Flat Roof Joist Span

Use this table to determine the maximum lengths of floor joists based on species of lumber joist spacing and joist size.

Flat roof joist span.

Permissible clear spans for flat roof joists to bs 5268 7 2 imposed load. Span is clear span between supports. 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. Variations in ceiling construction nonparallel ceiling joist designs require additional support construction in the ceiling.

Click on a span to generate a full calculation you can adjust the exact span. Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12. 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. Maximum slop3 10 deg.

This is the distance between joist centres. Live load is weight of furniture wind snow and more. 1 in 25 4 mm. 1 ft 0 3048 m.

Also available for the android os. 1 psf lbf ft2 47 88 n m2. 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. Should refer to trada document span tables for solid timber members in floors ceilings and roofs excluding trussed rafter roofs for dwellings or ask your lbc surveyor for advice.

Find the column for your dead load and spacing and the row for your timber size to find the permissible clear span in metres. View joist rafter tables. 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. Live load 20 lbs ft2 956 n m2 maximum span ft in nominal size.

At least 40mm bearing on supports. Joist breadth 47mm. Floor joists flat roof joists assumptions at 400mm centers supporting permanent load excluding self weight of joists up to 50kg m2. Dead load weight of structure and fixed loads 15 lbs ft2.

For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.