Maximum Space Between Floor Joists

Joists may cantilever up to of the actual adjacent span.

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. 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. 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. 2 grade of douglas fir are indicated below.

Dead load weight of structure and fixed loads 10 lbs ft 2. Live load is weight of furniture wind snow and more. 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. Given that 2x8s are actually 1 inches wide it works out to be 14 inches between each joist.

Most decks use 16 on center spacing for joists. Maximum floor joist span for no. Deck joist spacing should never exceed 16 on center with the exception of max deck boards which allow for maximum 24 on center. Some builders reduce joist spacing to 12 on center to strengthen the deck frame or to increase maximum allowable joist spans.

For example 2x6 materials can usually span 24 without any noticeable deflection and still support a significant load. For a more rigid feel 12 or less may be preferred. Most decking is not strong enough to support longer spans than 16. For example a 2 x 12 joist placed 16 oc.

These elements will greatly affect how far you can span your joists. Live load floor joist span tables in chapter 7 of the state residential code based on the 2012 international residential code. Builders can adjust their choice of lumber size and spacing depending on circumstances. This means from the center of one upright joist to the center of the next.

Joist spacing for composite decking. For a more rigid feel 12 or less may be preferred. The rule of thumb is 6 foot span with a 2 6 on 16 centers. With some structures floor joists are required to be 12 or 24 inches apart on center.

1 psf lb f ft 2 47 88 n m 2. Refer to the decking span table to determine what is the maximum distance that your chosen decking can span between joists. This a rough guideline.