Flat Roof Joist Sizes

Douglas fir maximum horizontal roof rafter span for lumber grade selected structural and no.

Flat roof joist sizes. Usually 400 450 or 600mm but any value can be used up to 610mm max 1 2 timber strength class and joist size automatically calculate sizes suitable for supporting the loads below. Old asbestos roofs are often replaced with flat roofs. As you may imagine there is a fair amount of weight involved here in terms of boards felt etc. The range of joist sizes used in homes varies though between 2 by 4 inches and 2 by 12 inches.

K series joists range in depth from 10 to 30 and can span up to 60. The lengths and sizes of joists vary depending on the species and quality of the lumber used. Sizes of joists needed for flat roof construction. Live load is weight of furniture wind snow and more.

1 psf lb f ft 2 47 88 n m 2. 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 are indicated below. This is the distance between joist centres.

Dead load weight of structure and fixed loads 15 lbs ft 2. So any timber joists that are used need to be strong enough to support this weight. About o donnell metal deck. These joists easily handle spans that wood systems cannot handle while their lightweight construction makes them much less costly than steel beams.

Rafter and joist span faq. These welded steel products are used to support a building s roof and floors. 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.