Sizing Floor Joist Spans

Live load is weight of furniture wind snow and more.

Sizing floor joist spans. The lengths and sizes of joists vary depending on the species and quality of the lumber used. Also available for the android os. Let s expand our house beyond that 17 2 span capability to 24 feet wide. The floor joist spacing is the distance between the centers of any two installed joists.

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. 1 ft 0 3048 m. 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.

Joist span and spacing is set by your local building code. 1 psf lb f ft 2 47 88 n m 2. 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. So the house dimensions will now be 24 x 13. 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. See the image below for an example of joists spaced 16 on center 16 o c.

True floor joist span calculations can only be made by a structural engineer or contractor. Since the example house we are designing for is 12 feet wide we need to find in the floor joist span table a joist size and centering that can span 12 or wider. 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. The widest span in the floor joist span table in part 2 of this tutorial module showed that floor joists can span 17 2 if they are 2 x 12s spaced 12 o c.

2 grade of douglas fir are indicated below. The 1 grade material is more expensive than the 2 grade but if you can use fewer or. Rafter and joist span faq.