Common and Jack Rafters Calculator
Span =
Rise =
Spacing = 16
Common Rafters
Common =
Difference =
Jack Rafters
1st Jack =
2nd Jack =
3rd Jack =
4th Jack =
5th Jack =
6th Jack =
7th Jack =
8th Jack =
9th Jack =
10th Jack =
11th Jack =
12th Jack =
factor =
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Calculates the common rafter of a roof framing system based on the span of the building and the slope of the roof. Also calculates the length of each jack rafter that is required for this installation.
[https://infinitysw.s3.amazonaws.com/cengage/Rafter1.png]
Rows
-Span: Span (full width) of the roof.
-Rise: Rise of the roof in units relative to run. For example, if the roof rises 4 inches for each 12 inches of horizontal run, enter 4.
-Spacing: Space from center-to-center of the rafters.
-Common: Length of the common rafter to be installed.
-Difference: Difference between the length of each jack rafter when installed to be level and flush with the base of the common rafter. (see image)
- Jack Rafters 1-14: each jack rafter length.
Examples
Calculate the common rafter length for a building that is 14' wide and will be be built with a 4:12 slope. Rafters will be installed 16" on-center.
-Span: 14ft
-Rise: 4
-Spacing: 16in o.c.
The results are:
-Common: 7ft 4&9/16in
-Difference: 1ft 4&7/8in
-1st Jack: 5ft 11&11/16in
-2nd Jack: 4ft 6&13/16in
-3rd Jack: 3ft 1&15/16in
-4th Jack: 1ft 9&1/16in
-5th Jack: 4&3/16in
[https://infinitysw.s3.amazonaws.com/cengage/rafter2.png]
Keywords
Span
Rise
Spacing
Common
Difference
1st Jack
2nd Jack
3rd Jack
4th Jack
5th Jack
6th Jack
7th Jack
8th Jack
9th Jack
10th Jack
11th Jack
12th Jack
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