These span tables apply only to flat roof and roof with a slope of up to 10 degrees.
Flat roof timber span tables c24.
Flat roof joists rafters purlin span tables ceiling joists imposed load 0 25 kn m c24 timber permissible clear spans for ceiling joists to bs 5268 7 3 imposed load 0 25 kn m.
Surveyors span tables for designing roof rafters.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
Flat roof joists rafters purlin.
For pitched roofs flat roofs and ceiling joists.
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.
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Span tables span tables can be used to determine the size of a timber member of a particular.
Maximum clear span of rafters in metres for roof pitches of between 15.
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.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
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.
Pitched roof timber sizes.
All the figures are based on roofing tiles or slates laid on timber laths over sarking felt.
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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.
This means that some values are slightly more conservative than span tables from other sources if those do not include the amended guidance.
The following tables give details of the allowable spans and spacing for some of the more common timber sizes used in traditional roofing construction.
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.
Timber to be covered these span.
