This calculator is to be used as an estimating tool only.
Roof rafter sizes and spans.
Rafter stock size calculator.
1 ft 0 3048 m.
Input the rafter span on the flat eave overhang and pitch of the roof.
The loads are based on adjusted roof snow loads from the governing building code.
The lengths and sizes of joists vary depending on the species and quality of the lumber used.
Live load is weight of furniture wind snow and more.
Structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes.
2x4 2x6 2x8 2x10 2x12.
1 in 25 4 mm.
To size joists and rafters use the maximum span tables for southern yellow pine.
Use these two tables for roof rafters with a slope of 3 in 12 or less.
1 psf lb f ft 2 47 88 n m 2.
Rafter and joist span faq.
The above spans are based on american softwood lumber standard sizes.
If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center.
This calculator is to be used as an estimating tool only.
Floor joists ceiling joists rafters snow load rafters roof live load deflection limit.
More roof calculators roof truss calculator how to cut rafters.
It is always better to have a large rafter rather than be concerned with a sagging roof.
Use these two tables for roof rafters with a slope greater than 3 in 12.
Click the button to calculate the stock size needed for this job.
Dead load weight of structure and fixed loads 15 lbs ft 2.
For additional species of lumber check out the rafter span calculator from the american wood council website.
Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.
Live load 20 lbs ft 2 956 n m 2.
Area span on the flat.
For roof live loads less than 20 pounds per square foot psf rafter spans and required e values tabulated for 20 psf shall be permitted to be adjusted in accordance with the fol lowing table.
2 are indicated below.
This rafter span calculator is species specific for douglas fir hemlock etc.
3 stud construction standard utility.
This is based upon the span of the rafter horizontal span not total rafter length live and dead loads.
Spacing in 12 16 19 2 24.
Rafter spans are tabulated for the most common roof loads.
L 720 l 600 l 480 l 360 l 240 l 180.
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.
Rafter stock size calculator.
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.
