6 4 8 timber joist spans timber floor joists shall be adequate for the spans and loads and be correctly installed.

Timber flat roof joist span tables. Determine roof load width for floor joists. For simple construction such as domestic construction this can be determined from span table supplements in as1684 2 and as1684 3. Surveyors span tables for designing roof rafters. Span tables can be used to determine the size of a timber member of a particular strength class required for a given span.

Span tables for ceiling joists to bs 5268 7 3 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. 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. These span tables apply only to flat roof and roof with a slope of up to 10 degrees. Tables with a suffix l are for low wind speed areas n1 n2 n3 and c1.

Span tables f7 rafters 30mm 11 f7 rafters 42mm 14 verandah beams f7 42mm sheet roof 17 verandah beams f7 42mm tile roof 20 verandah beams gl8 sheet roof 21 verandah beams gl8 tile roof 24 ridge beams f7 42mm sheet roof 25 ridge beams f7 42mm tile roof 28 internal floor joists f7 42mm 30. Flat roof with no permanent access and altitude not exceeding 100m 0 75 kn m udl 0 9 kn point load most areas exceeding 100m but not exceeding 200m excluding parts of scotland pennines north east england refer to bs 6399 3 1 kn m udl 0 9 kn point load. They also tell you what the maximum spacing should be between each section or timber member. For pitched roofs flat roofs and ceiling joists.

Supporting load bearing walls and lintels. Span tables allow users to choose an appropriate size and stress grade to achieve spanning needs. Timber to be covered these span tables do not apply to timber which is fully exposed to the elements. 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.

Other more complex load condition spans can be determined with our free hyne timber design 7 5 software. Click here for structural design calculations. For alternative species and larger spans refer as 1684. 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.

Solid timber joist sizes are provided in the bs 8103 3 span tables. Tables 1 2 5 and 10 list the recommended sizes and spans for the most commonly available timber species. 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.

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