Floor Joist Spacing For Deck Boards

Table 1 2 or table 1 3 3.

Floor joist spacing for deck boards.

Deck joists have a different maximum span length depending upon the size spacing and framing material that you re creating your deck with. Determine the decking board thickness and direction to determine joist spacing. Decking made of 2x4s or 2x6s can span up to 24 inches. 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. 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. Why the proper deck board spacing is important. Why is joist spacing so important.

Deck board spacing provides airflow through your decking allowing evaporating air to escape. 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. 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. Again it s important to know your local codes.

For best results refer to our wood and composite deck joist span table. A house is only as strong as its foundation and a deck is only as strong as its frame. The larger the deck the larger the joists. Live load floor joist span tables in chapter 7 of the state residential code based on the 2012 international residential code.

If you use 5 4 decking joists must be no farther apart than 16 inches. 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. Recommended beam joist spans for deck framing. Then using the lumber size of joists and the joist spacing determine if you are within the maximum allowable joist span.

The last board won t look good if it s skinny or cut at an angle. Deck joist spacing should never exceed 16 on center with the exception of max deck boards which allow for maximum 24 on center. For a more rigid feel 12 or less may be preferred. Adjust the spacing between deck boards gradually over the next 10 rows of decking until the distance to the house is equal.

Decide whether the joists will cantilever over or not. If the floor joists that span the length of your deck are installed too far apart the boards on top will sag. This helps to keep your deck s framework dry and rot free.