Roof Joist Spacing

Ceiling joist spacing in inches 12 16 19 2 24 species and grade of lumber.

Roof joist spacing. If the roof is not completely square you can decrease the space between joists but never increase the space. In other words you would space a roof joist 15 inches apart from another roof joist but never 17 inches apart. Use these two tables for roof rafters with a slope greater than 3 in 12. Maximum rafter spans for a patio roof.

For additional species of lumber check out the rafter span calculator from the american wood council website. 1 psf lb f ft 2 47 88 n m 2. Live load is weight of furniture wind snow and more. Spacing in exterior exposure.

Joist spacing of 24 inches is allowed for spans between 16 to 20 feet using 2 inch by 10 inch lumber of these three grades. While most residential construction uses 2x8 joists with 16 inch spacing there are many other factors you need to consider when determining the proper joist span length. Joist span and spacing is set by your local building code. Dead load weight of structure and fixed loads 15 lbs ft 2.

Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. 2 are indicated below. Variations in ceiling construction nonparallel ceiling joist designs require additional support construction in the ceiling. For example the highlighted cell below shows that a 2 x 6 southern yellow pine joist with a grade of 2 and spaced 24 apart can have a maximum span of 10 feet 0 inches 10 0 if you are designing your structure to support a plaster ceiling.

Use these two tables for roof rafters with a slope of 3 in 12 or less. Live load psf dead load psf span calculator for wood joists and rafters available for the iphone. So the space between rafters can be greater without reducing the maximum span. The same concept holds true for roof trusses.

Span calculator for wood joists and rafters also available for the. Various lumber size options 2 4 2 6 2 8 2 10 the maximum ceiling joist span based on the lumber size species grade and spacing used. A roof joist is always spaced no more than 16 inches apart from another roof joist. 1 ft 0 3048 m.

You should check with your local building department for construction requirements in your area.