Sweep the deck thoroughly with a stiff-bristled broom. Sweep away all debris and loose material, removing everything from the deck.
Spray the deck and rails with a water hose. Wet the entire structure, including the underside of the deck.
Mix mild liquid soap and water in a 5-gallon plastic bucket. Pour the soapy water onto the deck.
Scrub your deck from top to bottom with a scrub brush. Keep the deck wet with soapy water while you scrub. Let the deck dry completely before continuing.
Smooth the deck with a belt sander. Sand the deck from top to bottom including the rails and underside.
Sweep away the dust from your sanding operation. Wash away any residue with a water hose. Let the deck dry completely.
Apply a smooth, thick coat of UV-stable, epoxy sealer with a natural bristle, 3-inch brush. Let the sealer dry completely before using the deck.