Flat Roof Timber Joist Sizes

Eurocode 5 span tables for solid timber members in floors ceilings and roofs for dwellings 3rd edition.

Flat roof timber joist sizes.

For timber floors between homes. Bs 5268 7 1 was published before bs 6399 1. 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. Span tables for solid timber joists.

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. If supporting lightweight partitions running parallel to joists provide two additional joists under each partition. For pitched roofs flat roofs and ceiling joists. Size of joists mm clear span c16 joist m clear span c24 joist m 47 x 95 47 x 120 47 x 145 47 x 170 47 x 195 47 x 220 1 77 2 40 2 89 3 38 3 87 4 36 2 04 2 75 3 47 4 20 4 93 5 66 floor joists flat roof joists assumptions at.

Greater than 2400 mm and 3 6 kn load per metre width of floor for spans less than 2400 mm to ensure that very small joist sizes do not result from the calculations for smaller spans. A cavity closer should be provided to the top of the walls to prevent fire spread and to stop damp air entering the roof space. 1 2 timber strength class and joist size automatically calculate sizes suitable for supporting the loads below c16 cost effective for most applications c24 stronger more demanding c14 c18 c22 c27 c30 c35 c40. The section sizes are based on regularised als or cls timber.

Surveyors span tables for designing roof rafters. And the row for your timber size to find the permissible clear span in metres. 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.

Tables 1 and 2 in this chapter are derived from the trada technology ltd. Where a new flat roof abuts an existing external wall the joists can be hung on metal joist hangers which are fixed to a horizontal timber plate wall bolted to the wall. Flat roof joists rafters purlin. These span tables apply only to flat roof and roof with a slope of up to 10 degrees.

Notches are not to exceed 0 125 of the depth of the joist and are to be located between 0 07 and 0 25 of the span from the support. Rafter and joist span faq.