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. 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). The span values (displayed above) are from the American Softwood Lumber standard sizes. Dense elect Structural Select Structural NonDense Structural No.1 Dense No.1 NonDense No. Table 1 Floor Joists 30 psf live load, 10 psf dead load, 360 deflection. Rafters with ceiling not attached to rafters, ground snow load = 50 Psf, dead load = 20 Psf, deflection limit L/180 of Visually Graded Southern Pine Dimension Lumber Maximum spans in feet-inches. The following span table uses a moderate snow load of 50 Psf, but yours could be more or less. Selected lumber design values and span tables for these species groups are provided in this publication. Consult your local building code authority to determine the snow load in your area. Fir-Larch, Hem-Fir and Southern Pine grown in the U.S. 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 Table 1: Visually Graded Dimension Lumber 2 to 4 thick, 2 and wider Table 2: Mechanically Graded Lumber 4 thick or less, 2 and wider Table 3. 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. Table 1 provides the design values for visually graded Southern Pine dimension lumber that became effective June 1, 2013. Note also that you can break up the span of a rafter by adding a purlin and bracing to the underside. Simplified maximum span tables for selected image and mechanical grades of Southern Pine lumber in model 2×4 thru 2×12. When calculating the maximum span of a rafter, use the horizontal distance between two vertical supports. Pine yellow lumber allows recommended knots values spaced moderately uses required construction general any well quality where most high Southern yellow pine Span tables wood rafters chart joist rafter council joists table roof floor american awc irc pine southern read calculator framing.
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