Roof Framing Span Tables

Span tables use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.

Roof framing span tables.

The figures are based on quality materials. You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths. The tables below give maximum spans for rafters and beams. In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.

Rafter spans for southern yellow pine douglas fir and eastern spruce. Tables such as those for rafters floor joists and ceiling joists require the spacing of members to be known or selected in order to obtain the required size for a given span. Tables listing maximum spans for southern pine joists and rafters are detailed below. Span calculator for wood joists and rafters also available for the android os.

For each application a pdf download is available. These 46 tables are based upon design values for visually graded southern pine dimension lumber that became effective june 1 2013. 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. Also available for the android os.

Spacing should be interpreted as the centre to centre distance between adjacent parallel members. The spans in this table are based on a maximum supported rafter span of 16 feet where the supported span is the total horizontal distance spanned by the roof rafters divided in half not the diagonal distance or the length of the rafter. Joist and rafter span 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.

Joists rafters simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements.