Rafter Span Flat Roof Joist Span Tables

For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.

Rafter span flat roof joist span tables.

Limited to span in inches divided by 360. Span calculator for wood joists and rafters also available for the android os. Also available for the android os. The tables below give maximum spans for rafters and beams.

For pitched roofs flat roofs and ceiling joists. 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. Timber to be covered these span tables do not apply to timber which is fully exposed to the elements. Span tables for jois ts and rafters american wood council 4 span tables for joists and rafters american wood council design criteria.

Maximum clear span of flat roof joists in metres for sc3 timber spacing between joists size of roof joist 400mm 450mm 600mm 47 x 97 1 84 1 81 1 74. 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. 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. Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall.

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. Surveyors span tables for designing roof rafters. Strength live load of 30 psf plus dead load of 10 psf determines the required bending design value.

Deflection for 30 psf live load. 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. In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.