Timber Roof Rafter Span Tables

1 1 based on the horizontal projection of the roof rafter span.

Timber roof rafter span tables.

Click here for structural design calculations. Other more complex load condition spans can be determined with our free hyne timber design 7 5 software. Wind classification n1 n2. Use these two tables for roof rafters with a slope of 3 in 12 or less.

2 for design parameters refer to figure 7 26. Roof rafter span use this table to determine the maximum lengths of roof rafters based on species and grade of lumber spacing dimensions load and slope. 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. Surveyors span tables for designing roof rafters.

Span tables allow users to choose an appropriate size and stress grade to achieve spanning needs. The above spans are based on american softwood lumber standard sizes. You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths. Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12.

Construction details should be in accordance with as1684 2. 3 where rafters are equal to or exceed four times their breath blocking should be used to reduce distortion. A maximum roof pitch of 25 degrees is assumed. Tables 2l and 2h list the sizes and spans for pergola or carport beams in low wind speed and higher wind speed areas.

Span tables for rafters to bs 5268 7 5 imposed loads of 0 75 kn m snow load are applicable to most areas where the altitude does not exceed 100 metres refer to bs 6399 3 imposed loads of 1 kn m snow load are applicable to most areas where the altitude exceeds 100 metres but does not exceed 200 metres but excluding parts of scotland. Span tables use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads. For additional species of lumber check out the rafter span calculator from the american wood council website. For simple construction such as domestic construction this can be determined from span table supplements in as1684 2 and as1684 3.

1 refer to general notes for information that is relevant for all span tables. Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters. Joist and rafter span tables. Use these two tables for roof rafters with a slope greater than 3 in 12.

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.