Floor Joist Spacing For Deck Boards

A house is only as strong as its foundation and a deck is only as strong as its frame.

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. 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. Adjust the spacing between deck boards gradually over the next 10 rows of decking until the distance to the house is equal. For a more rigid feel 12 or less may be preferred.

If you use 5 4 decking joists must be no farther apart than 16 inches. Decking made of 2x4s or 2x6s can span up to 24 inches. 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. Recommended beam joist spans for deck framing.

Determine the decking board thickness and direction to determine joist spacing. Then using the lumber size of joists and the joist spacing determine if you are within the maximum allowable joist span. Decide whether the joists will cantilever over or not. If adding additional framing be sure to keep all boards level and in plane across the tops.

The last board won t look good if it s skinny or cut at an angle. Deck board spacing provides airflow through your decking allowing evaporating air to escape. Here s a helpful chart covering the most popular wood framing species and their maximum allowed spans. Again it s important to know your local codes.

The larger the deck the larger the joists. Why is joist spacing so important. If the floor joists that span the length of your deck are installed too far apart the boards on top will sag. For best results refer to our wood and composite deck joist span table.

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. 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. Table 1 2 or table 1 3 3.

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 helps to keep your deck s framework dry and rot free. Why the proper deck board spacing is important.