Maximum Space Between Floor Joists

With some structures floor joists are required to be 12 or 24 inches apart on center.

Maximum space between floor 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. These elements will greatly affect how far you can span your joists. For a more rigid feel 12 or less may be preferred. 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.

For example a 2 x 12 joist placed 16 oc. Spanning 16 6 between supports may cantilever up to an additional 4 1 for a total maximum length of 20 7 southern pine deck beam maximum spans. Given that 2x8s are actually 1 inches wide it works out to be 14 inches between each joist. Some builders reduce joist spacing to 12 on center to strengthen the deck frame or to increase maximum allowable joist spans.

2 grade of douglas fir are indicated below. Joist spacing for composite decking. Most decking is not strong enough to support longer spans than 16. 1 psf lb f ft 2 47 88 n m 2.

Dead load weight of structure and fixed loads 10 lbs ft 2. For example 2x6 materials can usually span 24 without any noticeable deflection and still support a significant load. 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.

Deck joist spacing should never exceed 16 on center with the exception of max deck boards which allow for maximum 24 on center. 1 ft 0 3048 m. Maximum span of 2x10 floor joist 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. I asked my local building official how he checks a deck plan to make sure the joist size and spacing combination will meet requirements of the building code he goes to the 40 lb.

This a rough guideline. Live load is weight of furniture wind snow and more. For a more rigid feel 12 or less may be preferred. Refer to the decking span table to determine what is the maximum distance that your chosen decking can span between joists.

Joists may cantilever up to of the actual adjacent span. Most decks use 16 on center spacing for joists. The rule of thumb is 6 foot span with a 2 6 on 16 centers.