Flat Roof Timber Sizes And Spans

Timber to be covered these span tables do not apply to timber which is fully exposed to the elements.

Flat roof timber sizes and spans.

Subject ceilings and flat roofs timber sizes and construction details 09 issued 01 04 13 rev page 1 of 2 the following tables give details of the allowable spans and spacing for some of the more common timber sizes used in ceiling and flat roof construction. In any other situation you should refer to trada document span tables for solid timber members in floors. All figures are based on normal loading conditions found in domestic construction. Span tables allow users to choose an appropriate size and stress grade to achieve spanning needs.

Surveyors span tables for designing roof rafters. All the figures are based on the normal loading conditions. Span calculator for wood joists and rafters also available for the android os. Flat the most economical flat truss for a roof is provided when the depth of the truss in inches is approximately equal to 7 of the span in inches.

Maximum rafter spans for a patio roof in areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. Also available for the android os. Roof truss span chart. The following tables give details of the allowable spans and spacing for some of the more common timber sizes used in flat roof construction.

For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. Flat roof with no permanent access and altitude not exceeding 100m 0 75 kn m udl 0 9 kn point load most areas exceeding 100m but not exceeding 200m excluding parts of scotland pennines north east england refer to bs 6399 3 1 kn m udl 0 9 kn point load. 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.

Spans in feet to out of bearing spans in feet to out of bearing 5 12 38 47 57 39 51 59 42 56 63 45 54 68. For simple construction such as domestic construction this can be determined from span table supplements in as1684 2 and as1684 3. Ceiling joist span use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size. These span tables apply only to flat roof and roof with a slope of up to 10 degrees.