Lumber Size For Roof Rafters

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Lumber size for roof rafters.

1 psf lb f ft 2 47 88 n m 2. 1 in 25 4 mm. Rafter spacing and roof length will be used to determine quantity of rafters needed for your project. The lengths and sizes of joists vary depending on the species and quality of the lumber used.

Trying to find what size lumber to use. This calculator is to be used as an estimating tool only. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. More roof calculators roof truss calculator.

Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. Live load is weight of furniture wind snow and more. Spf 2 6 rafters can span 8. Rafter and joist span faq.

2 are indicated below. Live load 20 lbs ft 2 956 n m 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. 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.

To size joists and rafters use the maximum span tables for southern yellow pine. This rafter span calculator is species specific for douglas fir hemlock etc. 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. Home improvement stores do not sell pine boards longer than 20 feet.

Input the rafter span on the flat eave overhang and pitch of the roof. This is based upon the span of the rafter horizontal span not total rafter length live and dead loads. 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. Just enter the dimensions of the roof rise and run to get started.

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. Rafters longer than 20 feet. 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.