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.

Roof rafter sizes.

Input the rafter span on the flat eave overhang and pitch of the roof. Click the button to calculate the stock size needed for this job. Rafter slope min 15 max 45 degrees. Rafter stock size calculator.

Here the number is 1166 66 inches. It is always better to have a large rafter rather than be concerned with a sagging roof. Roof rise this should be calculated from the base of the roof to the highest point of the roof gable the peak. Input the rafter span on the flat eave overhang and pitch of the roof.

If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. Usually 400 450 or 600mm but any value can be used up to 610mm max. Clear span on plan. This calculator is to be used as an estimating tool only.

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. Here the number is 941 86 inches. This calculator is to be used as an estimating tool only.