KEYSTROKE DISPLAY
1. Use trigonometry formula (divide the rise by the hypotenuse): o o
6 f ÷ 1 0 f =
0.
0.6
2. Solve for angle or degrees:minutes:seconds:
Ç ç (cos -1 ) 53.13°
Ç • (dms deg) DMS 53.07.48
Common Rafter Length
Find the point-to-point length of the
Common rafter on a 7/12-pitched roof with a span of 28 Feet. What are the angle cuts?
KEYSTROKE DISPLAY
1. Enter Pitch: o o
7 i p PTCH 7
0.
INCH
2. Enter half the span as the run:
2 8 f ÷ 2 =
R
14
RUN 14
FEET
FEET
0
0
INCH
INCH
3. Find the Common and cuts: d d d
DIAG 16
FEET
2-1/2
INCH
PLMB 30.26°
LEVL 59.74°
P
OCKET
R
EFERENCE
G
UIDE
— 25
Regular Hip/Valley and Jack Rafters
A roof’s Pitch is 9/12 and half the total span is 6 Feet. Find the lengths of the
Common, Hip/Valley and Jack rafters.
Also find the incremental jack adjustment and the cut angles. (Jack rafters at 16”
On-center spacing.)
KEYSTROKE DISPLAY
1. Find the Common rafter length: o o
6 f R
9 i p
RUN 6
FEET
0
PTCH 9
0.
INCH
INCH d (Common) DIAG 7
FEET
6
INCH
2. Find the Hip/Valley rafter length and cut angles; then the incremental jack adjustment, Jack rafter lengths and cut angles:
H
H
H
H j j j j j
H/V 9
JKOC
FEET
STORED
7-1/4
PLMB 27.94°
LEVL 62.06°
CHK1 45.00°
INCR 1
JK 1 5
FEET
FEET
JK 2 4
JK 3 2
FEET
FEET
16
8
10
2
6
INCH
INCH
INCH
INCH
INCH
INCH
P
OCKET
R
EFERENCE
G
UIDE
— 26
