Typical Floor Joist Spacing

Live load is weight of furniture wind snow and more.

Typical floor joist spacing.

With some structures floor joists are required to be 12 or 24 inches apart on center. Joist span and spacing is set by your local building code. 1 psf lb f ft 2 47 88 n m 2. This means from the center of one upright joist to the center of the next.

Normally floor joists are spaced 16 inches apart on center. 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. 1 ft 0 3048 m. 2 grade of douglas fir are indicated below.

Live load 30 lbs ft 2 1436 n m 2. 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. 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.

Floor joist table joist size joist spacing maximum span 2 x 6 12 on center 10 0 16 9 1 19 2 8 7 24 7 11 2 x 8 12 on center 13 2 16 12 0 19 2 11 3 24 10 2 2 x 10 12 on center 16 10 16 15 2. You should check with your local building department for construction requirements in your area. Maximum floor joist span for no. True floor joist span calculations can only be made by a structural engineer or contractor.

Given that 2x8s are actually 1 inches wide it works out to be 14 inches between each joist. See the image below for an example of joists spaced 16 on center 16 o c. Dead load weight of structure and fixed loads 10 lbs ft 2. Two options that arise could be your wider 24 and your narrower 12 options for spacing.

Below is a table giving the minimum size floor joists needed for 16 and 24 on center o c spacing when using 2 lumber with 10 pounds per square foot of dead load and 40 pounds of live load.