Rafter Span Roof Joist Span Table

For pitched roofs flat roofs and ceiling joists.

Rafter span roof joist span table.

For each application a pdf download is available. 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. These span tables assume installation of at least three joists or rafters that are spaced not more than 24 on center.

Tables listing maximum spans for southern pine joists and rafters are detailed below. Straight line interpolation shall be permitted for intermediate spans and design values. Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall. 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.

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