Lumber Size For Roof Rafters

Spf 2 6 rafters can span 8.

Lumber size for roof rafters.

If you move the rafters closer together at 16 o c then your syp rafters will span 11 and spf up to 10. More roof calculators roof truss calculator. 1 ft 0 3048 m. Input the rafter span on the flat eave overhang and pitch of the roof.

The lengths and sizes of joists vary depending on the species and quality of the lumber used. 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. Trying to find what size lumber to use. To size joists and rafters use the maximum span tables for southern yellow pine.

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. Home improvement stores do not sell pine boards longer than 20 feet. Rafters longer than 20 feet. 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.

Rafter and joist span faq. 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. 2 are indicated below. 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.

This rafter span calculator is species specific for douglas fir hemlock etc. Live load 20 lbs ft 2 956 n m 2. Click the button to calculate the stock size needed for this job. This calculator is to be used as an estimating tool only.

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. 1 psf lb f ft 2 47 88 n m 2. This is based upon the span of the rafter horizontal span not total rafter length live and dead loads. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.

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