Roof Joist Sizes And Spans

For pitched roofs flat roofs and ceiling joists.

Roof joist sizes and spans.

Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters. Standard size of joists though there is no standard joist size for the ceilings in all buildings most average homes use ceiling joists in a board size of 2 by 6 inches. 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. Using table f 2 figure 3 check each lumber size to see if a 16 inch spacing will permit a span of 15 feet 1 inch.

These spans were calculated using our flat roof joist calculation engine. This span table is to the format and methodology given in bs 5268 7 2. Click on a span to generate a full calculation you can adjust the exact span. Surveyors span tables for designing roof rafters.

The range of joist sizes used in homes varies though between 2 by 4 inches and 2 by 12 inches. This ceiling joist span table is based on the 2012 irc for uninhabitable attics with limited storage. Step 2 span table. Rafter and joist span faq.

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. It covers 2 common lumber species and sizes at 20 pounds per square foot load. Click here for structural design. Spans of timber joists in suspended timber ground floors span tables.

Although 2 x 4 s are included in the official table they are not listed because it is never advised to use them. View joist rafter tables. The lengths and sizes of joists vary depending on the species and quality of the lumber used. 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.

Strength class timber c16 sc3 and c24 sc4 span tables. The table of contents indicates that table f 2 watches these loading conditions. Joist span and spacing is set by your local building code. These span tables are the equivalent of other industry standard span tables and are calculated to the same standards.

Select the appropriate table in span tables for joists and rafters. 2 x 12 s are not listed because you can span pretty much whatever you want.