Roof Rafter Sizes

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.

Roof rafter sizes.

Roof rise this should be calculated from the base of the roof to the highest point of the roof gable the peak. It is always better to have a large rafter rather than be concerned with a sagging roof. Here the number is 1166 66 inches. This calculator is to be used as an estimating tool only.

Rafter stock size calculator. Usually 400 450 or 600mm but any value can be used up to 610mm max. Here the number is 941 86 inches. Clear span on plan.

The full version allows any size. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. Click the button to calculate the stock size needed for this job. Input the rafter span on the flat eave overhang and pitch of the roof.

Rafter slope min 15 max 45 degrees. 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. This is the distance between rafter centres.