View size selection tables.
Timber pitched roof span tables.
View allowable load tables.
You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.
Simplified span tables for southern pine lumber and glued laminated timber glulam headers beams and girders.
For pitched roofs flat roofs and ceiling joists.
Span calculator for wood joists and rafters also available for the android os.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
View joist rafter tables.
Surveyors span tables for designing roof rafters.
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.
Also available for the android os.
Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters.
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.
For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.
All the figures are based on roofing tiles or slates laid on timber laths over sarking felt.
Pitched roof timber sizes.
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 following tables give details of the allowable spans and spacing for some of the more common timber sizes used in traditional roofing construction.
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.
These span tables apply only to flat roof and roof with a slope of up to 10 degrees.
The figures are based on quality materials.
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.
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.
Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.
