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.

Roof rafter span sizes.

Publications calculators software building codes fire safety span tables decks weights and measurement codes standards calculators software. This calculator is to be used as an estimating tool only. Weather you re building a shed roof or adding a dormer to your second story it is important to choose the proper size rafter. 2 are indicated below.

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. 1 ft 0 3048 m. Click the button to calculate the stock size needed for this job. This sizing guide for roof rafters will help determine what you need for your small project.

Roof rise this should be calculated from the base of the roof to the highest point of the roof gable the peak. Live load is weight of furniture wind snow and more. 1 in 25 4 mm. Here the number is 941 86 inches.

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. Input the rafter span on the flat eave overhang and pitch of the roof. Input the rafter span on the flat eave overhang and pitch of the roof. Dead load weight of structure and fixed loads 15 lbs ft 2.

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. 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 is the distance between rafter centres. 1 psf lb f ft 2 47 88 n m 2. Live load 20 lbs ft 2 956 n m 2. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.

Rafter and joist span faq the lengths and sizes of joists vary depending on the species and quality of the lumber used. This calculator is to be used as an estimating tool only.