What Is Floor Joist Spacing

Live load is weight of furniture wind snow and more.

What is floor joist spacing.

Two options that arise could be your wider 24 and your narrower 12 options for spacing. With some structures floor joists are required to be 12 or 24 inches apart on center. Normally floor joists are spaced 16 inches apart on center. The floor joist spacing is the distance between the centers of any two installed joists.

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. Dead load weight of structure and fixed loads 10 lbs ft 2. 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. 2 grade of douglas fir are indicated below.

2x8s are used frequently for these projects. 1 psf lb f ft 2 47 88 n m 2. 2 8 s come standard at 1 inch thick. Maximum floor joist span for no.

The larger the deck the larger the joists. You should check with your local building department for construction requirements in your area. 1 ft 0 3048 m. A 2x8 up to 12 feet.

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. In general terms joists spaced 16 inches on center can span 1 5 times in feet their depth in inches. This means from the center of one upright joist to the center of the next. Given that 2x8s are actually 1 inches wide it works out to be 14 inches between each joist.

True floor joist span calculations can only be made by a structural engineer or contractor. See the image below for an example of joists spaced 16 on center 16 o c.