![]() ![]() To calculate the maximum spans of species not shown above, use the Span Calculator or the Span Tables for Joists and Rafters on the American Wood Council website. ![]() I, David J King, being a Chartered Professional Engineer and currently holding an Annual Practising Certificate, certify that the span tables have been prepared using widely accepted engineering principles. To calculate maximum rafter spans using different design criteria (load, snow load, spacing, grade, etc.) for these common lumber species, see the International Residential Code (IRC). Incorporating span tables for: Verandah beams, rafters and posts GL8 grade. The span values (displayed above) are from the American Softwood Lumber standard sizes. Rafters with ceiling not attached to rafters, ground snow load = 50 Psf, dead load = 20 Psf, deflection limit L/180 Free UK Span Table for Rafters to BS 5268-7.5 (C24, 0.75 kN/m² load, slope 22.5° or more but less than 30°) - Timber Beam Calculator. The following span table uses a moderate snow load of 50 Psf, but yours could be more or less. (ringed in red. The tables below give maximum spans for rafters and beams. EXAMPLE: A rafter span of 4,80 meters for roof sheeting without a ceiling will require a 38X228 S5 Rafter. ![]() Rafters can be omitted as they are not structural in the application. For heavy roofs or in areas with substantial snowfall or winds, call your local building department for code requirements. For over 50 years Wilson Timbers have been serving and supplying quality timber and hardware to professional and owner builders, as well as the DIY renovator. CB150-16 Beam span table used W 3600 (Width of Frame / Rafter span) 6410 (Fascia Beam span) The CB150-16 beam achieves the 6000mm span for the fascia beam and can be used for the rafters. Consult your local building code authority to determine the snow load in your area. In areas with mild climates, patio roofs are generally designed for loads of 30 psf (pounds per square foot). Note: Snow load factors can be specific to the regional location of a structure. Rafter Span Tables Rafters with ceiling not attached to rafters, live load = 20 Psf, dead load = 20 Psf, deflection limit L/180 The braces need to be supported by a bearing wall, shown in the diagram above.Įxample: In the rafter span table below, the highlighted cell (13-0) indicates that a 2" x 8" Douglas Fir rafter, with a grade of #2, spaced 24" apart, can have a maximum span of 13 feet - 0 inches (13-0) if designed for a live load of 20 Psf, and dead load of 20 Psf. Click on a span to generate a full calculation (you can adjust the exact span). Find the column for your dead load and spacing, and the row for your timber size to find the permissible clear span in metres. Note also that you can break up the span of a rafter by adding a purlin and bracing to the underside. Permissible Clear Spans for Flat Roof Joists (to BS 5268-7.2) Imposed load. When calculating the maximum span of a rafter, use the horizontal distance between two vertical supports. ![]()
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