Designing Barrier

Designing Barrier
Photo courtesy Ceramiques Hugo Sanchez
Feature
Designing
Barrier-free Showers
By Dale Kempster, CSC, CTC, TTMAC
O
ver the last decade, it seems the demand and desire for barrierfree bathrooms has grown dramatically. Aside from the
importance of accessibility and universal design for those
with physical challenges, this phenomenon can be partially
attributed to ‘baby boomers’ who are now finding they are not as
mobile as in the past; some are having difficulty stepping into a tub
or even over a 150-mm (3-in.) high shower curb. Additionally, the
popularity of large hot tubs in bathrooms seems to have run its
course. Many builders have started to switch from using spaceconsuming and somewhat energy-inefficient luxury fixtures and
are instead installing multiple shower heads and sometimes a steam
generator into shower spaces.
Another factor, the ‘aging-in-place’ phenomenon, has seniors not
selling their homes and moving into retirement villages or assistedliving quarters; instead, they are modifying their homes to make them
more user-friendly as they age.
Controlling moisture
One of the top challenges when designing and building barrier-free
showers is moisture management. This is a systematic method to
contain water in both liquid and vapour form and enable it to pass
through an assembly predictably and efficiently using materials
not adversely affected by moisture.
Virtually no material can completely eliminate water vapour
transmission. In recognition of this fact, the terminology for a
vapour ‘barrier’ was changed a few years ago to vapour ‘retarder’—
the only true vapour barrier would be solid glass or metal. The
standard for thin, load-bearing waterproof membranes that can
have tile directly bonded to them is American National Standards
Institute (ANSI) A118.10, Load-bearing, Bonded, Waterproof
Membranes for Thin-set Ceramic Tile and Dimension Stone
Installations. This standard, however, is only for waterproofing and
does not have any performance criteria for vapour transmission
which is commonly tested under ASTM E96, Standard Test
Methods for Water Vapor Transmission of Materials.
Given the mentioned prospect of multiple shower heads and
steam-generators, it is very important the substrates (i.e. walls,
floors, and showers) are waterproof and, in most cases, resistant to
steam/vapour. The Tile, Terrazzo, and Marble Association of Canada
(TTMAC) has recently revised its Detail 321 SR, “Tile Installed
in Steam Rooms,” in the 2011–12 Specification Guide 09 30 00
Tile Installation Manual, calling out that the waterproofing
membrane should have a perm rating of 0.5 or less (previously <
1.0) using ASTM E96 at 90 per cent humidity. This is in recognition
of the high service requirements found in steam-shower and
steam-room applications.
Construction height
Another challenge in barrier-free applications is limiting
construction height. This is a particular challenge when using a
shower pan method with a two-stage drain and a mortar-bed
(Figure 1). This method will create excessive construction height
as the minimum thickness of the mortar bed will be 31 mm (1.2
in.) at the lowest point which will then increase by approximately 6
mm (0.24 in.) in every 305 mm (12 in.) to create the slope required
for drainage. Depending on the size of the shower the construction
height can easily increase to 54 mm (2.1 in.) or thicker, which in
barrier-free construction will cause impediments at the entrance
to the bathroom.
Figure 1
TILE
BOND COAT
WATERPROOF MEMBRANE IF REQUIRED
BACKER / BOARD
VAPOUR RETARDER
WOOD OR METAL STUDS
OR SOLID BACKING
SEALANT
OPTIONAL REINFORCED MOTAR BED
SLOPING SCREED
SHOWER PAN LINE OR
WATERPROOF MEMBRANE
CONCRETE SLAB OR WOOD FLOOR
SLOPE TO DRAIN
GROUP JOINT
A shower pan assembly using a two-stage drain.
Options with drains
The early 1990s’ arrival of ANSI A118.10 membranes was followed
about a decade later by the introduction of drains with an integrated
bonding flange. This way, a thin, load-bearing waterproof membrane
could be adhered to the drain, making a waterproof connection at the
top of the assembly. The advantage of this method is the low
construction height can be maintained as these types of drains can be
directly installed onto the substrate, with no mortar bed required.
Slope can be started from almost zero and, again, depending on the size
of the shower room, heights can be maintained relatively low. For instance,
a shower with a 1220-mm (48-in.) radius will have a construction height
of only 24 mm (1 in.). These membranes are typically continued up the
wall onto solid backing to ensure the assemblies are waterproof. In other
cases, a high-density expanded polystyrene (EPS) board with bondable/
waterproof facers can be substituted if nothing has been attached to the
studs. The advantages of these boards are their light weight, R-value,
vapour resistance, and the fact they can be cut with a utility knife onsite.
Another new entry into barrier-free bathrooms that expands the
design opportunities is the introduction of linear drains. Several
manufacturers have launched products that allow drains to be placed
in different strategic locations. Most of them work with an ANSI
A118.10 membrane and, like the integrated bonding flange drains, the
linear drains allow for low construction height assemblies as they can
be installed directly onto the substrate. Additionally, employing a linear
drain enables the design of floors that have only one or two slopes,
which allows for large-format tile or even stone slabs to be installed in
the shower area.
Standard drains that are 100 to 150 (4 to 6 in.) x 100 to 150 mm
only allow use of small-format tile because the floor either has to be
designed in a cone configuration or made into four planes to direct
water to the drain. In most cases, tiles no larger than 305 x 305 mm
(12 x 12 in.) can be used to evacuate water. Linear drains, on the other
hand, can be placed:
Images courtesy Schluter-Systems
In 1971, Statistics Canada cited eight per cent of the country’s
population as being 65 years and older. Last year, this number had
increased to almost 15 per cent—nearly five million people.
The number of people older than 65 is forecast to grow by an
additional 900,000 in the next five years, suggesting the need for
barrier-free housing will continue to increase.
Over the last couple of years, advancement in building material
technology allows for barrier free bathrooms that are relatively
easy to construct, functional, and perform extremely well.
The main objective of this article is to identify the various
challenges of constructing a barrier-free bathroom and offer
several solutions and recommendations to make the design and
building of these spaces relatively painless.
SEMI-DRY AREA
WET AREA
WALL TILE
SEMI-DRY AREA
THIN SET MORTAR
WATERPROOFING MEMBRANE
WATERPROOFING MEMBRANE
THIN SET MORTAR
SOLID BACKING
TILE BASE
WATERPROOFING MEMBRANE
THIN SET MORTAR
SOLID BACKING
TILE BASE
WATERPROOFING MEMBRANE
DRAIN WITH INTEGRATED
BONDING FLANGE
SHOWER TRAY OR MORTAR BED
DRAIN WITH INTEGRATED
BONDING FLANGE
FLOOR TILE
FLOOR TILE
SLOPED TO DRAIN
RECESSED SUBFLOOR
This assembly shows a recessed subfloor in the shower area, using
a mortar bed or prefabricated tray over a concrete slab, with a
special drain and a bonding flange that tie into the surface-applied
waterproofing membrane.
SEMI-DRY AREA
WET AREA
SLOPED TO DRAIN
SUBFLOOR
In this situation, the bathroom floor has been raised outside the
shower area, with the pre-slope to the drain falling away from
the raised bathroom floor. It uses a drain with a bonding flange,
surface-applied waterproofing, and small tiles on the shower floor.
WALL TILE
THIN SET MORTAR
SEMI-DRY AREA
WET AREA
WALL TILE
THIN SET MORTAR
WATERPROOFING MEMBRANE
WATERPROOFING MEMBRANE
THIN SET MORTAR
THIN SET MORTAR
SOLID BACKING
TILE BASE
WATERPROOFING MEMBRANE
WALL TILE
WET AREA
THIN SET MORTAR
TILE BASE
SOLID BACKING
WATERPROOFING MEMBRANE
SHOWER TRAY OR MORTAR BED
UNCOUPLING MEMBRANE
DRAIN WITH INTEGRATED
BONDING FLANGE
FLOOR TILE
RECESSED SUBFLOOR
*BLOCKING OR CROSS SUPPORTS REQUIRED
CONSULT ENGINEER OR CONTRUCTION PROFESSIONAL
This assembly shows construction over a wood subfloor. The subfloor
in the shower area is recessed, which means there is no change in
floor height outside of the shower area.
SEMI-DRY AREA
WET AREA
WALL TILE
THIN SET MORTAR
WATERPROOFING MEMBRANE
TILE BASE
WATERPROOFING MEMBRANE
FLOOR TILE
THIN SET MORTAR
SOLID BACKING
SHOWER TRAY OR MORTAR BED
DRAIN WITH INTEGRATED
BONDING FLANGE
SUBFLOOR
The floor area has been built up over a concrete slab. The floor
inside the shower area slopes to a centre drain, and the floor
outside the shower area slopes away to the bathroom door.
LINEAR DRAIN
FLOOR TILE
SLOPED TO DRAIN
SUBFLOOR
The bathroom floor area has been raised, and it falls away from the
shower threshold to a linear drain that has been located on the
furthest wall. The single slope allows large tiles on the shower floor.
• adjacent to the wall where the showerhead is located, which would
allow for a single slope;
• in the middle of the shower floor that would have two slopes
converging to the drain; or
• in the threshold in front of the shower area, which also would allow
for a single-slope floor.
Avoiding slips and falls
The number-one culprit of injury in both residential and commercial
applications is slip-and-fall incidents. Until recently, the main
test method used by the tile industry to determine slip resistance
was ASTM C028, Standard Test Method for Determining the Static
Co-efficient of Friction of Ceramic Tile and Other Like Surfaces by the
Horizontal Dynamometer Pull-meter Method, which is also known as
the static co-efficient of friction (SCOF) test.
However, this test method was somewhat controversial as test
results were not always consistent; there were also concerns for the
testing of wet conditions regarding a condition called ‘stiction’—a
surface tension phenomenon similar to how two plates of glass with
Photos courtesy Ceramiques Hugo Sanchez
The importance of accessibility for an aging population means an increase in barrier-free showers. Fortunately, advancement in
building material technology allows these spaces to be not only easily constructed, but also eye-catching.
water in between stick together. This would give artificially
higher ratings in comparison to the actual traction of the
surface in question.
This year, with the revision of the TTMAC Tile Installation
Manual, it was decided to withdraw use of ASTM C1028 for slip
resistance and acknowledge a new test that has been ratified and
referenced in ANSI A137.1-2011, American National Standards
Specifications for Ceramic Tile. This new test method—which has
been designated as the dynamic co-efficient of friction (DCOF)
Acutest—employs the BOT 3000, a type of testing apparatus that
measures parameters in the field of tribology, such as frictional
forces, co-efficient of friction, and effects of lubrication.
In the past, using the ASTM C1028 test method, the
recommended SCOF was 0.5 wet as recognized by the revised
TTMAC Tile Installation Manual. Now, employing the new
BOT 3000 testing apparatus, the designated threshold value of
0.42 or greater has been designated for interior spaces expected
to be walked on when wet. To determine whether a specific tile
or stone will meet this criterion, TTMAC or another third
party can conduct this test at a nominal charge.
Benches and floor panels
Benches are a desirable and popular feature in barrier-free
showers as they allow the user to sit in comfort and safety while
bathing. This design feature has been aided by the availability of
prefabricated benches made of solid EPS blocks, or assembled-
in-place extruded polystyrene (XPS) or EPS foam panels. Both
versions allow for benches to be configured in many dimensions
that are 100 per cent waterproof and require neither framing nor
an elaborate fastening system.
A final new technology available for barrier-free bathrooms
is prefabricated floor panels that are made with one, two, or four
slopes. Typically, these EPS products are not only user-friendly,
but also contribute additional benefits. The reality is utilizing
a pre-sloped shower panel makes it simple to create a flat and
plumb surface to reduce the possibility of lippage and ‘bird baths’
in the floor surface of the bathroom.
For example, because they are made of a thermalresistant material with an R-value of approximately 4 per
25 mm (1 in.) of thickness, the tile has some insulation
so it is not as cold as being bonded to a mortar-bed or
concrete slab. Additionally, the weight is substantially
reduced versus a mortar bed or concrete levelling bed,
which weighs approximately 80 kg/m 2 (16 lb/sf ) at 38 mm
(1 ½ in.). Depending on the density of the XPS panel,
there are also sound attenuation contributions. For woodframe construction, the National Building Code of Canada
(NBC) requires a minimum of 48.82 kg/m 2 (10 lb/sf ) dead
load and 195.29 kg/m 2 (40 lb/sf ) live load, so the saving in
weight by using a prefabricated shower tray can eliminate
the need to add extra reinforcement such as blocking or an
additional I-joist.
These images show two shower areas fully waterproofed
and ready for tile. One can see the waterproofing
membrane and linear drain inside the shower area, along
with the uncoupling membrane outside of the shower area.
Conclusion
Although they can be complicated to construct, with some
proper planning and use of new materials such as integrated
bonding flange drains, linear drains, prefabricated trays, and EPS
wall boards, these types of bathrooms can be more durable. As
shown in the photos throughout this article, the ‘next-generation’
bathroom can be both functional and elegant—it is just a matter
of recognizing the challenges and executing the solution.
Dale Kempster, CSC, CTC, TTMAC, is the technical director of SchluterSystems (Canada), and has been with the company for 25 years. He is
currently vice-president of the Materials, Methods, and Standards
Association (MMSA) in the United States, and was on the Terrazzo, Tile,
and Marble Association of Canada’s (TTMAC’s) board of directors for
14 years. Kempster co-chairs the Specifications and Technical Research
Committee and is chair of the TTMAC 09 30 00 Tile Installation
Manual. He is the current chair of the Canadian Advisory Committee
for the International Organization for Standarization (ISO [TC189]).
Kempster also co-chairs the MMSA Sound-control Committee and
served as co-chairperson of the MMSA Crack-isolation Committee. He is
a graduate of the Certified Tile Consultants (CTC) program given by the
Ceramic Tile Institute of America (CTIOA). Kempster can be reached
via e-mail at [email protected]
Design Tips for Going Barrier-free
T
he great advantage of barrier-free showers is they are
more functional than their traditional counterparts.
They provide easy access for anyone—especially children,
the elderly, and those with reduced mobility. Further, the
absence of doorsills and corners makes them easier to
maintain. Seamless floor transitions also maximize floor space
by making the shower look and ‘feel’ bigger. This is particularly
true for small bathrooms where glass doors are eliminated to
make the space more functional and practical.
Floor thickness options
In basements and condominiums, where all the floors are concrete
slabs, there is no other way to go than ‘up’ to achieve the required
slope to the drain. Building up the floor with a mortar bed or
pre-formed, sloped trays are the preferred options.
For conventional wood construction, floor thickness can
often be reduced by removing the existing floor buildup. This
allows the mortar bed to be laid directly atop a single-layer
subfloor. In the bathroom areas outside the shower (i.e. where
there is no mortar bed), it is essential to use an uncoupling
member when installing tile over a single-layer subfloor. This
membrane provides uncoupling and waterproofing in the
bathroom area.
There are also exceptional cases, where the floor substrate
could be lowered to accommodate a seamless bathroom
floor transition. However, this requires the services of an
engineer as the original floor joists cannot be simply cut
and weakened without risking serious consequences to the
floor assembly and building structure.
Waterproofing
Extending the waterproofing out to cover the whole
bathroom floor is always a good practice as water inevitably
is carried out beyond the shower, barrier-free or traditional.
Radiant heating
The popularity of heated floors in bathrooms and shower
areas has rapidly increased over the last few years. Heated
floors come either as electrical radiant wires or hose systems
carrying heated water. The former is easier to install and
less expensive. Radiant floors can and should be used
under shower floors for comfort, but also to help evaporate
humidity from the tile assembly, which in turn reduces
bacteria buildup on showers with less maintenance.
Hugo Sanchez of Ceramiques Hugo Sanchez specializes in the
design and installation of barrier-free bathrooms. He can be
contacted via e-mail at [email protected]
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