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.
Flat roof joist sizes c16.
3 0 3 6 4 2 4 8 5 4 6 0.
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Maximum clear span of flat roof joists in metres for sc3 timber spacing between joists 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 4 38 3 99.
Spacing in exterior exposure.
Span calculator for wood joists and rafters available for the iphone.
Surveyors span tables for designing roof rafters.
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.
Fsc standard kiln dried regularised c16 treated carcassing 220 x 45mm.
It s often chosen as the standard timber for roof extensions or joist refurbishment as it s the most cost effective internal structural timber.
Fsc standard kiln dried regularised c16 treated carcassing 195 x 45mm.
This span table is to the format and methodology given in bs 5268 7 2.
For pitched roofs flat roofs and ceiling joists.
4 22 inc vat per metre.
Timber is supplied in metric sizes.
Click on a span to generate a full calculation you can adjust the exact span.
These spans were calculated using our flat roof joist calculation.
C16 timber is commonly used in floor and roof joists for internal building work.
Live load psf dead load psf span calculator for wood joists and rafters.
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.
Section mm length availability metres imperial metric.
Tables assume a minimum c16.
Sawn c16 and easy edge timber.
