Click here for structural design calculations.
Timber roof rafter span tables.
Joist and rafter span tables.
Construction details should be in accordance with as1684 2.
Span tables allow users to choose an appropriate size and stress grade to achieve spanning needs.
1 1 based on the horizontal projection of the roof rafter span.
Span tables use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.
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.
The above spans are based on american softwood lumber standard sizes.
For additional species of lumber check out the rafter span calculator from the american wood council website.
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.
Pergola rafter spans for 600 mm and 900 mm spacing.
Tables 2l and 2h list the sizes and spans for pergola or carport beams in low wind speed and higher wind speed areas.
A maximum roof pitch of 25 degrees is assumed.
Simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12.
Use these two tables for roof rafters with a slope of 3 in 12 or less.
Use these two tables for roof rafters with a slope greater than 3 in 12.
1 refer to general notes for information that is relevant for all span tables.
For simple construction such as domestic construction this can be determined from span table supplements in as1684 2 and as1684 3.
Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters.
View joist rafter tables.
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.
Wind classification n1 n2.
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.
2 for design parameters refer to figure 7 26.
3 where rafters are equal to or exceed four times their breath blocking should be used to reduce distortion.
