Floor Joist Support Span

Joist span table use these tables to determine floor joist spans based on grade of lumber size of joist floor joist spacing and a live load of 30 lbs ft 2 or 40 lbs ft 2 these tables can also be used to determine deck joist span.

Floor joist support span.

1 ft 0 3048 m. 1 psf lb f ft 2 47 88 n m 2. For example if you double the thickness or number of joists in a floor the distance the boards can span will increase by approximately 25. Maximum floor joist span for no.

When building a house or even a deck it is important to confirm you have the correct joist sizes spans and spacing before you get started. Span calculator for wood joists and rafters also available for the android os. The layout term for joists is on center which is the center to center measurement from one joist to the next. Let s expand our house beyond that 17 2 span capability to 24 feet wide.

This sample table gives minimum floor joist sizes for joists spaced at 16 inches and 24 inches on center o c for 2 grade lumber with 10 pounds per square foot of dead load and 40 pounds of live load which is typical of normal residential construction. Joist span and spacing is set by your local building code. The illustrations one for cantilever joists and one for flush rim beam hung joists point out where joist span measurements are taken from the saddle of the ledger mounted joist hanger to the center of a dropped beam or saddle of the. Span entries are listed for 2 6 through 2 12 joists and 12 in 16 in and 24 in.

Live load is weight of furniture wind snow and more. Most decks use 16 on center spacing for joists. Most decking is not strong enough to support longer spans than 16. 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.

Dead load weight of structure and fixed loads 10 lbs ft 2. Rafter spans can be extended slightly beyond what the rafter tables suggest when there is a cantelever extending beyond the supporting wall. 2 grade of douglas fir are indicated below. Also available for the android os.

So the house dimensions will now be 24 x 13. Ceiling joist span use this table to determine the maximum lengths of ceiling joists based on species of lumber joist spacing and joist size. True floor joist span calculations can only be made by a structural engineer or contractor.