Timber Roof Joists Sizes

Section 91 2308 8 2 joists 91 2308 10 4 2 rafters b notches at the ends of joists or rafters shall not exceed one fourth the depth.

Timber roof joists sizes.

Lp solidstart i joists are more versatile than open web floor trusses and more uniform and dimensionally stable than lumber. Centre to centre spacing of joists in mm joist size width depth mm 400 450 600 400 450 600 400 450 600. 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. Usually 400 450 or 600mm but any value can be used up to 610mm max usually 400 450 or 600mm but any value can be used up to 610mm max 1 2 timber strength class and joist size.

They can be trimmed on site and long lengths allow ceilings and floors to be designed with fewer pieces saving installation time. Size of roof joist 400mm 450mm 600mm 47 x 97 1 84 1 81 1 74 47 x 120 2 43 2 39 2 27 47 x 145 3 08 3 02 2 87 47 x 170 3 75 3 67 3 42 47 x 195 4 41 4 31 3 92 47 x 220 5 04 4 85 4 41 75 x 170 4 50. Lp solidstart i joist benefits. For pitched roofs flat roofs and ceiling joists.

Span tables for flat roof joists to bs 5268 7 2 imposed loads of 0 75 kn m for maintenance and snow load are applicable where there is no permanent access no fixed ladder or staircase and most areas where the altitude does not exceed 100 metres refer to bs 6399 3. The range of joist sizes used in homes varies though between 2 by 4 inches and 2 by 12 inches. Standard size of joists though there is no standard joist size for the ceilings in all buildings most average homes use ceiling joists in a board size of 2 by 6 inches. The lengths and sizes of joists vary depending on the species and quality of the lumber used.

Surveyors and structural engineers utilise data from tables below to help calculate the correct size strength and centres of roof timbers for the required spans and loadings. Permissible clear span metres. This is the distance between joist centres. These tables can help calculate whether floor joists are strong enough to support themselves and the load they carry without the help of any walls underneath.

Surveyors span tables for designing roof rafters. Dead load per square metre in kn m supported by joists.