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COMMON RAFTER LENGTH
Example: If a roof has a 7/12 Pitch and span of 14 Feet 4 Inches, what is the point-to-point length of
the point-to-point length of the Common rafter (excluding the overhang or ridge adjustment)? What are
the Plumb and Level cuts?
Note: Run is half the Span.
KEY INPUT & DISPLAY
1. Find diagonal or point-to-point length of the Common rafter:
On/C
On/C
7
Inch
Pitch
1
4
4
Feet
Run
Diag
2. Find Plumb and Level cuts:
Diag
Diag
Note: The Common rafter calculation is the "point-to-point" length and does not include the overhang or ridge
adjustment.
COMMON RAFTER LENGTH - PITCH UNKNOWN
Example: Find the common rafter length for a roof with a rise of 8 Feet 10-1/2 Inches and a run of 16
Feet 8 Inches. Solve for the Pitch in Degrees and in Inches.
KEY INPUT & DISPLAY
Find Diagonal and Pitch:
On/C
On/C
8
1
0
Feet
1
6
8
Feet
Diag
Pitch
Pitch
14' 4" Span
7' 2" Run
÷
=
2
Inch
1
/
2
Rise
Inch
Inch
Run
Page 35
0
PTCH 7
Inch
7
2
Feet
Inch
RUN 7
2
Feet
Inch
DIAG 8
3-9/16
Feet
Inch
PLMB 30.26˚
LEVL 59.74˚
0
RISE 8
10-1/2
Feet
Inch
RUN 16
8
Feet
Inch
DIAG 18
10-9/16
Feet
Inch
PTCH 6-3/8
Inch
PTCH 28.04˚
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