Rafter Span Roof Joist Span Table

Use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size.

Rafter span roof joist span table.

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. The calculated spans assume fully supported members properly sheathed and nailed on the top edge of the joist or rafter. Straight line interpolation shall be permitted for intermediate spans and design values.

Tables listing maximum spans for southern pine joists and rafters are detailed below. Surveyors span tables for designing roof rafters. 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. For pitched roofs flat roofs and ceiling joists.

These span tables assume installation of at least three joists or rafters that are spaced not more than 24 on center. Straight line interpolation shall be permitted for intermediate spans and design values. These span tables assume installation of at least three joists or rafters that are spaced not more than 24 on center.