Timber Roof Joist Span Tables

Joist and rafter span tables.

Timber roof joist span tables.

View joist rafter tables. Span tables use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads. 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. For pitched roofs flat roofs and ceiling joists.

Timber and concrete upper floors. Solid timber joist sizes are provided in the bs 8103 3 span tables. 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. 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.

You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths. Timber to be covered these span tables do not apply to timber which is fully exposed to the elements. Span tables span tables can be used to determine the size of a timber member of a particular strength class required for a given span. They also tell you what the maximum spacing should be between each section or timber member 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.

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. Also available for the android os. Technical diagram on page 35 30mm m aximum allow able sp ans mm sheet roof spacing mm rafter size 600 760 900 1000 1200 66 x 30 850 750 700 700 600 90 x 30 1200 1050. These span tables apply only to flat roof and roof with a slope of up to 10 degrees.

Timber floor joists shall be adequate for the spans and loads and be correctly installed. Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters. Construction details should be in accordance with as1684 2. Span calculator for wood joists and rafters also available for the android os.