Rafter Span Flat Roof Joist Span Tables

Straight line interpolation shall be permitted for intermediate spans and design values.

Rafter span flat roof joist span tables.

These span tables apply only to flat roof and roof with a slope of up to 10 degrees. Dead load weight of structure and fixed loads 15 lbs ft 2. Span calculator for wood joists and rafters also available for the android os. Use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size.

For pitched roofs flat roofs and ceiling joists. Surveyors span tables for designing roof rafters. 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.

Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall. These span tables assume installation of at least three joists or rafters that are spaced not more than 24 on center. 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. Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters.

1 ft 0 3048 m. Timber to be covered these span tables do not apply to timber which is fully exposed to the elements. 1 psf lb f ft 2 47 88 n m 2. 2 are indicated below.

Also available for the android os. In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. Notches are not to exceed 0 125 of the depth of the joist and are to be located between 0 07 and 0 25 of the span from the support.

For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. View joist rafter tables. The figures are based on quality materials.