontal structural
member of a trestle bent, on which the posts are
anchored, or transverse horizontal member, which
supports the ends of the girders at an abutment.
Substructure— The supporting structure of braced
trestle bents, as distinguished from the superstructure.
Figure 10-3.-Two–story trestle bent.
Superstructure— The spanning structure of
girders and decking, as distinguished from the
Trestle Bent— A single-story bent or a multistory
bent and the support framework or substructure of
a trestle. The parts of a single-story bent are shown
in figure 10-4. A two-story bent is shown above in
figure 10-3.
After the center line of a trestle has been determined, the next step is to locate the abutment on each
bank at the desired or prescribed elevation. The abutments are then excavated to a depth equal to the combined depths of the decking and the stringers, less an
allowance for settlement. The abutment footings and
the abutment sills are then cut, placed, and leveled (as
in fig, 10-2).
The horizontal distance from an abutment sill to the
first bent and from one bent to the next is controlled by
the length of the girder stock. It is usually equal to the
length of the stock, minus about 2 feet for overlap.
Girder stock is usually in 14-foot lengths. The centerto-center horizontal distance between bents is usually
14 minus 2, or 12 feet.
To determine the locations of the seats for the trestle
bents and the heights of the bents (fig. 10-5), first stretch
a tape from the abutment along the center line. Use a
builder’s level or a line level to level the tape. Drop a
plumb bob from the 12-foot mark on the tape to the
ground. The position of the plumb bob on the ground
will be the location of the first bent. The vertical distance from the location of the bob to the horizontal tape,
Figure 10-4.-Components of a single-story trestle bent.
Finally, measure the diagonals to determine the
lengths of the transverse diagonal braces. Cut the
braces to length and spike, lag-screw, or bolt them to
the sills, caps, and posts. Transverse diagonal bracing
is usually made of 2 by 8 stock.
Trestle Bent Erection
After assembly, the trestle bent is moved to the
abutment, and set in place on the footings at the seat.
Carefully plumb the bent and temporarily brace it with
timbers running from the top of the bent to stakes driven
at the abutment. Lay the superstructure (girders and
decking) from the abutment out to the top of the first
bent. The second bent is then brought out to the end of
the superstructure and set in place. Plumb the second
bent and measure the diagonals to determine the lengths
of the longitudinal diagonal braces between the first and
second bents. Then, cut the braces and spike, lag-screw,
or bolt them in place.
The superstructure is then earned out to the
second bent, after which the third bent is brought to
the end of the superstructure. This procedure is
repeated, usually by parties working out from both
abutments, until the entire span is completed.
Figure 10-5.-Locating seats for trestle bents.
less the thickness of a footing, will be the height of the
first bent.
Next, stretch the tape from the location of the first
bent, level it as before, and again drop a plumb bob from
the 12-foot mark. The position of the plumb bob will be
the location of the section bent. The vertical distance
from the location of the bob to the horizontal tape, plus
the height of the first bent, less the thickness of the
footing, will be the height of the second bent.
Finally, stretch the tape from the location of the
second bent and proceed as before. The vertical
distance from the location of the bob to the horizontal
tape, plus the height of the second bent, less the
thickness of a footing, will be the height of the third
bent, and so on.
Timber girders are usually 10 by 16s, 14 feet long,
spaced 3 feet 3 1/2 inches on center (OC). Various
methods of fastening timber stringers to timber caps
are shown in figure 10-6, view A. Various methods of
fastening steel girders to timber caps are shown in view
B. This view also shows three ways of fastening a
When a trestle bent is laid out and constructed, the
length of the posts is equal to the height of the bent, less
the combined depths of the cap and sill. In a four-post
bent, the centers- of the two outside posts are located
from 1 to 2 1/2 feet inboard of the ends of the sill, and
the centers of the two inner posts are spaced equally
distant between the other two.
Sills, caps, and posts are commonly made of stock
that ranges in size from 12 by 12s to 14 by 16s. If a
sill or cap is not square in a cross section, the larger
dimension should be placed against the ends of the
posts. The usual length for a sill or cap is 2 feet more
than the width of the roadway on the trestle. The
minimum width for a single-lane trestle is 14 feet; for
a two-lane trestle, 18 feet.
Part of the terrain at an assembly site may be graded
flat and used as a framing yard, or a low platform may
be constructed for use as a framing platform. To assemble a bent, lay the posts out parallel and properly spaced,
and set the cap and sill in position against the ends. Bore
the holes for the driftpins through the cap and the sill
into the ends of the posts, and drive in the driftpins. Cut
a pair of 2- by 8- by 18-inch scabs for each joint and
then spike, lag-screw, or bolt the scabs to the joints.
Figure 10-6.-Methods of fastening timber stringers and steel
girders to timber caps.
timber-nailing anchorage for flooring to the top of a
steel girder.
Timber decking consists of two layers of 3-inch
planks. The lower layer, called the flooring, is laid at
right angles to the stringers and nailed with two 60d
spikes to each stringer crossing. The upper layer, called
the tread (fig. 10-7), is laid securely and nailed at a 90°
angle to the flooring.
Most of the flooring planks and all of the tread
planks are cut to lengths that will bring the ends of the
planks flush with the outer faces of the outside stringers.
However, at 5-foot intervals along the superstructure, a
flooring plank is left long enough to extend 2 feet 8
inches beyond the outer faces of the outside stringers,
The extension serves as support for the curb risers, the
curb, and the handrail posts, as shown in figure 10-7.
The curb risers consist of 3-foot lengths of 6 by 6
timbers, one of which is set in front of each handrail
post as shown. A continuous 2 by 6 handrail is nailed
to 4 by 4 handrail posts. Each handrail post is supported
by a 2 by 4 knee brace, as shown.
An end dam, such as that shown in figure 10-8, is
set at each end of the superstructure. This prevents the
approach of the road to the trestle from washing out
or eroding between the abutment and the girders.
Figure 10-8.-End dam.
A pile is a load-bearing member made of timber,
steel, concrete, or a combination of these materials. It
is usually forced into the ground to transfer the load
to underlying soil or rock layers when the surface soils
at a proposed site are too weak or compressible to
provide enough support.
Timber Bearing
Timber bearing piles are usually straight tree
trunks cut off above ground swell with the branches
closely trimmed and the bark removed. Occasionally,
sawed timbers may be used as bearing piles.
CHARACTERISTICS.— A good timber pile has
the following characteristics:
this section, you should be able to identify the
types of piles used in heavy construction and
state the procedures for constructing a timber
It is free of sharp bends, large or loose knots,
shakes, splits, and decay.
It is uniformly tapered from butt to tip.
The centers of the butt and tip are end points of
a straight line that lies within the body of the
The principal structural members in many
waterfront structures are piles. There are different
types of and uses for piles. The common terms used
with piles and pile driving are explained below.
Cross-section dimensions for timber piles should
be as follows:
Piles shorter than 40 feet, tip diameters between
8 and 11 inches, and butt diameters between 12
and 18 inches.
Piles longer than 40 feet, tip diameters between
6 and 8 inches, and butt diameters between 13
and 20 inches. The butt diameter must not be
greater than the distance between the pile leads.
piles can be damaged while being driven, particularly
under hard-driving conditions. To protect a pile against
damage, cut the butt of the pile squarely (so the pile
hammer will strike it evenly) and chamfer it. When a
Figure 10-7.-Details of superstructure of a timber trestle.
driving cap is used, the chamfered butt must fit the cap.
When a cap is not used, the top end of the pile is wrapped
with 10 or 12 turns of wire rope at a distance of about
one diameter below the head of the pile (fig, 10-9, views
A and B). When a hole is bored in the butt of the pile,
double wrappings are used (view C). The pile can also
be wrapped or clamped if the butt is crushed or split. As
an alternative to wrapping, two half-rings of 3/8-inch
steel are clamped around the butt (view D).
The tip of the pile is cut off perpendicular to its axis.
When driven into soft or moderately compressible soil,
the tip of the pile may be left unpointed. A blunt-end
pile provides a larger bearing surface than a pointed-end
pile when used as an end-bearing pile. When driven, a
blunt-end pile that strikes a root or small obstruction
may break through it.
Where soil is only slightly compressible and must
be displaced, the tip of the pile is usually sharpened to
the shape of an inverted truncated pyramid (fig. 10-9,
view A). The blunt end is about 4 to 6 inches square;
the length of the point is 1 1/2 to 2 times the diameter
of the pile at its foot. A crooked pile maybe pointed for
driving, as shown in view B.
For hard driving, steel shoes are used to protect
the pile tips. A manufactured shoe is shown in view
C, and an improvised steel shoe is shown in view D.
heavy loads or the foundations are expected to be used
over a long period of time. Steel is best suited for use
as bearing piles where piles must be driven under any
of the following conditions:
Piles are longer than 80 feet.
Column strength exceeds the compressive
strength of timber.
To reach bedrock for maximum bearing surface
through overlying layers of partially decomposed rock.
To penetrate layers of coarse gravel or soft rock,
such as coral.
To attain great depth of penetration for stability
(for example, driving piles in a rock-bedded,
swiftly flowing stream where timber piles cannot be driven deeply enough for stability).
One of the most common types of steel bearing
piles is the pipe pile. An open-end pipe pile is open at
the bottom. A closed-rid pipe pile is closed at the
bottom. Another common type of steel pile is the
H-type, often seen as HP. When driving HPs, a special
driving cap (shown in fig. 10-10) is used.
Steel Bearing
Steel ranks next to timber in importance,
especially where the construction must accommodate
Figure 10-10.-HP-bearing pile and special cap for driving
Figure 10-9.-Preparation of timber piles for driving.
A concrete bearing pile may be cast in-place or
precast. A cast-in-place concrete pile may be a shell
type or a shell-less type.
A shell type of cast-in-place pile is constructed as
shown in figure 10-11. A steel core, called a mandrel,
is used to drive a hollow steel shell into the ground.
The mandrel is then withdrawn, and the shell is filled
with concrete. If the shell is strong enough, it may be
driven without a mandrel.
A shell-less cast-in-place concrete pile is made by
placing the concrete in direct contact with the earth.
The hole for the pile may be made by driving a shell
or a mandrel and shell, or it may be simply bored with
an earth auger. If a mandrel and shell are used, the
mandrel, and usually also the shell, are removed
before the concrete is poured. In one method, however, a cylindrical mandrel and shell are used, and only
the mandrel is removed before the concrete is poured.
The concrete is poured into the shell, after which the
shell is extracted. This sequence of events is shown in
figure 10-12.
Figure 10-12.-Procedure for cast-in-ground concrete piles.
piles run from 6 to 24 inches square. Concrete piles
more than 100 feet long can be cast, but are usually
too heavy for handling without special equipment.
Casting in place is not usually feasible for
concrete piles used in waterfront structures. Concrete
piles for waterfront structures are usually precast. The
cross section of precast concrete piles is usually either
square or octagonal (eight-sided). Square-section
Sheet piles are special shapes of interlocking piles
made of steel, wood, or formed concrete. They are
widely used to form a continuous wall to resist
horizontal pressures resulting from earth or water
loads. Examples include retaining walls, cutoff walls,
trench sheathing, cofferdams, and bulkheads in
wharves, docks, or other waterfront structures.
Cofferdams exclude water and earth from an
excavation so that construction can proceed easily.
Cutoff walls are built beneath water-retaining
structures to retard the flow of water through the
Sheet piles may also be used in the construction
of piers for bridges and left in place, Here, steel piles
are driven to form a square or rectangular enclosure,
The material inside is then excavated to the desired
depth and replaced with concrete.
Timber Pier Piles
Working drawings for advanced base timber
piers are contained in Facilities Planning Guide,
Volume I, NAVFAC P-437. Figure 10-13 shows
a general plan; figure 10-14, a part plan; and
Figure 10-11.-Shell type cast-in-place concrete pile.
Figure 10-13.-General plan of an advanced base 40-foot-timber pier.
Figure 10-14.-Part plan of an advanced base timber pier.
The cross section (fig. 10- 15) shows that each bent
consists of six bearing piles. The bearing piles are
braced transversely by diagonal braces. Additional
transverse bracing for each bent is provided by a pair
of batter piles. The batter angle is specified as 5 in 12.
One pile of each pair is driven on either side of the
bent, as shown in the general plan. The butts of the
batter piles are joined to 12-inch by 12-inch by 14-foot
longitudinal batter-pile caps. Each of these is bolted
to the undersides of two adjacent bearing-pile caps
with bolts in the positions shown in the part plan (fig.
10- 14). The batter-pile caps are placed 3 feet inboard
of the center lines of the outside bearing piles in the
bent. They are backed by 6- by 14-inch batter-pile cap
blocks, each of which is bolted to a bearing-pile cap.
Longitudinal bracing between bents consists of
14-foot lengths of 3 by 10 planks, bolted to the bearing
figure 10-15, a cross section for a 40-foot pier.
The drawings (examples are shown in figs. 10-13,
10-14, and 10-15) include a bill of materials, showing
the dimensions and location of all structural members,
driftpins, bolts, and hardware. Figures 10-13
and 10-14 are parts of NAVFAC Drawing No.
6028173; figure 10-15 is a part off NAVFAC Drawing
The size of the pier is designated by its width. The
width is equal to the length of a bearing-pile cap.
Each part of a pier lying between adjacent pile
bents is called a bay, and the length of a bay is equal
to the OC spacing of the bents. The general plan (fig.
10- 13) shows that the advanced base 40-foot timber
pier consists of one 13-foot outboard bay, one 13-foot
inboard bay, and as many 12-foot interior bays as
needed to meet requirements.
Figure 10-15.-Cross section of an advanced base timber pier.
Lengths of 8 by 10 fender pile chocks are cut to fit
between the piles and bolted to the outside stringers
and the fender wales. The spacing for these bolts is
shown in the part plan. As indicated in the general
plan, the fender system also includes two 14-pile
dolphins, located 15 feet beyond the end of the pier.
A dolphin is an isolated cluster of piles, constructed
as shown in figure 10-16. A similar cluster attached to
a pier is called a pile cluster.
The superstructure (fig. 10-15) consists of a single
layer of 4 by 12 planks laid on 19 inside stringers
measuring 6 inches by 14 inches by 14 feet. The inside
stringers are fastened to the pile caps with driftbolts.
The outside stringers are fastened to the pile caps with
through-bolts. The deck planks are fastened to the
stringers with 3/8- by 8-inch spikes. After the deck is
laid, 12-foot lengths of 8 by 10s are laid over the
outside stringers to form the curbing. The lengths of
curbing are distributed as shown in the general plan.
The curbing is bolted to the outside stringers to form
the curbing. The lengths of curbing are distributed as
shown in the general plan. The curbing is bolted to the
outside stringers with bolts.
When driving piles of any type, always watch both
the pile and equipment. Care must be taken to avoid
damaging the pile or the driving hammer. Watch the
piles carefully for any indications of splitting or
breaking below ground. The next section covers some
of the more common problems you might encounter.
The pier is equipped with a fender system for
protection against shock, caused by contact with
vessels coming or lying alongside. Fender piles,
spaced as shown in the part plan, are driven along both
sides of the pier and bolted to the outside stringers with
bolts. The heads of these bolts are countersunk below
the surfaces of the piles. An 8 by 10 fender wale is
bolted to the backs of the fender piles with bolts.
Springing and Bouncing
Springing means that the pile vibrates too much
laterally. Springing may occur when a pile is crooked,
when the butt has not been squared off properly, or
Figure 10-16.-Dolphins.
when the pile is not in line with the fall of the hammer.
Always make sure the fall of the hammer is in line with
the pile axis. Otherwise, the head of the pile and the
hammer may be severely damaged and much of the
energy of the hammer blow lost.
Excessive bouncing may be caused by a hammer
that is too light. However, it usually occurs when the
butt of the pile becomes crushed or broomed, as when
the pile meets an obstruction or penetrates to a solid
footing. When a double-acting hammer is being used,
bouncing may result from too much steam or air pressure. With a closed-end diesel hammer, if the hammer
lifts on the upstroke of the ram piston, the throttle setting
is probably too high. Back off on the throttle control just
enough to avoid this lifting. If the butt of the timber pile
has been crushed or broomed more than an inch or so,
it should be cut back to sound wood before you drive it
any more.
Obstruction and Refusal
When a pile reaches a level where 6 blows of a drop
hammer or 20 blows of a steam or air hammer do not
drive it more than an average of 1/8 inch per blow, the
pile has either hit an obstruction or has been driven to
refusal. In either case, further driving is likely to break
or split the pile. Examples of typical damage are shown
if figure 10-17.
If the lack of penetration seems to be caused by an
obstruction, 10 or 15 blows of less than maximum force
may be tried. This may cause the pile to displace or
penetrate the obstruction. For obstructions that cannot
be disposed of in this manner, it is often necessary to
pull (extract) the pile and clear the obstruction.
When a pile has been driven to a depth where deeper
penetration is prevented by friction, the pile has been
driven to refusal. It is not always necessary to drive a
friction pile to refusal. Such a pile needs to be driven
only to the depth where friction develops the required
load-bearing capacity.
Piles should be straightened when any misalignment is noticed during driving. The accuracy of
Figure 10-17.-Types of pile damage caused by overdriving
timber piles.
Figure 10-18.-Realigning pile by pull on a line to a winch.
alignment desirable for a finished job depends on various factors. Generally, though, a pile more than a few
inches out of its plumb line should be trued. The greater
the penetration along the wrong line, the harder to get
the pile back into plumb. There are several methods of
realigning a pile.
One method of realignment is to use pull from a
block and tackle, with the impact of the hammer jarring
the pile back into line (fig. 10-18). The straightening of
steel bearing piles must include twisting the individual
piles to bring the webs of the piles parallel to the center
line of the bent.
Another method of realignment is to use a jet (fig.
10-19), either alone or with either of the other two
methods. Jetting a pile can be done with either water or
When all piles in a bent have been driven, they can
be pulled into proper spacing and alignment with a
block and tackle and an aligning frame, as shown in
figures 10-20 and 10-21.
Figure 10-20.-Aligning framing used for timber pile bent.
A pile that has hit an obstruction, has been driven
in the wrong place, has been split or broken in driving,
or is to be salvaged (steel sheet piles are frequently
salvaged for reuse) is usually pulled (extracted).
Pulling should be done as soon as possible after
driving. The longer the pile stays in the soil, the more
compact the soil becomes, and the greater the
resistance to pulling will be.
Figure 10-21.-Aligning and capping steel pile bents.
this section, you should be able to describe the
uses of and construction methods for offshore,
alongshore, wharfage, and below the water
table construction.
Waterfront structures are broadly divided into three
main categories: offshore structures creating a sheltered
harbor; alongshore structures establishing and maintaining a stable shoreline; and wharfage structures
allowing vessels to lie alongside for loading or unloading.
Figure 10-19.-Realigning pile by jetting.
Offshore structures include breakwaters and
jetties. They are alike in construction and differ
mainly in function.
Breakwaters and Jetties
In an offshore barrier, the breakwater interrupts
the action of the waves of open water to create an area
of calm water between it and the shore. A jetty works
to direct and confine a current or tidal flow into a
selected channel.
The simplest type of breakwater or jetty is the
rubble mound (also called rock mound). An example
is shown in figure 10-22. The width of its cap may vary
from 15 to 70 feet. The width of its base depends on
the width of the cap, height of the structure, and slope
of the inner and outer faces.
Figure 10-24.-Caisson breakwater/jetty.
Rubble-mound breakwaters or jetties are
constructed by dumping rock from either barges or
railcars (running on temporary pile-bent structures)
and by placing upper rock and cap rock with floating
Figure 10-22.-Rubble-mound breakwater/jetty.
Figure 10-23.-Composite breakwater/jetty.
For a deepwater site or one with an extreme
range between high and low tides, a rubble-mound
breakwater or jetty may by topped with a cap structure to form the composite type shown in figure
10-23. In this case, the cap structure consists of a
series of precast concrete boxes called caissons,
each of which is floated over its final location and
sunk into place by filling with rock. A single-piece
concrete cap is then cast in place on the top of each
caisson. Breakwaters and jetties are sometimes built
entirely of caissons. A typical caisson breakwater/
jetty is shown in figure 10-24. A jetty may also be
constructed to serve as a wharfage structure. If so,
it is still called a jetty.
Alongshore structures include seawalls, groins, and
bulkheads. Their main purpose is to stabilize a shoreline.
Seawalls vary widely in details of design and
materials, depending on the severity of the exposure,
the value of the property to be protected, and other
considerations. Basically, though, they consist of
some form of barrier designed to break up or reflect
the waves and a deep, tight cutoff wall to preclude
washing out of the sand or soil behind and under the
barrier. The cutoff wall is generally constructed of
timber, steel, or concrete sheet piling. Figure 10-25
Figure 10-25.-Riprap seawall.
shows a rubble-mound seawall. The stone protecting
the shoreline against erosion is called riprap. Therefore, a rubble-stone seawall is called a riprap seawall.
Various types of cast-in-place concrete seawalls
are the vertical-face, inclined-face, curved-face,
stepped-face, and combination curved-face and
stepped-face. The sea or harbor bottom along the toe
(bottom of the outside face) of a seawall is usually
protected against erosion (caused by the backpull of
receding waves) by riprap piles against the toe.
Groins, built like breakwaters or jetties, extend
outward from the shore. Again, they differ mainly in
function. A groin is used where a shoreline is in danger
of erosion caused by a current or wave action running
obliquely against or parallel to the shoreline. It is
placed to arrest the current or wave action or to deflect
it away from the shoreline.
Groins generally consist of tight sheet piling of
creosoted timber, steel, or concrete, braced with wales
and with round piles of considerable length. Groins
are usually built with their tops a few feet above the
sloping beach surface that is to be maintained or
A bulkhead has the same general purpose as a
seawall: to establish and maintain a stable shoreline.
But, whereas a seawall is self-contained, relatively
thick, and supported by its own weight, a bulkhead is
a relatively thin wall supported by a series of tie wires
or tie rods, running back to a buried anchorage
(deadman). A timber bulkhead for a bridge abutment
is shown in figure 10-26. It is made of wood sheathing
(square-edged, single-layer planks), laid horizontally.
Most bulkheads, however, are made of steel sheet
piles, an example of which is shown in figure 10-27.
The outer ends of the tie rods are anchored to a steel
wale running horizontally along the outer face of the
This wale is usually made up of pairs of steel
channels bolted together, back to back. A channel is a
structural steel member with a U-shaped section.
Sometimes the wale is placed on the inner face of the
bulkhead, and the piles are bolted to it.
The anchorage shown in figure 10-27 is covered
by backfill. In stable soil above the groundwater level,
the anchorage may consist simply of a buried timber,
a concrete deadman, or a row of driven and buried
sheet piles. A more substantial anchorage for each tie
rod is used below the groundwater level. Two
common types of anchorages are shown in figure
10-28. In view A, the anchorage for each tie rod
consists of a timber cap, supported by a batter pile. In
view B, the anchorage consists of a reinforced
concrete cap, supported by a pair of batter piles. As
indicated in the figure, tie rods are supported by piles
located midway between the anchorage and the
Bulkheads are constructed from working
drawings like those shown in figure 10-29. The detail
plan for the bulkhead shows that the anchorage
consists of a row of sheet piles to which the inner ends
Figure 10-27.-Constructed steel sheet pile bulkhead.
Figure 10-26.-Timber bulkhead for bridge abutment.
Figure 10-28.-Two types of tie-rod anchorages for bulkheads.
of the tie rods are anchored by means of a channel
In the figure, the construction sequence begins
Figure 10-29.-Working drawings for a steel sheet pile
when the shore and bottom are first excavated to the
level of the long, sloping dotted line. The sheet piles
for the bulkhead and the anchorage are then driven.
The supporting piles for the tie rods are driven next,
after which the tie rods between the bulk and the
anchorage are set in place and the wales are bolted on.
The tie rods are prestressed lightly and uniformly, and
the backfilling then begins.
The first backfilling operation consists of placing
fill over the anchorage, out to the dotted line shown in
the plan. The turnbuckles on the tie rods are then set
to bring the bulkhead plumb, and the rest of the
Moles and Jetties
A mole is simply a breakwater that serves as a
wharfage structure. The only difference is that its inner
or harbor face must be vertical and its top must
function as a deck. In a similar way, jetties also serve
as wharfage structures.
When construction is carried on below the
groundwater level, or when underwater structures like
seawalls, bridge piers, and the like, are erected, it is
usually necessary to temporarily keep the water out of
the construction area. This is typically done with well
points, cofferdams, or caissons.
backfill is worked out to the bulkhead. After the
backfilling is completed, the bottom outside the
bulkhead is dredged to the desired depth.
Well Points
As mentioned earlier, wharfage structures allow
vessels to lie alongside for loading or unloading.
Moles and jetties are the most typical forms.
Well points are long pipes thrust into the ground
down to the level at which the water must be excluded.
They are connected to each other by a pipeline system
that heads up at a water pump. Well point engineers
determine the groundwater level and the direction of
flow of the groundwater, and the well point system is
placed so as to cut off the flow into the construction
area. Well pointing requires highly specialized
personnel and expensive equipment.
The cofferdam is a temporary structure, usually
built in place, and tight enough so that the water can
be pumped out of the structure and kept out while
construction on the foundations is in progress.
Common cofferdam types are earthen, steel sheeting,
wooden sheathing, and crib. Figure 10-30 shows a
cofferdam under construction.
An earthen cofferdam is built by dumping earth
fill into the water, shaped to surround the construction
area without encroaching upon it. Because swiftly
moving currents can carry the material away, earthen
cofferdams are limited to sluggish waterways where
the velocities do not exceed 5 feet per second. Use is
also limited to shallow waters; the quantities of
material required in deep waters would be excessive
due to the flat slopes to which the earth settles when
deposited in the water. For this reason, the earthen
type is commonly combined with another type, such
as sheathing or cribbing, to reduce the quantities of
Steel is commonly used for cofferdam construction. Sheet piling is manufactured in many interlocking
designs and in many weights and shapes for varying
load conditions. The piling is driven as sheeting in a
row to forma relatively tight structure surrounding the
construction area. This pile wall is supported in
several ways. It may be supported by a framework of
stringers and struts. A cofferdam wall can consist of a
double row of piles tied together with heavy steel ties
and filled with earth. This can square, rectangular,
circular, or oval shape for stability around the
construction area.
Wooden sheathing, instead of steel, is similarly
used in cofferdam constructions. Interlocking timber
sheathing is driven as a single wall and supported by
stringers and cross struts between walls, or it is driven
in double rows as a wall. The sheathing in each row is
connected and tied with braces.
Wooden or concrete cribbing may be used in
cofferdam construction. The cribbing offers stability
Figure 10-30.-Cofferdam under construction.
to the cofferdam wall. It also provides watertightness
when filled with earth and rock.
Movable cofferdams of timber, steel, or concrete
have been built, but their uses and designs are very
similar to those discussed under boxes and open
caissons, below.
Caissons are boxes or chambers used for
construction work underwater. There are three forms
of caissons used in constructing foundations
underwater: box, open, and pneumatic caisson. If the
structure is open at the top and closed at the bottom,
it is called a box caisson. If it is open both at the top
and the bottom, it is an open caisson. If it is open at
the bottom and closed at the top, and compressed air
is used, it is a pneumatic caisson.
It is sometimes difficult to distinguish between a
cofferdam and caisson. In general, if the structure is
self-contained and does not depend upon the
surrounding material for support, it is a caisson.
However, if the structure requires such support as
sheathing or sheet piling, it is a cofferdam. Retaining
walls and piers may be built of boxes of wood, steel,
or reinforced concrete, floated into place and then
filled with various materials. These are known as
floating caissons. Open caissons may be constructed
of wood or steel sheet piling.
The preceding information provides only a basic
understanding of heavy construction. As with other
phases of construction, specialized tools and
equipment will be required. The Table of Allowance
(TOA) at your command will have these items. Follow
all safety rules and manufacturers’ recommendations
for operations and maintenance.
Although the following reference
was current when this TRAMAN was
published, its continued currency
cannot be assured. You therefore need
to ensure that you are studying the
latest revision.
Pile Construction, Field Manual 5-134, Headquarters,
Department of the Army, Washington, D.C., 1985.
ABUTMENT—Masonry, timber, or timber and earth
structures supporting the end of a bridge or an arch.
BRIDGING-Crossed or solid supports installed
between joists (floor or ceiling) to help evenly
distribute the load and brace the joists against side
BULKHEAD—A retaining wall, generally vertical.
ACOUSTICAL TILE—Any tile composed of
materials that absorb sound waves.
ALLIGATORING—A defect in a painted surface,
resulting from the application of a hard finish coat
over a soft primer. The checked pattern is caused by
the slipping of the new coat over the old coat. The
old coat can be seen through the cracks.
CAISSON—A watertight box structure surrounding
work below water.
CANTILEVER—A projecting beam supported only at
one end.
ANCHOR BOLTS—Bolts used to fasten columns,
girders, soleplates, or other members to concrete or
CASING—The trim around doors and windows.
CHASE—A vertical recess in a wall for pipes.
ANCHORS—Devices giving stability to one part of a
structure by securing it to another part, such as
toggle bolts holding structural wood members to a
masonry block wall.
COFFERDAM—A watertight enclosure.
COMPOSITE PILES—Piles formed of one material
in the lower section and another in the upper.
CONCRETE PILES—Piles made of concrete, either
cast in place or precast.
AS-BUILT DRAWINGS—Drawings made during or
after construction, illustrating how various
elements of the project were actually installed.
CORNICE—The area under the eaves where the roof
and sidewalls meet.
ASPHALT SHINGLE—A type of composition
shingle made of felt and saturated with asphalt or
tar pitch.
CREOSOTE—A coal tar distillate used for preserving
ASTRAGAL—A closure between the two leaves of a
double-swing or double-slide door to close the
joint. This can also be a piece of molding.
CRIPPLE—Any frame member shorter than a regular
CROWN—The outside curve of a twisted, bowed, or
cupped board.
BEARING PILE—A pile carrying a superimposed
vertical load.
DOLPHIN—A group of piles in water driven close
(clustered) together and tied so that the group is
capable of withstanding large lateral forces from
vessels and other floating objects.
BERM—An artificial ridge of earth.
BINDER—Hot melted pitch (or asphalt) applied
between the layers of a built-up roof to bind the
layers of felt together.
DRESSING—Trimming or planing; usually applied to
BIRD’S-MOUTH—A notch cut in the lower edge of
a rafter, to fit over the top wall plate. Formed by a
level line and a plumb cut.
DRY ROT—Fungus growth making wood soft or
BREAKWATER—A barrier constructed to shield the
interior waters of a harbor from wave forces.
DRYWALL—A system of interior wall finish using
sheets of gypsum board and taped joints.
EAVE—The part of a roof projecting over the sidewall.
JETTING—A method of forcing water around and
under a pile to displace and lubricate the
surrounding soil.
EFFLORESCENCE—A white powdery substance
forming on masonry surfaces. It is caused by
calcium carbide in the mortar.
JETTY—A term designating various types of small
wharf structures, such as a small boat jetty or a
refueling jetty. In harbor—protection works, a rock
mound or other structure extending into a body of
water to direct and confine the stream or tidal flow
to a selected channel.
END-BEARING PILE—A bearing pile deriving
practically all its support from firm underlying
ESSEX BOARD MEASURE—A method for rapidly
calculating board feet.
JOIST—Heavy pieces of lumber laid on edge
horizontally to form the floor and ceiling support
FASCIA—The flat outside horizontal member of a
cornice placed in a vertical position.
FERROUS—Any metal containing a high percentage
of iron.
LINTEL—A support beam placed over an opening in
a wall.
FOOTING—An enlargement at the lower end of a wall
to distribute the load.
FURRING—Any extra material added to another
piece or member to bring an uneven surface to a true
plane and to provide additional nailing surface.
MILLWORK—In woodworking, any material that has
been machined, finished, and partly assembled at
the mill.
MITER—A butt joint of two members at equal angles.
GAIN—An area removed by chiseling where hinges
and locks can be mounted flush with a surface.
GIRDER—A supporting beam laid crosswise to the
building; a long tress.
MOLE—A massive stone or masonry breakwater
constructed of concrete or steel sheet pile and
constructed on the inner side of a jetty for unloading
and loading ships.
GIRT—A horizontal brace; used on outside walls
covered with vertical siding.
MULLION—The division between multiple windows
or screens.
GLAZE—The process of installing glass panes in
window frames and doorframes and applying putty
to hold the glass in position.
MUNTIN—The small members dividing glass panes
in a window frame; vertical separators between
panels in a panel door.
GROIN—A bulkhead, generally made of piling, built
out from the shoreline perpendicular to the
direction of the current or drift to cut off and prevent
the carrying of beach materials along the shore.
GUSSET—A plate connecting members of a truss
PEB—Preengineered building.
PIGMENT—An insoluble coloring substance, usually
in powder form, mixed with oil or water to color
PARAPET—7he part of a wall above the roof line.
HYDRATION—The chemical reaction between
cement and water causing the cement paste to
harden and to bind the aggregates together to form
mortar or concrete.
PILE—Load—bearing member made of timber, steel,
concrete, or a combination of these materials;
usually forced into the ground.
PILE BENT—Two or more piles driven in a row
transverse to the long dimension of the structure
and fastened together by capping and (sometimes)
PILE BUTT—The larger end of a tapered pile; usually
the upper end as driven.
RISE—In a roof, the vertical distance between the plate
and the ridge. In a stair, the total height of the stair.
SASH—The movable part of a window.
SILLS—The first members of a frame set in place.
PILE CAPS—A structural member placed on top of a
pile to distribute loads from the structure to the pile.
PURLIN—Horizontal members of a roof supporting
common railers. Also, members between trusses
supporting sheathing.
QUAY—A margin wharf adjacent to the shore and
generally of solid filled construction.
SOFFIT—The underside of a subordinate member of
a building.
SPAN—The shortest distance between a pair of rafter
SPECIFICATIONS—Written instructions containing
information about the materials, style,
workmanship, and finish for the job.
STUD—The vertical members of wooden forms or
RAFTER—A sloping roof member supporting the roof
covering and extending from the ridge or the hip of
the roof to the eaves.
TRUSS—A combination of members, such as beams,
bars, and ties; usually arranged in triangular units
to forma rigid framework for supporting loads over
a span.
RAKE—The inclined position of a cornice; also the
angle of slope of a roof rafter.
RIDGE—The long joining members placed at the
angle where two slopes of a roof meet at the peak.
WAINSCOT—A wall covering for the lower part of an
interior wall; can be wood, glass, or tile.
Although the following references were current when this
TRAMAN was published, their continued currency cannot be
assured. You therefore need to ensure that you are studying the
latest revisions.
Chapter 1
Carpentry, Leonard Koel, American Technical Publishers, Inc., Alsip, Ill., 1985.
Design of Wood Frame Structures for Permanence, National Products Association,
Washington, D.C., 1988.
Exterior and interior Trim, John E. Ball, Delmar Publishers, Inc., Albany, N.Y.,
Chapter 2
Basic Roof Framing, Benjamin Barnow, Tab Books, Inc., Blue Ridge Summit, Pa.,
Chapter 3
Basic Roof Framing, Benjamin Barnow, Tab Books, Inc., Blue Ridge Summit, Pa.,
Design of Wood Frame Structures for Permanence, National Forest Products
Association, Washington, D.C., 1988.
Exterior and Interior Trim, John E. Ball, Delmar Publishers, Inc., Albany, N.Y.,
Manual of Built-up Roof Systems, Charles William Griffin, McGraw-Hill Book Co.,
New York, N.Y., 1982.
Modern Carpentry, Willis H. Wagner, Goodheart-Wilcox Co., South Holland, Ill.,
Chapter 4
Basic Roof Framing, Benjamin Barnow, Tab Books, Inc., Blue Ridge Summit, Pa.,
Design of Wood Frame Structures for Permanence, National Forest Products
Association, Washington, D.C., 1988.
Exterior and Interior Trim, John E. Ball, Delmar Publishers, Inc., Albany, N.Y.,
Modern Carpentry, Willis H. Wagner, Goodheart-Wilcox Co., South Holland, Ill.,
Chapter 5
Drywall: Installation and Application, W. Robert Harris, American Technical
Publishers, Inc., Homewood, Ill., 1979.
Modern Carpentry, Willis H. Wagner, Goodheart-Wilcox Co., South Holland, Ill.,
Wood Frame House Construction, L.O. Anderson, Forest Products Laboratory, U.S.
Forest Service, U.S. Department of Agriculture, Washington, D.C., 1975.
Chapter 6
Carpentry, Leonard Keel, American Technical Publishers, Inc., Alsip, Ill., 1985.
Exterior and Interior Trim, John E. Ball, Delmar Publishers, Inc., Albany, N.Y.,
Wood Frame House Construction, L.O. Anderson, Forest Products Laboratory, U.S.
Forest Service, U.S. Department of Agriculture, Washington, D. C., 1975.
Chapter 7
Handbook of Ceramic Tile Installation, Tile Council of America, Inc., Princeton,
N.J., 1990.
Plastering Skills, F. Van Den Branden and Thomas L. Hartsell, American Technical
Publishers, Inc., Alsip, Ill., 1984.
Chapter 8
Paints and Protective Coatings, NAVFAC-MO-110, Departments of the Army,
Navy, and Air Force, Washington, D.C., 1981.
Wood Preservation, NAVFAC-MO-312, Naval Facilities Engineering Command,
Department of the Navy, Washington, D,C., 1968.
Chapter 9
Facilities Planning Guide, NAVFAC P-437 (Revised), Naval Facilities Engineering
Command, Department of the Navy, Alexandria Va., 1989.
Chapter 10
Pile Construction, Field Manual 5-134, Headquarters, Department of the Army,
Washington, D.C., 1985.
Concrete bearing piles, 10-6
Advance base field structures, 9-1
distribution and inventory, 9-5
field-type latrines, 9-13
pre-engineered building (PEB), 9-1
Construction in the dry, 10-16
Cornices, 3-8
Door swings, 6-18
basic structural erection, 9-3
Doorframing, interior, 6-15
dissembly procedures, 9-10
Double-hung windows, 4-17
foundations, 9-2
Downspouts and gutters, 4-10
pre-erection work 9-2
Drywall, 5-1
preplanning work 9-1
SEA hut, 9-12
wood frame tents, 9-10
Enamel paint, 8-3
Aggregates, 7-2
Epoxy paint, 8-3
Air compressors, 8-10
Expansion joints, 1-33
Aluminum paint, 8-3
Anchor bolts, 9-2
Applying plaster, 7-12
Asphalt shingles, 3-18
Asphalt-felt underpayment, 3-13
Attic scuttle, 1-40
Beads, comer and casing, metal framing, 5-5
Bituminous roofing materials, 3-21
Exterior doors, 4-12
Fiber glass shingles, 3-18
Fire stops, wall framing, 1-21
Flashing, 3-15
Flexible insulation, 5-20
Floor coverings, 6-1
Floor joists, 1-8
Framing square, 2-4
Board lathe, 7-4
Bracing, wall framing, 1-17
Gable roof, 2-1
Breakwaters and jetties, 10-12
Glass and glazing, types of, 4-21
Bulkheads, 10-14
Glass-fiber felt, 3-15
Groins, 10-14
Gypsum lath, 7-6
Cantilevered joists, 1-8
Gypsum plaster, 7-1
Casement windows, 4-18
Ceiling and wall coverings, 5-1
Commercial/industrial hardware, 6-22
Header joists, 1-8
Heavy construction, 10-1
Plaster grounds, 7-8
Hip roof, 2-1
Plastering, stuccoing, and ceramic tile, 7-1
Plywood, 3-2
Pre-engineered building, 9-1
Jack rafter, 2-30
Joint reinforcing, 1-8
Resilient floor tile, 6-5
Roof coverings, 3-1
K-span building, 9-17
Roof framing, 2-1
Lacquers, 8-4
Seawalls, 10-13
Lathing accessories, 7-7
Sheet piles, 10-6
Light frame construction, 1-1
Lumber roof sheathing, 3-1
Shellac, 8-4
Stairs, 6-11
Steel bearing piles, 10-6
Metal framing, 1-30
Subfloor, 1-16
Metal lath, 7-5
Suspended acoustic ceiling systems, 5-15
Mixing plaster, 7-9
Tarred felts, 3-15
Non-wood siding, 4-3
Timber trestles, 10-1
Oil-based paints, 8-3
Varnishes, 8-3
Organic felts, 3-14
Outside wall coverings, 4-1
Wall and ceiling coverings, 5-1
Wall framing, 1-1
Paints and preservatives, 8-1
Waterfront structures, 10-11
Pile, pile driving terminology, and techniques, 10-4
Wood preservatives, 8-14
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