Rafter Span Roof Joist Span Table

These span tables assume installation of at least three joists or rafters that are spaced not more than 24 on center.

Rafter span roof joist span table.

Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall. For each application a pdf download is available. For pitched roofs flat roofs and ceiling joists. The calculated spans assume fully supported members properly sheathed and nailed on the top edge of the joist or rafter.

For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2. The calculated spans assume fully supported members properly sheathed and nailed on the top edge of the joist or rafter. Tables listing maximum spans for southern pine joists and rafters are detailed below. Use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size.

These span tables assume installation of at least three joists or rafters that are spaced not more than 24 on center. These 46 tables are based upon design values for visually graded southern pine dimension lumber that became effective june 1 2013. Surveyors span tables for designing roof rafters.