Select the correct side of your wood planking to face up. Look at the cut ends and find the side where the wood grain humps. This is the “bark” side and should be nailed face up to prevent “cupping.” This will allow water to drain easily off the boards.
Leave a quarter-inch between boards to allow for additional drainage.
Make sure the bottom of the deck joists are at least 6 inches above ground to avoid water intrusion from grass or ground cover below. You can also prevent water from the grass touching the bottom of the joists by covering it with landscape fabric and gravel.
Products such as Rain Escape deck drainage systems composed of a series of high-performance downspouts and troughs may also help minimize moisture intrusion too.