Lumber Size For Roof Rafters

Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.

Lumber size for roof rafters.

Dead load weight of structure and fixed loads 15 lbs ft 2. Lumber size width 2x8 2x10 or 2x12 boards will be used to estimate cost of each rafter as well as total cost excluding local sales tax. As a general rule roofs that have a high human occupancy rate should be framed with rafters every 16 structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes. Live load 20 lbs ft 2 956 n m 2.

This is based upon the span of the rafter horizontal span not total rafter length live and dead loads. If you re building rafters and aren t sure where to start when determining the length of your lumber you re in the right place our rafter stock size calculator shows you how long your rafters should be so you ll know what you need in terms of framing lumber dimensional lumber studs and more. Click the button to calculate the stock size needed for this job. More roof calculators roof truss calculator.

Rafter and joist span faq. This calculator is to be used as an estimating tool only. 1 ft 0 3048 m. 1 psf lb f ft 2 47 88 n m 2.

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. Spf 2 6 rafters can span 8. Just enter the dimensions of the roof rise and run to get started. 2 are indicated below.

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. To size joists and rafters use the maximum span tables for southern yellow pine. 1 in 25 4 mm. Rafters longer than 20 feet.

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. Therefore if you want a 10 12 single sloped roof and you live in a heavy snow area then you can space your rafters 16 apart and use spf 2 6 lumber. This rafter span calculator is species specific for douglas fir hemlock etc.

The lengths and sizes of joists vary depending on the species and quality of the lumber used. Rafter spacing and roof length will be used to determine quantity of rafters needed for your project. Home improvement stores do not sell pine boards longer than 20 feet.