Roof Joist Sizes

Permissible clear span metres.

Roof joist sizes.

Centre to centre spacing of joists in mm joist size width depth mm 400 450 600 400 450 600 400 450 600. These joists easily handle spans that wood systems cannot handle while their lightweight construction makes them much less costly than steel beams. Although 2 x 4 s are included in the official table they are not listed because it is never advised to use them. Dead load per square metre in kn m supported by joists.

About o donnell metal deck. 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. It covers 2 common lumber species and sizes at 20 pounds per square foot load.

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. 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. Not more than 0 5 more than 0 5 but not more than 0 75 more than 0 75 but not more than 1. These welded steel products are used to support a building s roof and floors.