Roof Joist Spacing

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.

Roof joist spacing.

1 psf lb f ft 2 47 88 n m 2. An essential part of planning a patio roof or gazebo project is determining the number size and spacing of rafters beams and posts according to the loads they will carry. Use these two tables for roof rafters with a slope greater than 3 in 12. Spacing in exterior exposure.

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. Common spacing for trusses on this type of building is often between 2 and 4 feet but trusses built with advanced designs may allow spacing as great as 8 or 12 feet. Span calculator for wood joists and rafters also available for the.

Joist span and spacing is set by your local building code. 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. Maximum rafter spans for a patio roof. The above spans are based on american softwood lumber standard sizes.

Use these two tables for roof rafters with a slope of 3 in 12 or less. For additional species of lumber check out the rafter span calculator from the american wood council website. 1 ft 0 3048 m. Live load is weight of furniture wind snow and more.

The same concept holds true for roof trusses. Ceiling joist spacing in inches 12 16 19 2 24 species and grade of lumber. Dead load weight of structure and fixed loads 15 lbs ft 2. A roof joist is always spaced no more than 16 inches apart from another roof joist.

You should check with your local building department for construction requirements in your area. 2 are indicated below. Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no. Live load psf dead load psf span calculator for wood joists and rafters available for the iphone.

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.