My deck is green and slippery in Niagara Falls. What is that?

Algae and mildew, fed by Niagara's damp lake-and-river air. It grows on shaded boards that never fully dry. A soft wash with the right solution kills and lifts it. High pressure only opens the grain for it to come back faster.

Deck washing questions, answered straight.

Q: Can you pressure wash a cedar deck?

You can, but not at high pressure. Cedar is soft and a narrow high-pressure tip carves the grain, leaving a furry surface no stain hides. The right approach is a low-pressure soft wash, roughly 500 to 600 PSI through a wide fan tip, with a wood-safe cleaner doing the lifting. Ask any contractor you are considering what PSI they use for cedar before booking.

Q: Should composite decking be pressure washed?

No. High pressure can dull the cap on composite and PVC, raise the texture, and void the warranty. Composite wants a dedicated composite cleaner and a gentle rinse, which is what the manufacturers recommend. Always ask what method and PSI a contractor plans to use on composite before they start.

Q: How much does it cost to wash a deck in Niagara Falls?

Deck washing is generally priced per square foot by material. Cedar and softwood soft wash illustratively runs $2.00 to $4.00 a square foot, composite $1.50 to $3.00, and pre-stain prep $2.50 to $5.00. A 300-square-foot cedar deck illustratively runs $600 to $1,000.

Q: When is the best time to wash a deck in Niagara Falls?

Late spring into early summer is ideal. You get the algae off before peak use and have a dry stretch ahead for staining. Niagara's damp lake air means the wood needs a genuine dry window. Washing too late in fall means the deck may never dry properly before winter.

The same handful of questions come up before most Niagara Falls deck washes. Here are the plain-language answers, including the honest version of what pressure is safe for cedar and why composite should never see a pressure washer.

Got a deck question in Niagara Falls? Start here.

Straight answers

Questions Niagara Falls homeowners ask about deck washing

See the cost guide for illustrative per-square-foot pricing by material.

Can you pressure wash a cedar deck?

You can, but not at high pressure. Cedar is soft, and a narrow high-pressure tip carves out the soft summer-growth grain from between the harder rings, leaving a furry, washboard surface that no stain hides. The right approach is a low-pressure soft wash, roughly 500 to 600 PSI through a wide fan tip held back from the surface, with a wood-safe cleaner doing the lifting. Done right, the board comes back smooth and even. Ask any contractor you are considering what PSI they use for cedar before booking.

Should composite decking be pressure washed?

No. High pressure can dull the protective cap on composite and PVC boards, raise the texture, and void the manufacturer warranty. Composite wants a dedicated composite cleaner and a gentle rinse, which is exactly what the board manufacturers recommend in their own care guides. A contractor who pressure-washes composite the same way they wash a concrete driveway is doing it wrong. Always ask what method and what PSI a contractor plans to use on composite before they start.

My deck is green and slippery. What is that?

Algae and mildew, fed by the damp lake-and-river air in Niagara Falls. It grows first on the shaded side that never fully dries, and that is what makes a deck slick underfoot in the morning. A soft wash with the right solution kills and lifts it. Blasting it with high pressure only knocks the surface growth off and opens the grain for it to come back faster. If your deck is in a spot that stays damp and shaded, a regular wash each season keeps it manageable.

How much does it cost to wash a deck in Niagara Falls?

Deck washing in Niagara Falls is generally priced per square foot by material. Cedar and softwood soft wash illustratively runs $2.00 to $4.00 a square foot, pressure-treated $2.00 to $3.50, composite $1.50 to $3.00, and full pre-stain prep $2.50 to $5.00. A typical 300-square-foot cedar deck wash illustratively runs $600 to $1,000. Full illustrative ranges are in the cost guide.

Do I need to clean my deck before staining it?

Yes, and it is the step that decides whether the stain lasts. Stain needs clean, evenly-toned, properly dry wood to bond to. The correct prep is three steps: soft-wash cleaning, a wood brightener to neutralize the cleaner and open the grain, and then a real dry window before any stain goes on. Skipping the brightener means the stain sits on the surface instead of soaking in. Staining over damp wood is the number-one reason a deck stain peels by the next summer.

When is the best time to wash a deck in Niagara Falls?

Late spring into early summer is the ideal window. You get the algae off before peak use, and if you are planning to stain, you have a dry stretch ahead of you. Niagara's damp lake air means a deck holds moisture longer than inland, so the wood needs a genuine dry window after the wash, not just a day between showers. Washing too late in the fall is risky: daytime temperatures drop and the wood often stays too damp to dry properly or take a stain before winter. If you are planning to stain, aim to get the wash done by early July at the latest.

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Hiring a deck washing service in Niagara

Before any work starts, confirm the service carries liability insurance and WSIB coverage. Ask for references and, where possible, names of specific neighbourhoods in Niagara Falls where they have worked. A contractor who cannot confirm local experience is worth screening carefully before booking.

Ask for a written estimate that states the deck material, the square footage being washed, and the pressure and solution approach planned. Vague quotes leave room for add-ons after the crew is already on site, and the cleaning method matters as much as the price.

Ask the technician whether they soft-wash or pressure-wash, and what PSI they use by deck material. Cedar and softwoods want roughly 500 to 600 PSI through a wide fan tip, not a turbo nozzle that fuzzes the grain. Composite and PVC should not see a pressure washer at all, high pressure can void the manufacturer warranty. A contractor who gives a single pressure for every deck material is worth asking more questions before handing over your boards.