Professional Deck Cleaning
in Seattle & the Eastside
Gray, weathered wood, moss, and mildew steal years from your deck. We clean cedar, pressure-treated, and composite decks with the low-pressure, grain-safe method wood actually needs — and prep the surface for staining if that's your next step.
Why Seattle Decks Gray, Stain & Grow Moss
A wood deck faces constant assault in the Pacific Northwest — moisture, UV, tree debris, moss, algae, and mildew all working against it year-round. Without regular cleaning, wood grays, stains, and deteriorates far faster than it should.
That gray, weathered look is oxidized wood fiber. The dark blotches and black spots are mildew and tannin staining — tannins are natural compounds in cedar, redwood, and other woods that leach out and darken the surface, especially where leaves and debris sit. Left long enough, moss and algae take hold in the damp, shaded areas and start breaking the surface down.
The good news: almost all of this is reversible with the right approach. A professional cleaning doesn't just make a deck look new again — it removes the growth and staining that shorten a deck's life, and sets the stage for a stain or seal that will protect it for years.
How We Clean Decks — The Grain-Safe Way
Wood is not concrete. Over-pressuring is the number-one way DIY deck cleaning goes wrong — raised grain, a fuzzy surface, gouged boards. Our method is built around protecting the wood.
Wood Type & Condition Assessment
We identify the material — cedar, redwood, pressure-treated, or composite — and its condition, then set pressure well below what hard surfaces take. Softwoods like cedar get the gentlest settings of all.
Oxygenated Cleaning
We apply an oxygenated (sodium percarbonate) cleaner that lifts mildew, algae, and grime — effective, and safer for surrounding plants than harsh chlorine. Heavy moss or mildew gets a pre-treatment dwell to break it down first.
Low-Pressure, With the Grain
We clean at low pressure with a wide-angle tip held off the surface, always working with the grain — never a spinning surface cleaner that goes across it and damages the wood.
Brighten & Prep for Finish
We finish with an acidic wood brightener that dissolves tannin and rust stains, restores natural color, and neutralizes pH so the wood is perfectly prepped to accept stain or sealer evenly.
Wood & Deck Surfaces We Clean
From cedar decks to composite railings, we clean every kind of exterior wood surface:
Cedar Decks
The most common — and most delicate — deck wood here. Very low pressure and the right chemistry remove gray and mildew without raising the grain.
Pressure-Treated Wood
More durable than cedar but still needs controlled pressure. We clean off years of graying, mildew, and tannin staining.
Redwood
Rich in tannins that leach and darken over time. Our clean-and-brighten process restores its natural warmth.
Composite & PVC
Doesn't rot, but still grows mold and algae in the shade. Cleaned gently at low pressure to remove growth without marring the surface.
Railings, Stairs & Pergolas
The details — balusters, steps, railings, arbors, and pergolas — cleaned along with the deck for a consistent result.
Docks & Wood Retaining Walls
Wooden docks, boat ramps, and retaining walls cleaned of the algae and slick growth that make them hazardous.
Deck Problems We Solve
Gray, Weathered Wood
Oxidized surface fiber cleaned and brightened back to the wood's natural color.
Tannin & Rust Stains
The dark leaf-and-debris staining and metal rust marks dissolved with an acidic brightener, not scrubbed in.
Mildew & Mold
Lifted with oxygenated cleaner that's effective and gentler on your landscaping than chlorine.
Moss & Algae
The slick green growth in shaded, damp areas removed before it breaks down the surface — and makes the deck a slip hazard.
Staining & Sealing Prep
Cleaned, brightened, pH-neutralized, and grain-opened so your stain or sealer absorbs evenly and lasts.
No Fuzzy, Damaged Wood
The low-pressure, with-the-grain method avoids the raised grain and gouging that ruin DIY deck jobs.
Our deck and driveway were covered in moss and green algae — embarrassing, honestly. Now they look absolutely brand new. Professional service from inquiry to completion.— Kevin A., Newcastle, WA · Deck & Driveway Cleaning
What Does Deck Cleaning Cost in Seattle?
Deck cleaning cost depends on the size of the deck, the wood type and its condition, and whether you want a straight cleaning or a full clean-and-brighten prep for staining. We provide transparent, itemized quotes.
Deck Size & Surfaces
Total square footage plus railings, stairs, and adjacent structures determine scope. We measure for an accurate quote.
Wood & Condition
Heavy graying, deep tannin staining, or established moss need extra cleaning and dwell time, accounted for upfront.
Clean vs. Staining Prep
A clean-and-brighten prep costs a bit more than a straight wash but sets up a far better, longer-lasting finish.
The fastest way to an accurate price is a free quote. We respond within 24 hours — often same day.
Frequently Asked Questions
Can pressure washing damage my deck?
Yes — over-pressuring is the most common way decks get damaged. Too much pressure raises the wood grain, leaves a fuzzy surface, and gouges the boards. Softwoods like cedar are especially vulnerable. The fix is technique, not force: we use low pressure matched to the wood type, a wide-angle tip held well off the surface, and we always work with the grain, never against it.
How often should I have my deck cleaned in the Seattle area?
Every 1–2 years is right for most Pacific Northwest decks. Our damp, shaded climate grows mildew, algae, and moss quickly, and leaves and debris leave tannin stains and a gray, weathered look. If your deck is sealed or stained, cleaning on schedule dramatically extends the finish; if it's bare wood, annual cleaning keeps it in the best possible shape.
Will you prepare my deck for staining or sealing?
Yes — a professionally cleaned deck is the ideal candidate for stain or sealer. We remove mildew, graying, and surface contaminants, and finish with a wood brightener that neutralizes pH and opens the grain so the finish absorbs evenly. For best results, stain within a few days of cleaning, once the wood has dried below the moisture level a finish needs to adhere.
What removes the gray, weathered look from old wood?
That gray is oxidized, weathered wood fiber — and the black or dark blotches are usually mildew and tannin staining. We clean with an oxygenated (sodium percarbonate) cleaner that lifts mildew and grime, then apply an acidic brightener that dissolves tannin and rust stains and restores the wood's natural color. The two-step process is what brings gray wood back to life.
Do you clean composite decking too?
Yes. Composite and PVC decking still grow mold, mildew, and algae in shaded, damp areas — they just need a gentler approach than wood. We clean composite at low pressure with the appropriate solution to remove growth and staining without marring the surface.
Have a question we didn't answer? Call (425) 298-7041 or submit a quote request — we respond within 24 hours.
Ready to Restore Your Deck? Book the Right Service
Deck cleaning is delivered through our wood service — and pairs naturally with the surfaces around it:
Bring Your Deck Back to Life
Whether it's gray and weathered or covered in moss, we'll restore your deck safely — and prep it for stain if you're ready. Free, no-obligation quote for your Seattle or Eastside home, usually same day. We serve Bellevue, Kirkland, Redmond, Sammamish, Bothell, Newcastle, and surrounding communities.
✓ Licensed & Insured ✓ 5.0 ⭐ Google Rating ✓ Free Quotes in 24hrs ✓ 100% Satisfaction Guarantee
