Select the appropriate table in span tables for joists and rafters.
Roof joist sizes and spans.
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.
2 x 12 s are not listed because you can span pretty much whatever you want.
For example you can span a 1 grade no knots southern yellow pine a greater distance than a 2 grade with knots southern yellow pine.
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.
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.
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 are the equivalent of other industry standard span tables and are calculated to the same standards.
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.
Step 2 span table.
Joist span and spacing is set by your local building code.
For floor and ceiling construction surveyors can calculate the size strength and centres spacing of joists with reference to the data in these tables.
The range of joist sizes used in homes varies though between 2 by 4 inches and 2 by 12 inches.
The lengths and sizes of joists vary depending on the species and quality of the lumber used.
This ceiling joist span table is based on the 2012 irc for uninhabitable attics with limited storage.
View joist rafter tables.
This span table is to the format and methodology given in bs 5268 7 2.
Strength class timber c16 sc3 and c24 sc4 span tables.
The table of contents indicates that table f 2 watches these loading conditions.
For pitched roofs flat roofs and ceiling joists.
It covers 2 common lumber species and sizes at 20 pounds per square foot load.
Surveyors span tables for designing roof rafters.
Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters.
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.
These spans were calculated using our flat roof joist calculation engine.
Click on a span to generate a full calculation you can adjust the exact span.
