Clean a Wood Deck

Wood decks accumulate dirt, mildew, and algae in layers you don't notice until spring light hits just right and you see the gray-green film coating the boards. That buildup isn't just cosmetic—it traps moisture against the wood, accelerating rot and making smooth planks treacherously slick when wet. A proper cleaning strips away organic growth and grime while preparing the surface for sealant or stain if that's your next step. The work itself is straightforward but demands attention to technique. Clean when temperatures sit between 50-80°F, cloud cover keeps the deck from drying too fast, and you have two hours of uninterrupted time. The wood should be dry before you start but won't stay that way long. Work methodically in manageable sections, never letting cleaner sit long enough to dry on the surface. Done right, you'll bring back wood grain definition you forgot was there.

1. Clear Everything Away. Remove all furniture, planters, and grills from the deck. Sweep thoroughly with a stiff broom, working debris from between boards with a putty knife or narrow scraper. Pay special attention to corners and along the house where organic matter collects.
2. Soak the Surface First. Using a garden hose with spray nozzle, thoroughly wet the entire deck surface. This prevents the wood from absorbing too much cleaner and helps it rinse more evenly. Wet the railings and stairs as well.
3. Spray Cleaner Systematically. Mix deck cleaner according to package directions in a pump sprayer or garden sprayer. Start at the far end of the deck, working backward toward your exit. Apply cleaner liberally to a 10-foot section, ensuring even coverage across all boards.
4. Scrub With the Grain. After 3-5 minutes of dwell time, scrub the section with a stiff-bristled deck brush, following the wood grain. Work the bristles into grooves and cracks where mildew hides. Maintain even pressure to avoid streaking.
5. Rinse Away All Residue. Rinse the scrubbed section completely with the garden hose, using a sweeping motion to push water off the deck edge. Ensure no cleaner residue remains. Only after rinsing should you move to the next 10-foot section.
6. Detail the Railings. Apply cleaner to railings, balusters, and stairs using a sponge or spray bottle for better control. Scrub with a smaller brush or old toothbrush for detailed areas. Rinse from top to bottom to avoid streaking.
7. Hunt Stubborn Stains. Once the deck dries enough to walk on safely, check for any remaining dark spots or stains. Apply a second treatment to problem areas only, scrub, and rinse. Some deep stains in older wood may never fully lift.
8. Wait for Complete Dryness. Keep foot traffic off the deck for 24-48 hours depending on humidity and temperature. Wood should feel completely dry to the touch and show its natural color before you apply any sealant or return furniture.