Flat Roof Joist Sizes Uk

As you may imagine there is a fair amount of weight involved here in terms of boards felt etc.

Flat roof joist sizes uk.

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. For pitched roofs flat roofs and ceiling joists. Solid timber joist sizes are provided in the bs 8103 3 span tables. Surveyors span tables for designing roof rafters.

Dead load per square metre in kn m supported by joists. The joists will normally be placed at 400mm centres but no more than 600mm centres. Sizes of joists needed for flat roof construction. Permissible clear span metres.

Common joists sizes are 200 x 50mm 175 x 50mm and 150 x 50mm. Timber floor joists shall be adequate for the spans and loads and be correctly installed. Centre to centre spacing of joists in mm joist size width depth mm 400 450 600 400 450 600 400 450 600. 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.

Old asbestos roofs are often replaced with flat roofs. Where the tables do not apply or where there are concentrated loads floor joists should be designed by an engineer in accordance with technical requirement r5. Not more than 0 5 more than 0 5 but not more than 0 75 more than 0 75 but not more than 1.