These span tables apply only to flat roof and roof with a slope of up to 10 degrees.
Timber pitched roof span 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.
You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.
View size selection tables.
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.
Pitched roof timber sizes.
The tables below give maximum spans for rafters and beams.
Also available for the android os.
All the figures are based on roofing tiles or slates laid on timber laths over sarking felt.
The following tables give details of the allowable spans and spacing for some of the more common timber sizes used in traditional roofing construction.
Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.
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 figures are based on quality materials.
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.
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.
Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch.
View joist rafter tables.
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.
In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.
Surveyors span tables for designing roof rafters.
Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters.
Span calculator for wood joists and rafters also available for the android os.
For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.
Simplified span tables for southern pine lumber and glued laminated timber glulam headers beams and girders.
