Proper wood deck board spacing should have at least a 1/8 inch gap after the decking has dried out. If you install your wood or treated deck boards while they are still wet boards, then they should be attached without a gap between them.

What happens if you don't space deck boards?

Without the right deck spacing, the boards may expand, cup, and buckle out of place. As a result, you may have to replace broken decking, or reinstall the boards with wider spacing to prevent further cupping and buckling, which can be time consuming and expensive.

Why is there a space between deck boards?

The most important reason to have a spacing gap is to allow the boards the room to expand and contract naturally. Wood, by nature, expands and contracts when there are seasonal humidity changes and the wood begins to absorb or expel moisture.