How to Space Decking for Proper Ventilation

Spacing Your Deck Boards During Installation is Critical

If you install decking with gaps that are too narrow, or don’t leave any gap spacing at all, you will block the air flow from under your deck . Restricted airflow will lead to the deck boards cupping. Narrow gap spacing also increases the chances leaves, and other debris can accumulate and constrict water run off. When it rains, water will pool on your deck which can lead to structural issues like checking, cupping, and mold.

To prevent structural problems, follow these general installation guidelines:

Start by creating a slope of soil under the deck that starts away from the home. Ensure the deck substructure is pitched at an angle to allow for adequate water runoff. We recommend a pitch of a 1/4" per 10 ft. for proper drainage.

When spanning the joists and laying out the decking, you must ensure even gap spacing. Gap spacing between boards can range from 1/4″ (6.35mm) to 3.32″ (2.38mm) depending on the fastening method you choose. We also suggest a minimum of 6" of open air under joists along with open sides for cross ventilation. Proper ventilation allows air from the surrounding area to flow under the joists and up through the gaps between the deck boards.

Also, you must consult with your local building department for up to date building codes. At AdvantageLumber.com we do everything in our power to give you the best chance of having a successful and safe DIY hardwood deck installation.

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