Trace where rain and meltwater will go
Look at the house connection, doors, ground below the deck and nearby drainage paths. Surface boards do not replace flashing or solve water directed toward a building. The finished layout should not obstruct drainage or access to components that need maintenance.
Follow the selected system’s gap and clearance instructions. Those details allow for movement as well as drainage; a single generic gap is not suitable for every product.
Keep the underside in the discussion
Low decks and enclosed sides can create different conditions from an open raised deck. Check ventilation, ground clearance and any skirting against the product requirements and site design.
Under-deck drainage systems have their own installation and maintenance rules. Confirm compatibility before using the space below as a dry storage or living area.
Before the boards conceal the details
Review water protection and ventilation with the installer. Keep photos of concealed connections, access points and the drainage assembly. Identify who handles maintenance and how the system can be inspected later.
For existing decks, combine this review with the resurfacing assessment.