How to Use the Hip Roof Framing Calculator

The hip roof framing calculator returns the value of the main rafter, the side rafter, the length of the hip, the height of the knee wall, and the lengths of the jack rafters.

Select the following information by using the drop downs to enter values in feet and inches.

Span for the main rafters (measure from outside of wall to outside of wall; they must must be on the same level!)
Thickness of the ridge (Find this on the materials list or in the yard)
Roof pitch for the main rafters (Find this on the blueprints)
Roof pitch for the side rafters (Find this on the blueprints)
Width of the cornice (do not include wall sheathing unless the rafter span and the bird’s mouth include it)

Once these values are selected the calculator will automatically fire these results

Run of the common rafter (Use this measurement to determine where the side rafter sits)
Rise of the common rafter (Use this to calculate a ridge prop and scaffold height; remember to include the HAP)
Length of the common rafters (This is measured from long to short on the top of the rafter)
Difference in HAP (This is the difference in heights at the HAP of the common and side rafter)
Run of the side rafters (Use this to determine where the common rafters stop on the main walls)
Length of the side rafters (This is measured from long to short on the top of the rafter)
Off set of the hips
Length of the hips