Timber Roof Span Tables

For simple construction such as domestic construction this can be determined from span table supplements in as1684 2 and as1684 3.

Timber roof span tables.

You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths. Technical diagram span tables f7 rafters 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 1250 1150 1050 1000 950 90 x 30 1650. 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. A maximum roof pitch of 25 degrees is assumed.

Construction details should be in accordance with as1684 2. Span tables use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads. Wind classification n1 n2. 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.

Other more complex load condition spans can be determined with our free hyne timber design 7 5 software. 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. 1 refer to general notes for information that is relevant for all span tables. Surveyors span tables for designing roof rafters.

For pitched roofs flat roofs and ceiling joists. 2 for design parameters refer to figure 7 26. Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run. 3 where rafters are equal to or exceed four times their breath blocking should be used to reduce distortion.

Pergola rafter spans for 600 mm and 900 mm spacing. Joist and rafter span tables.