Roof Joist Sizes

Dead load per square metre in kn m supported by joists.

Roof joist sizes.

The range of joist sizes used in homes varies though between 2 by 4 inches and 2 by 12 inches. About o donnell metal deck. A 2 by 4 inch joist for instance hangs into the room by 4 inches which may leave the ceiling high while a 2 by 12 inch joist in the same position hangs 12 inches into the room which decreases the ceiling height by 8 inches. Although 2 x 4 s are included in the official table they are not listed because it is never advised to use them.

It covers 2 common lumber species and sizes at 20 pounds per square foot load. 2 x 12 s are not listed because you can span pretty much whatever you want. Centre to centre spacing of joists in mm joist size width depth mm 400 450 600 400 450 600 400 450 600. K series joists range in depth from 10 to 30 and can span up to 60.

Not more than 0 5 more than 0 5 but not more than 0 75 more than 0 75 but not more than 1. Permissible clear span metres. 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. This ceiling joist span table is based on the 2012 irc for uninhabitable attics with limited storage.