What to spray on a deck before pressure washing?

What to spray on a deck before pressure washing?

Pre-treating a deck before pressure washing significantly improves results and reduces how much pressure you actually need to use. For wood decks, a dedicated deck cleaner or a mix of oxygen bleach and water applied with a pump sprayer helps break down mildew, algae, and gray weathering before rinsing. For composite decking, warm soapy water is typically sufficient as a pre-treatment, since composite doesn’t usually develop the same deep-set staining wood does. Let any cleaning solution dwell for the time specified on the product label, generally 10–15 minutes, without letting it dry completely on the surface. Avoid bleach-based cleaners on composite decking specifically unless the manufacturer confirms it’s safe, since some formulations can affect the surface’s color or protective coating over time.