Roof Rafter Span Sizes

1 ft 0 3048 m.

Roof rafter span 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. 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. This sizing guide for roof rafters will help determine what you need for your small project.

There are several variables to consider when determining the proper rafter size. 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. 2 are indicated below.

Dead load weight of structure and fixed loads 15 lbs ft 2. Here the number is 1166 66 inches. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. 1 in 25 4 mm.

For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. 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. 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.

Rafter stock size calculator. Here the number is 941 86 inches. 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.

Live load is weight of furniture wind snow and more. This calculator is to be used as an estimating tool only. Maximum rafter spans for a patio roof in areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. This is the distance between rafter centres.

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. Rafter and joist span faq the lengths and sizes of joists vary depending on the species and quality of the lumber used.