To clean a wood deck, clear it, sweep it, then scrub with oxygen bleach along the grain. Rinse well and let it dry for 48 hours before sealing.
Sounds simple, and it mostly is. But our long winters and damp springs leave decks grey, slick, and full of mildew. Get the method wrong, and you can fade the boards or gouge them. Get it right, and you add years to your deck while keeping it safe underfoot.
Read on for the full step-by-step, the stains to watch for, and what it costs.
Why Cleaning Your Wood Deck Matters
A clean deck lasts longer and stays safer. Dirt, pollen, and wet leaves trap moisture against the boards. Trapped moisture is the top cause of wood rot.
Newmarket weather makes this worse. Our damp springs and humid summers feed algae, mould, and mildew. Shaded decks stay wet for days. That green film also gets slippery, which is a real hazard with kids around.
Regular cleaning clears all that out. It also preps the wood for stain or sealer down the road. Think of it like brushing your teeth. Skip it long enough, and you’re facing a bigger, costlier repair.
How to Clean a Wood Deck: Tools and Supplies You’ll Need
You probably have half this gear in the garage already. Round it up before you start:
- A stiff bristle deck brush with a long handle
- A garden hose with a spray nozzle
- A broom for sweeping
- A putty knife for the gaps between boards
- A plastic tarp to protect plants and siding
- Oxygen bleach or a quality deck cleaner
- A bucket for mixing
- Rubber gloves and eye protection
Step 1: Clear and Prep the Deck
Start with a bare surface. Pull off all furniture, planters, the BBQ, and any rugs. Don’t try to work around them.
Next, look around the edges. Trim back branches, vines, or bushes touching the deck. Then sweep off every leaf and bit of debris. Leaving organic material on the boards traps moisture and causes rot.
Now grab your putty knife. “Floss” out the gunk packed between the deck boards. Those gaps need to drain freely. Finally, cover nearby plants and garden beds with your tarp.
Step 2: Inspect for Damage Before You Clean
Look your deck over before you wet it. Cleaning won’t fix structural problems, and it’s smart to catch them early.
Check for loose, raised, or splintered boards. Press on soft spots; spongy wood usually means rot. Test the railings, posts, and balusters for wobble; a loose rail is a safety risk worth fixing or rebuilding right away. Then look underneath for loose fasteners or rot in the frame.
Found bad boards or a shaky frame? That’s beyond a simple clean. It may be time to replace those boards or rebuild the section before someone gets hurt.
Step 3: Choose the Right Deck Cleaner
The right cleaner does the work without wrecking your wood. You’ve got three solid paths and one to skip.
i) Oxygen Bleach
Oxygen bleach is the gentle but powerful choice. It lifts mildew and grime without harming the wood, plants, or pets. It breaks down into oxygen and soda ash, so it’s safe around your garden.
It’s also a real fungicide. That makes it great for the deep organic growth our climate breeds. Mix two gallons of warm water with two cups of oxygen bleach. Stir until it dissolves.
ii) Commercial Deck Cleaner
Store-bought deck cleaners work well and save mixing time. Most use the same active ingredient as oxygen bleach anyway. They’re less harsh on wood than high pressure washing and help preserve the boards. Just follow the label directions.
iii) DIY Vinegar and Soap Solution
Want to use what’s in the cupboard? Mild dish soap and warm water handle light dirt fine. Vinegar can brighten too, but go easy. Left to soak in or used undiluted, vinegar leaches colour out of the wood. Always test a hidden patch first.
Note:
Don’t reach for household bleach. It looks tempting, but it’s a trap. Chlorine bleach won’t kill mould spores, so the mould returns, and it harms your plants. It also breaks down wood fibres and corrodes your metal fasteners.
Read More: Pros and Cons of Composite Decking: Is It Worth It?
Step 4: Wet, Apply, and Scrub
Rinse the whole deck with your hose first. A damp surface absorbs cleaner better than a dry one.
Now apply your solution in sections. Don’t let it dry out before you scrub. Let it sit for 10 to 15 minutes to break down dirt and mildew.
Then scrub with a stiff bristle brush. Always work along the grain, never across it. Put extra muscle into stained, grimy spots. On softwoods like cedar, scrub gently to avoid raising the fibres.
Step 5: Brighten the Wood
Cleaner can leave the wood looking dull or slightly grey. A deck brightener fixes that. It restores the natural tone and balances the wood’s pH after cleaning.
Most brighteners use oxalic acid. Brush the solution over the whole surface for even colour. This step matters most if you plan to stain. Brightening helps stain and sealer adhere properly.
Step 6: Rinse Thoroughly
Rinse each section well once you’ve scrubbed it. Cover the boards, railings, and stairs.
Leftover cleaner leaves streaks and film when it dries. So give it a few passes with clean water. Keep the dirty water moving; don’t let it pool back into the wood.
Step 7: Let It Dry Completely
Patience pays off here. The surface may feel dry in hours, but the wood underneath needs longer.
Wait a full 48 hours before staining or sealing. Seal too soon, and you trap moisture inside the boards. That defeats the whole job. Want to test it? Drop a little water on a board; if it beads, the wood’s still too wet.
Read More: Deck Stain vs Deck Paint: Pros, Cons & Best Uses
How to Remove Common Wood Deck Stains
Different stains need different fixes. So before you scrub, match the cure to the cause; that’s what makes them lift fast. Here’s what you’re dealing with.
1. Mold and Mildew Stains
You’ll know mould by the black or grey speckles that smear when you wipe them. For these, reach for oxygen bleach, not the chlorine stuff. It’s a real fungicide, so it kills the spores hiding down in the wood pores.
Chlorine, on the other hand, only bleaches the colour away, which means the living spores creep right back. So soak the patch about 15 minutes, scrub along the grain, and rinse.
2. Algae and Moss Growth
Algae is that slick green film that turns your deck into a slip hazard. Moss, meanwhile, is the spongy stuff wedged in the gaps. Both thrive on trapped damp, and our shaded backyards hand it to them all spring.
That’s why ground level decks and pool decks catch it worst. The same oxygen bleach lifts it, but don’t stop at the surface; dig the moss out of the gaps too, since that’s where it takes root.
3. Grease and Food Stains
We’ve all dripped burger fat off the BBQ. The trouble is, grease soaks in as an oil, so acids and bleaches just slide off it.
Instead, catch it fast: blot the spill, then pour on very hot water to loosen the oil. From there, scrub with dish soap or a degreaser, which actually break the grease apart. And if it’s been there a while, expect to go over it twice.
4. Rust Stains
See a dark halo creeping out from a nail head or a planter foot? That’s rust, and here’s the frustrating part. The iron reacts with the wood’s own tannins, so the stain sits deep inside the fibres.
Because of that, you can scrub till your arms ache and nothing happens. Oxalic acid is the trick instead; it turns that iron compound colourless. Just brush it on, give it a few minutes, then rinse well.
5. Tannin Stains from Leaves
Leave a pile of wet leaves sitting too long and you’ll find brown rings underneath, especially on cedar. They look like water marks, yet no amount of washing shifts them. Luckily, oxalic acid dissolves them, same as it does rust.
The trick is to coat the whole board rather than just the ring, so the colour evens out. Better yet, sweep those leaves off weekly and you skip the problem entirely.
6. Bird Droppings and Organic Debris
Bird droppings are acidic, and left to bake in the sun they’ll etch right into your finish. So lift the solids with a plastic scraper first, and resist the urge to grind them in.
Once that’s done, treat the spot with oxygen bleach and rinse. As with every stain here, the quicker you get to it, the less it leaves behind.
Read More: Composite Decking Prices: Materials, Labour & Hidden Costs]
Can You Pressure Wash a Wood Deck?
Yes, but only if you’re careful and know what you’re doing. A pressure washer is quick, but it damages more wood decks than almost anything else. So before you start, here’s the full picture.
When Pressure Washing Is Appropriate
Pressure washing works well on heavily soiled or large decks, where hand-scrubbing would take all weekend.
It’s also safe on composite decking, since those boards handle the pressure without trouble. On solid wood, though, treat it as a last resort rather than your first move. For most homeowners, a brush and oxygen bleach give a safer and better result.
Risks of Improper Pressure Washing
Too much pressure gouges the wood. Worse, it raises the fibres and leaves the surface looking fuzzy and rough. And once you carve a line into a board, there’s no fixing it; that mark stays for good.
In bad cases, the only solution is to replace the damaged boards, which turns a simple cleaning into a repair job.
Recommended PSI Settings for Wood Decks
If you do use a washer, keep the pressure low. Stay under 1,500 PSI and fit a wide, 40 degree fan tip to spread the spray. For soft cedar, go gentler still, since it marks easily. Around 500 to 600 PSI is the safe range there; anything higher lifts the grain.
Best Practices to Prevent Damage
Beyond the pressure setting, your technique is what protects the deck. Hold the wand at least a foot above the boards, and keep it moving the whole time; pausing in one spot is what causes gouges. Always spray along the grain, never across it. And test a hidden corner first.
If all this feels like too much risk on a deck you’d rather not damage, our deck cleaning and restoration team can handle it for you. Otherwise, just avoid working in direct sun, since the cleaner will dry before you can rinse it off.
What Is the Best Time of Year to Clean a Deck in Newmarket?
In Newmarket, late May through June is the best time to clean a wood deck. The spring frost has passed, the pollen has settled, and the boards finally have time to dry.
Early fall is your second window, ideally September, before the leaves drop. Either way, pick a mild, dry day above 10°C, since most cleaners stall in the cold and the wood needs warmth to dry.
Aim for twice a year as a rule; our humid summers grow mildew while road salt and freeze-thaw winters wear the boards down. A covered deck stays drier through it all, so it needs cleaning less often.
How Much Does It Cost to Clean a Wood Deck?
Cleaning a wood deck in the Newmarket area costs about $50 to $150 if you do it yourself, or roughly $150 to $400 to hire a local pro for an average deck.
Of course, the final price depends on your deck’s size, condition, and whether you add staining. Here’s how the numbers break down for our York Region homeowners:
| Option | Typical Cost | What’s Included |
| DIY clean | $50 – $150 | Oxygen bleach, brush, brightener |
| Pressure washer rental | ~$38/day + deposit | Equipment only, you do the work |
| Professional cleaning | $0.35 – $1.10 / sq ft ($150 – $400) | Labour, products, proper drying |
| Clean + stain combo | $1.50 – $4.00 / sq ft | Full prep, clean, and finish |
How Often Should You Reseal or Stain a Wood Deck?
Reseal or restain a wood deck every two to three years. Pressure treated boards often need it every one to two years, while cedar holds up closer to three. Sun, rain, and foot traffic all shorten that window.
So the two-to-three-year rule is a starting point, not a hard schedule. Across Newmarket, sun-baked and high-traffic decks need a fresh coat sooner. Let’s break down what really drives the timing.
How Often by Wood Type
Wood type sets the baseline. Pressure treated lumber soaks up weather, so it often needs a coat every one to two years to hold up. Cedar lasts a little longer thanks to its natural oils, but two to three years is still the safe window. Either way, the freeze-thaw winters and UV-heavy summers here wear finishes down faster than a milder climate would.
Common Mistakes to Avoid When Cleaning a Wood Deck
Avoid these and you’ll save yourself grief:
- Using chlorine bleach, which weakens wood and kills plants
- Cranking the pressure washer too high and gouging the boards
- Staining before the deck fully dries
- Scrubbing across the grain instead of along it
- Working in direct sun, so the cleaner dries too fast
- Using undiluted vinegar and fading the wood
- Skipping the damage inspection before you start
DIY vs Professional Wood Deck Cleaning
A basic clean is a great DIY win. If your deck is sound and just needs a refresh, grab a brush and spend a Saturday on it. You’ll save a few hundred bucks.
Call a pro when things get tricky. Soft or rotting boards, wobbly railings, and large or second-story decks all raise safety concerns. A pro also cleans, repairs, and seals in one trip, with no risk of gouging the wood.
At XP Decking, we’ve spent over 15 years building and restoring decks across Newmarket. If your cleaning project turns up bigger problems, our deck building team can repair or design a new one. Want a straight answer on whether it’s a clean, a repair, or a rebuild? Call us at (416) 333-2366 or get in touch for a free quote. We come right to your place.
Frequently Asked Questions
How often should I clean my wood deck?
Clean it once or twice a year. In Newmarket, a deep clean in late spring and a lighter one in early fall works best. Add a quick sweep weekly to keep debris off.
Can I use regular household bleach on my deck?
Better not to. Chlorine bleach weakens the wood, kills nearby plants, and lets mould return. Oxygen bleach does the job safely instead.
Will a pressure washer ruin my wood deck?
It can, fast. On wood, high pressure gouges the surface and raises the fibres. If you use one, stay under 1,500 PSI, use a wide tip, and keep moving. A brush is safer.
How long should I wait before staining after cleaning? Wait at least 48 hours. The surface dries faster, but the wood underneath holds moisture. Seal too early, and you trap that water inside.
What’s the best cleaner for a mouldy or algae-covered deck?
Oxygen bleach. It’s a strong fungicide that kills spores and lifts deep growth. Apply it, wait 15 to 20 minutes, scrub, and rinse.
Do I need to move furniture and cover plants?
Yes to both. You want a bare surface to clean well. Cover plants and garden beds nearby, since some cleaners can harm them.
My boards feel soft or spongy. Can I just clean those?
No. Soft, spongy wood means rot, and cleaning won’t fix it. Those boards need replacing. Give us a call at (416) 333-2366 so we can check it before it spreads.
