Flat Roof Joist Span

Roof rafter span use this table to determine the maximum lengths of roof rafters based on species and grade of lumber spacing dimensions load and slope.

Flat roof joist span.

Live load 20 lbs ft2 956 n m2 maximum span ft in nominal size. 1 in 25 4 mm. Find the column for your dead load and spacing and the row for your timber size to find the permissible clear span in metres. Span is clear span between supports.

Floor joists flat roof joists assumptions at 400mm centers supporting permanent load excluding self weight of joists up to 50kg m2. Click on a span to generate a full calculation you can adjust the exact span. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. View joist rafter tables.

Joist spacing of 24 inches is allowed for spans between 16 to 20 feet using 2 inch by 10 inch lumber of these three grades. This is the distance between joist centres. Dead load weight of structure and fixed loads 15 lbs ft2. Also available for the android os.

Permissible clear spans for flat roof joists to bs 5268 7 2 imposed load. Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters. Variations in ceiling construction nonparallel ceiling joist designs require additional support construction in the ceiling. 1 psf lbf ft2 47 88 n m2.

Live load is weight of furniture wind snow and more. Supporting imposed load for access and repair only. Joist breadth 47mm. Usually 400 450 or 600mm but any value can be used up to 610mm max 1 2 timber strength class and joist size automatically calculate sizes suitable for supporting the loads below.

Use this table to determine the maximum lengths of floor joists based on species of lumber joist spacing and joist size. 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. Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12.

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