Flat Roof Rafter Span

Live load is weight of furniture wind snow and more.

Flat roof rafter span.

For light load roofs 24 o c. 2 4 rafters can span up to 7. Input the rafter span on the flat eave overhang and pitch of the roof. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.

The 1 grade. Live load overhang kpa. 1 ft 0 3048 m. Use these two tables for roof rafters with a slope greater than 3 in 12.

Input the rafter span on the flat eave overhang and pitch of the roof. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. The size of rafters for a flat roof depends on the horizontal span of the building the type and grade of timber used and the load on the roof. Spacing your 2 4 shed rafters at 24 on center limits the width of your roof.

Wood beam calculator american wood council website rafter and joist span faq. The imposed uniformly distributed live load in the main span. Click the button to calculate the stock size needed for this job. The tables below give maximum spans for rafters and beams.

They are nailed securely to exterior wall plates and to each other. Dead load weight of structure and fixed loads 15 lbs ft 2. This calculator is to be used as an estimating tool only. Live load 20 lbs ft 2 956 n m 2.

This calculator is to be used as an estimating tool only. For heavy loads 2x4s can span up to 5. The lengths and sizes of joists vary depending on the species and quality of the lumber used. The above spans are based on american softwood lumber standard sizes.

Rafter stock size calculator. Rafter span tables use these two tables for roof rafters with a slope of 3 in 12 or less. Click the button to calculate the stock size needed for this job. This is set by the roof use you selected in the previous screen and cannot be modified.

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. Span calculator for wood joists and rafters also available for the android os. Loads are calculated in accordance with table 3 1 of as nzs 1170 1 2002. The rafters in a flat roof serve as ceiling joists for the space below.

Most roof framing is 24 on center and you can still build sheds up to 14 with 2 4 rafters at 24 on center. 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. 2 are indicated below.