Flat Roof Joist Sizes Trada

The section sizes are based on regularised als or cls timber.

Flat roof joist sizes trada.

Centre to centre spacing of joists in mm joist size width depth mm 400 450 600 400 450 600 400 450 600. Dead load per square metre in kn m supported by joists. Joists are placed on edge spaced at 400 600mm centres supported by external and internal load bearing walls. Our floor joist span tables are based on loadings given in the newer amended version of bs 6399 1.

Contains section sizes and spans for solid timber members in floors ceilings and roofs excluding trussed rafter roofs for dwellings. Surveyors span tables for designing roof rafters. 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. 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 400mm centers supporting permanent load excluding self weight of joists up to 50kg m2.

This means that some values are slightly more conservative than span tables from other sources if those do not include the amended guidance. Not more than 0 5 more than 0 5 but not more than 0 75 more than 0 75 but not more than 1. The construction of the flat roof is similar to that of the timber upper floor. The partitions should be fixed through the floor decking into the joist s beneath.

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. Part 1 introduction contents list of tables and preface. Trada and approved document part a give guidance on sizes of joists for flat roofs relating to spans and loading. Span tables for solid timber joists.

Permissible clear span metres. Tables 1 and 2 in this chapter are derived from the trada technology ltd. For timber floors between homes.