Floor Joist Spacing For Deck Boards

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.

Floor joist spacing for deck boards.

In most cases it s best to start with a full board on the outside edge of the deck and work toward the house so the odd board is less visible. Table 1 2 or table 1 3 3. In typical deck construction with a ledger on one side of the joist and beam on the other the size of the joists is driven by the size of the deck and based on the general maximum spans mentioned above. For a more rigid feel 12 or less may be preferred.

Why is joist spacing so important. Why the proper deck board spacing is important. If you will run decking at an angle you might need to put the joists closer together. Here s a helpful chart covering the most popular wood framing species and their maximum allowed spans.

Deck joists have a different maximum span length depending upon the size spacing and framing material that you re creating your deck with. The bigger you make your deck the more you ask of the framing timbers that hold up the deck s structure and the joists and beams that support the. This helps to keep your deck s framework dry and rot free. If adding additional framing be sure to keep all boards level and in plane across the tops.

If you use 5 4 decking joists must be no farther apart than 16 inches. Recommended beam joist spans for deck framing. If the floor joists that span the length of your deck are installed too far apart the boards on top will sag. Then using the lumber size of joists and the joist spacing determine if you are within the maximum allowable joist span.

While the gap in your deck boards may seem like a small step in a deck project the gap size you choose serves a significant purpose. Live load floor joist span tables in chapter 7 of the state residential code based on the 2012 international residential code. Again it s important to know your local codes. Decking made of 2x4s or 2x6s can span up to 24 inches.

Determine the decking board thickness and direction to determine joist spacing. Decking boards span from joist to joist. Deck joist spacing should never exceed 16 on center with the exception of max deck boards which allow for maximum 24 on center. The last board won t look good if it s skinny or cut at an angle.

The larger the deck the larger the joists. A house is only as strong as its foundation and a deck is only as strong as its frame. Decide whether the joists will cantilever over or not.