Flat Roof Rafter Span

Span calculator for wood joists and rafters also available for the android os.

Flat roof rafter span.

For light load roofs 24 o c. Most roof framing is 24 on center and you can still build sheds up to 14 with 2 4 rafters at 24 on center. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. 1 in 25 4 mm.

Also available for the android os. 1 psf lb f ft 2 47 88 n m 2. The imposed uniformly distributed live load in the main span. 1 ft 0 3048 m.

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. Dead load weight of structure and fixed loads 15 lbs ft 2. The tables below give maximum spans for rafters and beams.

The 1 grade. 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. Wood beam calculator american wood council website rafter and joist span faq. Loads are calculated in accordance with table 3 1 of as nzs 1170 1 2002.

Live load overhang kpa. Spacing your 2 4 shed rafters at 24 on center limits the width of your roof. For heavy loads 2x4s can span up to 5. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.

2 4 rafters can span up to 7. Input the rafter span on the flat eave overhang and pitch of the roof. 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. Click the button to calculate the stock size needed for this job.

This calculator is to be used as an estimating tool only. Click the button to calculate the stock size needed for this job. They are nailed securely to exterior wall plates and to each other. Rafter span tables use these two tables for roof rafters with a slope of 3 in 12 or less.

The rafters in a flat roof serve as ceiling joists for the space below. Live load 20 lbs ft 2 956 n m 2. Live load is weight of furniture wind snow and more. Rafter stock size calculator.

Input the rafter span on the flat eave overhang and pitch of the roof. Use these two tables for roof rafters with a slope greater than 3 in 12. The lengths and sizes of joists vary depending on the species and quality of the lumber used.