Flat Roof Rafter Span

For heavy loads 2x4s can span up to 5.

Flat roof rafter span.

2 4 rafters can span up to 7. 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. The above spans are based on american softwood lumber standard sizes. Wood beam calculator american wood council website rafter and joist span faq.

1 psf lb f ft 2 47 88 n m 2. Also available for the android os. Click the button to calculate the stock size needed for this job. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.

Input the rafter span on the flat eave overhang and pitch of the roof. This calculator is to be used as an estimating tool only. Most roof framing is 24 on center and you can still build sheds up to 14 with 2 4 rafters at 24 on center. Rafter span tables use these two tables for roof rafters with a slope of 3 in 12 or less.

2 are indicated below. Loads are calculated in accordance with table 3 1 of as nzs 1170 1 2002. They are nailed securely to exterior wall plates and to each other. The imposed uniformly distributed live load in the main span.

1 in 25 4 mm. This calculator is to be used as an estimating tool only. The rafters in a flat roof serve as ceiling joists for the space below. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.

1 ft 0 3048 m. Live load 20 lbs ft 2 956 n m 2. For light load roofs 24 o c. Use these two tables for roof rafters with a slope greater than 3 in 12.

Spacing your 2 4 shed rafters at 24 on center limits the width of your roof. This is set by the roof use you selected in the previous screen and cannot be modified. Dead load weight of structure and fixed loads 15 lbs ft 2. Live load is weight of furniture wind snow and more.

Click the button to calculate the stock size needed for this job. Live load overhang kpa. The tables below give maximum spans for rafters and beams. Input the rafter span on the flat eave overhang and pitch of the roof.

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. The 1 grade. The lengths and sizes of joists vary depending on the species and quality of the lumber used.