Roof Joist Sizes

2 x 12 s are not listed because you can span pretty much whatever you want.

Roof joist sizes. K series joists range in depth from 10 to 30 and can span up to 60. The difference in the joist sizes applies to the width of the boards which determines the height of the ceiling. These joists easily handle spans that wood systems cannot handle while their lightweight construction makes them much less costly than steel beams. Dead load per square metre in kn m supported by joists.

This ceiling joist span table is based on the 2012 irc for uninhabitable attics with limited storage. It covers 2 common lumber species and sizes at 20 pounds per square foot load. 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.

Centre to centre spacing of joists in mm joist size width depth mm 400 450 600 400 450 600 400 450 600. These welded steel products are used to support a building s roof and floors. Although 2 x 4 s are included in the official table they are not listed because it is never advised to use them. Permissible clear span metres.