Timber Roof Beam Span Tables

Surveyors span tables for designing roof rafters.

Timber roof beam span tables.

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. The tables below give maximum spans for rafters and beams. Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads. View allowable load tables.

Also available for the android os. Keep in mind that these are maximums in other words shortening spans slightly will result in a more solid structure. Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters. For pitched roofs flat roofs and ceiling joists.

You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths. Tables providing size selections for various beam spans and loading combinations for southern pine dimension lumber and southern pine glued laminated timber are available for the following applications. For lesser grades spans should be shorter. These span tables apply only to flat roof and roof with a slope of up to 10 degrees.

Window door garage door headers supporting roof wall floor loads. 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. Window door garage door headers supporting roof loads only. Span calculator for wood joists and rafters also available for the android os.

The figures are based on quality materials. View size selection tables. 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.