Roof Rafter Span Sizes

Input the rafter span on the flat eave overhang and pitch of the roof.

Roof rafter span sizes.

1 psf lb f ft 2 47 88 n m 2. 1 ft 0 3048 m. Click the button to calculate the stock size needed for this job. For example you can span a 1 grade no knots southern yellow pine a greater distance than a 2 grade with knots southern yellow pine.

Roof rise this should be calculated from the base of the roof to the highest point of the roof gable the peak. This is the distance between rafter centres. Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter. Input the rafter span on the flat eave overhang and pitch of the roof.

Live load 20 lbs ft 2 956 n m 2. Publications calculators software building codes fire safety span tables decks weights and measurement codes standards calculators software. 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 sizing guide for roof rafters will help determine what you need for your small project.

Here the number is 941 86 inches. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. Dead load weight of structure and fixed loads 15 lbs ft 2. Live load is weight of furniture wind snow and more.

1 in 25 4 mm. This calculator is to be used as an estimating tool only. Here the number is 1166 66 inches. There are several variables to consider when determining the proper rafter size.

Rafter stock size calculator. Usually 400 450 or 600mm but any value can be used up to 610mm max. Click the button to calculate the stock size needed for this job. This calculator is to be used as an estimating tool only.

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. 2 are indicated below.