Max Floor Joist Spacing

A few of the most common factors that affect joist span include.

Max floor joist spacing.

Given that 2x8s are actually 1 inches wide it works out to be 14 inches between each joist. Span entries are listed for 2 6 through 2 12 joists and 12 in 16 in and 24 in. In general terms joists spaced 16 inches on center can span 1 5 times in feet their depth in inches. Reading the table you ll see that 2 x 8s installed 16 apart on center can span 12 4.

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. However when running spf 2 6 floor joists into the floor joist calculator referenced above you get a maximum span of 9 feet 8 inches with a minimum bearing length of 3 inches at each end on 12 centers. This a rough guideline. With some structures floor joists are required to be 12 or 24 inches apart on center.

Span calculator for wood joists and rafters also available for the android os. True floor joist span calculations can only be made by a structural engineer or contractor. Also available for the android os. The larger the deck the larger the joists.

2 grade of douglas fir are indicated below. Maximum span of 2x12 floor joist the most important design choices to consider when building a home are the species and grade of wood that is being used as well as joist size and spacing. A 2x8 up to 12 feet. The rule of thumb is 6 foot span with a 2 6 on 16 centers.

1 psf lbf ft2 47 88 n m2. So our house would look like the picture below with all floor joists 2 x 8. 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. Normally floor joists are spaced 16 inches apart on center.

Live load is weight of furniture wind snow and more. Dead load weight of structure and fixed loads 10 lbs ft2. 2x10 to 15 feet and 2x12 to 18 feet. These elements will greatly affect how far you can span your joists.