How to Clean a Deck: Wood and Composite Step-by-Step
Cleaning a deck properly means using different methods for wood versus composite boards. For wood decks, oxygen bleach and a stiff brush restore color and kill mildew without damaging the wood fibers. For composite decking, a gentle soap and water scrub is usually enough. This guide walks through both methods, plus stain removal and seasonal maintenance tips.
What You’ll Need
- Garden hose or pressure washer (max 1,500 PSI for wood; 1,200 PSI for composite)
- Stiff-bristle deck brush
- Oxygen bleach (OxiClean or similar — NOT chlorine bleach) for wood decks
- Dish soap or composite deck cleaner for composite boards
- Bucket and warm water
- Putty knife or stiff wire brush (for between boards)
- Rubber gloves and eye protection
- Deck brightener (optional, for wood)
- Deck sealer or stain (for seasonal protection)
Safety and Precautions
Wet deck boards are extremely slippery — never step on them with bare feet or smooth-soled shoes. Wear rubber-soled shoes with grip. Keep children and pets off the deck while cleaning. Don’t use chlorine bleach on wood decks — it degrades the wood fibers and leaves the deck gray and brittle over time. Oxygen bleach is the safe, effective alternative. Never exceed 1,500 PSI with a pressure washer on wood — it splinters the grain. Always wear eye protection when pressure washing. Note the products you should never mix with each other by reviewing our cleaning safety guide.
How to Clean a Wood Deck
Clear the Deck Completely
Remove all furniture, planters, grills, and any items sitting on the deck surface. Move them to the yard or garage — you need unrestricted access to every board. See our outdoor furniture cleaning guide to clean those pieces separately.
Sweep and Blow Out Between Boards
Sweep the deck thoroughly, then use a putty knife or narrow stiff brush to clear debris trapped between boards. Leaves and dirt compacted between boards hold moisture and accelerate rot — clearing them is as important as cleaning the surface.
Pre-Wet the Deck
Spray the entire deck with a garden hose. Wet wood absorbs cleaning solution more evenly and prevents the cleaner from drying in patches. This is especially important on hot, sunny days.
Apply Oxygen Bleach Solution
Mix oxygen bleach per package directions — usually about 1 cup per gallon of warm water. Apply generously across the deck surface using a pump sprayer or brush. Let it dwell for 10–15 minutes. Oxygen bleach kills mold, algae, and mildew spores while brightening the wood grain without the damage of chlorine bleach.
Scrub with the Grain
Using your stiff deck brush, scrub along the direction of the wood grain — never across it. Scrubbing against the grain raises wood fibers and creates a rough surface that collects more dirt going forward. Apply extra pressure on black or green stained areas.
Rinse Thoroughly
Rinse with a strong hose stream or pressure washer. Work from the house outward so you’re always rinsing dirty water away from cleaned areas. Make sure all cleaning solution is completely rinsed — residue left on wood can cause discoloration and prevent stain or sealant adhesion later.
Apply Deck Brightener (Optional)
If the wood looks gray or weathered after cleaning, apply an oxalic acid-based deck brightener. It restores the warm, golden tone to weathered wood. Rinse after 15 minutes and allow to dry.
Dry Before Sealing
Allow the deck to dry completely — at least 48 hours in warm, dry weather — before applying stain or sealant. Applying over damp wood traps moisture and causes premature peeling.
How to Clean a Composite Deck
Composite decking is more stain-resistant than wood but can develop mold and mildew in shaded or damp areas. The key difference: use gentler cleaners and lower pressure.
Sweep and Clear
Remove all debris. Composite boards don’t need a hard sweep — a soft broom is sufficient. Check your composite manufacturer’s guidelines — some brands void warranties if pressure-washed above a specific PSI.
Mix Soapy Water and Apply
Warm water and dish soap (2 tablespoons per gallon) handles most routine cleaning. Apply and let dwell 5 minutes. For heavier buildup, use a dedicated composite deck cleaner.
Scrub Gently
Use a soft-to-medium bristle brush on composite — stiff bristles can scratch the surface finish. Scrub with the board grain direction.
Treat Mold or Mildew
Spray a diluted white vinegar solution (1:1 with water) on any mold spots. Let it sit 10 minutes and scrub. If mildew smell persists after cleaning, our mildew odor guide covers follow-up treatment.
Rinse and Dry
Rinse thoroughly with a garden hose or low-pressure washer (under 1,200 PSI). Allow to air dry before replacing furniture.
How to Remove Common Deck Stains
Tannin stains (dark streaks from leaves or iron furniture): Apply oxalic acid solution to the stain, scrub, let sit 10 minutes, then rinse. This is also effective for rust stains from metal furniture or nail heads.
Grease and oil: Apply dish soap directly to the stain, work it in with a scrub brush, and let sit 15–20 minutes before rinsing. For composite decking, baking soda paste applied to fresh oil stains works well.
Black mold: Oxygen bleach solution (for wood) or diluted white vinegar (for composite) and firm scrubbing handles most black mold. For persistent cases, the treatment is the same as our mildew removal walkthrough.
Pro Tips for Deck Maintenance
- Clean before the season: A spring deep clean removes winter’s accumulated grime and prepares the surface for sealant if needed. A quick fall sweep prevents leaves from decomposing on the surface over winter.
- Seal every 1–3 years: Unfinished wood decks benefit from annual sealing in humid climates, every 2–3 years in dry climates. Look for water to bead on the surface — when it soaks in instead, it’s time to reseal.
- Place furniture pads under legs: Metal furniture feet scratch composite and dent soft wood. Rubber feet caps or felt pads prevent marking and hold back rust transfer from wet metal.
- Combine with a full outdoor cleaning day: While the deck is drying, clean your patio pavers and porch for a complete outdoor refresh.
Frequently Asked Questions
What is the best thing to clean a deck with?
Oxygen bleach mixed with water is the best cleaner for wood decks — it kills mold and mildew without damaging wood fibers. For composite decks, warm water and dish soap handles most situations. Dedicated deck cleaning products from hardware stores also work well for both types.
Can I use a pressure washer to clean my deck?
Yes, with caution. Keep pressure under 1,500 PSI for wood and under 1,200 PSI for composite decking. Hold the nozzle at least 8–12 inches from the surface and keep it moving. Going too slow or too close raises wood grain and can permanently damage composite finishes.
What is the best homemade deck cleaner?
Mix 1 gallon warm water, 1 cup oxygen bleach powder, and 2 tablespoons dish soap. This handles mold, mildew, and general grime effectively on wood decks. For composite, just dish soap and water is usually all you need.
How often should I clean my deck?
At minimum, once a year with a deep clean. Twice per year (spring and fall) is ideal for maintaining the finish and preventing long-term damage. Spot clean stains and spills immediately when they happen to prevent them from setting.
How long should a deck dry before applying stain or sealant?
At least 48 hours of dry weather after a full wash. Check by splashing water on the wood — if it beads up, the wood is still too wet. If it absorbs immediately, it’s ready to seal. In humid climates, allow 72 hours to be safe.
Conclusion
A properly cleaned deck looks better, lasts longer, and is safer to walk on. Wood decks need the oxygen bleach treatment to kill mold and restore color; composite decks need gentler soap and lower pressure. Either way, a yearly deep clean and periodic sealing is the most effective maintenance routine you can do. When you’re ready to tackle the whole outdoor area, check out our pressure washing tips guide for the best technique on driveways, siding, and fences.
