How can I clean and restore a wood deck?

You can clean and restore a wood deck by washing it with an oxygen-based cleaner, neutralizing with a brightener, allowing it to dry, lightly sanding any fuzz or rough spots, and finishing with a high-quality stain or sealer. Done right, this brings back color, removes grime and mildew, and protects the wood for seasons to come.

What You’ll Need

• Tools: stiff-bristle deck brush, pump sprayer, garden hose or pressure washer, random-orbit sander (5–6"), sanding pole/block, shop vac or leaf blower, putty knife, screwdriver/impact driver, hammer & nail set, painter’s tape, drop cloths/plastic sheeting
• Safety: eye protection, chemical-resistant gloves, hearing protection (if using power tools), N95 or P100 mask for sanding
• Materials: oxygenated deck cleaner (sodium percarbonate), wood brightener (oxalic acid), deck stain/sealer (semi-transparent is a great balance), replacement screws/nails, replacement boards (if needed)

Approximate costs: cleaner ($20–40), brightener ($20–30), stain ($35–70/gal; 200–300 sq ft/gal), pressure washer rental ($40–75/day), sander rental ($50–70/day). Time: 1 day to clean, 24–72 hours drying, 1 day to sand and finish.

Safety and Prep

• Protect plants and grass with plastic; pre-wet greenery before and after chemical use.
• Wear goggles and gloves when handling cleaners and brighteners.
• Disconnect or cover electrical outlets on/near the deck.
• Work on a cool, overcast day if possible to slow drying and prevent spotting.

Step-by-Step: Clean and Restore

1) Inspect and repair

• Tighten or replace popped fasteners; countersink nails using a nail set.
• Replace severely cracked or rotten boards. Minor splinters can be sanded later.
• Clear debris from gaps between boards with a putty knife.

2) Wet down the deck

• Rinse the deck and nearby surfaces with a garden hose. Pre-wetting keeps the cleaner from absorbing too fast.

3) Apply an oxygen-based cleaner

• Mix according to label in a pump sprayer. Spray generously on boards, rails, and steps.
• Let it dwell 10–15 minutes; don’t let it dry. Mist with water if needed.

4) Agitate

• Scrub with a stiff-bristle deck brush, following the grain to lift dirt, mildew, and old gray fibers.

5) Rinse (pressure washer optional)

• A garden hose with a nozzle works; a pressure washer speeds the rinse. Keep pressure moderate and move with the grain.

Pressure washing guidance
- Pressure: 500–1,200 PSI for softwoods (pine/cedar), up to ~1,500 PSI for harder woods
- Nozzle: 25° or 40° fan tip
- Distance: 8–12 inches from the surface
- Motion: steady, with the grain, overlapping passes

Avoid turbo nozzles; they carve wood.

6) Brighten/neutralize

• Apply a wood brightener (oxalic acid) with a pump sprayer. It evens out color, neutralizes the cleaner’s pH, and helps remove tannin/iron stains.
• Let sit per label (usually 5–10 minutes) and rinse thoroughly.

7) Dry and test

• Allow 24–72 hours of dry weather. Check for proper moisture before staining.

Staining window
- Wood moisture: ≤12–15%
- Temperature: 50–90°F
- Weather: 24 hours before and 24–48 hours after without rain

A cheap pin-style moisture meter helps. Without one, a bead of water that soaks in within a minute is a decent indicator.

8) Sand problem areas

• Lightly sand where there’s fuzzing, raised grain, or splinters: 60–80 grit on treads and deck boards; 100–120 grit on rails.
• Don’t over-sand; very fine sanding can seal the surface and reduce stain penetration. Vacuum or blow off dust.

9) Stain or seal

• Choose a penetrating semi-transparent stain for UV protection with visible grain. Oil-based penetrates deeply; water-based dries faster and is lower odor.
• Stir thoroughly (don’t shake). Apply with a stain brush or 3/8"–1/2" nap roller, then back-brush with the grain to even out.
• Work 2–3 boards at a time end-to-end to avoid lap marks. Wipe any puddles after 10 minutes.

10) Cure and maintain

• Light foot traffic after 24 hours (check product). Full cure often 48–72 hours.
• Clean yearly with a mild deck wash and soft brush; recoat every 2–3 years or as needed.

Tips for Best Results

• New pressure-treated lumber needs time to dry before finishing, often 3–6 months. Test for water absorption before staining.
• For black mildew spots, an oxygen cleaner is safer for wood and plants than household chlorine bleach. If you must use bleach on stubborn biological staining, dilute heavily (no more than 1:10 with water), avoid contact with metal/aluminum, and follow with a brightener.
• Keep the sun at your back while staining to see wet edges and avoid misses.
• Do railings first, then floor; drips on fresh floor stain are hard to fix.

Common Mistakes to Avoid

• Using too much pressure or a turbo nozzle: causes furring and divots.
• Skipping the brightener: leads to uneven color and poor stain adhesion.
• Staining over damp wood: traps moisture and causes premature failure.
• Over-sanding: reduces stain absorption and causes blotchiness.
• Applying a film-forming deck “sealer” on horizontal boards: tends to peel; use penetrating finishes.

When to Call a Pro

• Significant rot, loose framing, or wobbly railings indicate structural issues.
• Large decks with failing film finishes (paint/solid stain) may need stripping and drum sanding.
• High-end hardwoods (ipe, mahogany) benefit from pro cleaning and oiling to avoid streaks.
• If lead-based coatings are suspected on older painted components, hire a certified contractor.

Restoring a wood deck is a very doable project with the right approach: clean, neutralize, dry, touch up with sanding, and protect with a quality penetrating finish. Plan for a solid weekend plus drying time, and your deck will look great and last longer.