How to Clean a Deck Before Sealing

Clean your deck thoroughly by removing furniture and debris, sweeping, power washing or scrubbing with deck cleaner, then allowing 48 hours to dry completely before applying sealant.

1. Clear Every Inch First. Remove all furniture, planters, grills, and decorations from the deck surface. This gives you full access to every board and corner. Store items in your garage or cover them with tarps if leaving nearby.
2. Sweep Out Hidden Debris. Use a stiff-bristled broom to sweep off leaves, dirt, and loose debris. Pay attention to gaps between boards where debris collects. A leaf blower works well for stubborn debris in cracks.
3. Activate the Cleaner. Mix deck cleaner according to package directions in a pump sprayer or large bucket. For general cleaning, use oxygen bleach-based cleaners. For mildew or algae, use a cleaner with sodium hypochlorite. Apply evenly across all surfaces and let sit for the recommended time, usually 10-15 minutes.
4. Scrub With the Grain. Use a stiff-bristled brush or deck brush to scrub the entire surface, working with the grain of the wood. Focus extra attention on high-traffic areas, stains, and discolored spots. For large decks, work in manageable sections to prevent the cleaner from drying out.
5. Blast Away All Residue. Rinse the deck completely with a pressure washer set to 1500-2000 PSI, or use a garden hose if power washing isn't available. Work systematically from one end to the other, ensuring all cleaner residue is removed. Keep the pressure washer nozzle moving to avoid gouging the wood.
6. Patience Seals the Deal. Let the deck dry completely for at least 48 hours before sealing. Check that the wood surface is completely dry by touching it and ensuring no moisture remains in the grain. Drying time may be longer in humid conditions or if the deck doesn't receive direct sunlight.