Clean and treat deck

Clean and optionally seal your deck to restore its appearance and protect the wood.

Why it matters#

Annual cleaning removes dirt, mold, and mildew that degrade wood. Sealing protects against UV damage and moisture, extending your deck's lifespan by years.

What you'll need#

Tools#

Stiff bristle brush or push broom
Garden hose with spray nozzle (or pressure washer on low setting)
Pump sprayer
Paint brush or roller (for sealer)

Materials#

Deck cleaner (commercial or DIY: 1 cup oxygen bleach per gallon of water)
Deck brightener (optional, for wood decks)
Deck sealer or stain (if sealing)
Plastic sheeting (to protect plants)

Steps#

1. Clear the deck#

Remove all furniture, planters, grills, and rugs. Sweep away loose debris, leaves, and dirt.

2. Protect surrounding plants#

Cover nearby plants with plastic sheeting to protect them from cleaning solution runoff.

3. Wet the deck surface#

Use a garden hose to thoroughly wet the entire deck surface. This helps the cleaner work better.

4. Apply deck cleaner#

Using a pump sprayer, apply deck cleaner evenly across the surface. Work in sections, following the product instructions for coverage.

5. Let the cleaner work#

Allow the cleaner to sit for 10-15 minutes (check product label). Don't let it dry completely.

6. Scrub the surface#

Use a stiff brush to scrub the deck boards, working with the wood grain. Pay extra attention to high-traffic areas and spots with visible mold or mildew.

7. Rinse thoroughly#

Rinse the deck completely with a hose or pressure washer on a low setting (under 1,500 PSI for wood). Work in the direction of the boards to push debris off.

8. Apply brightener (wood decks only)#

If using a wood brightener, apply after rinsing and let it work according to product directions. Rinse again.

9. Let the deck dry completely#

Wait 24-48 hours for the deck to dry fully before applying sealer or moving furniture back.

10. Apply sealer or stain (optional but recommended)#

Once dry, apply deck sealer or stain according to product directions. Use a brush, roller, or pump sprayer. Apply thin, even coats.

Pro tips#

Clean your deck annually; seal every 1-3 years depending on sun exposure and wear
The best time to clean is spring or early fall when temperatures are moderate (50-80°F)
Test pressure washer settings on an inconspicuous area first—too much pressure damages wood
Composite decks need cleaning but don't require sealing

Warnings#

Don't use chlorine bleach on wood decks—it can damage wood fibers and kill nearby plants
Pressure washers can damage soft wood if set too high—keep distance and use fan tip
Allow proper dry time before sealing—applying sealer to damp wood traps moisture

Consider hiring a professional deck cleaning service ($200-400) if you have a large deck, don't own a pressure washer, or want to ensure proper staining technique. Deck refinishing or repair (loose boards, structural issues) should always be done by a pro.