Roof Rafter Sizes

This is the distance between rafter centres.

Roof rafter sizes.

Rafter run outer wall this should be measured starting from the center of the roof span and then extending to the very edge of the exterior wall. Rafter slope min 15 max 45 degrees. Here the number is 941 86 inches. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.

This calculator is to be used as an estimating tool only. Input the rafter span on the flat eave overhang and pitch of the roof. For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2. This calculator is to be used as an estimating tool only.

Click the button to calculate the stock size needed for this job. Usually 400 450 or 600mm but any value can be used up to 610mm max. Rafter stock size calculator. Clear span on plan.

Input the rafter span on the flat eave overhang and pitch of the roof. The full version allows any size. It is always better to have a large rafter rather than be concerned with a sagging roof.