Deck washing questions, answered straight.

It is not recommended. The Western Red Cedar Lumber Association, the cedar industry's own trade group, advises against power washing cedar decks or any other cedar product: even at moderate pressure, a power washer can seriously damage the soft summer-growth grain, leaving a furry, washboard surface that no stain hides. Its recommended approach instead is scrubbing with warm soapy water, with a diluted household (oxygen-based) bleach solution reserved for mildew. If a contractor plans to pressure wash your cedar deck, ask why, and ask what pressure and nozzle they intend to use.

It depends on the brand and product generation, not a single yes or no. Composite decking care varies significantly across manufacturers: current-generation capped composite from major brands often explicitly permits pressure washing up to a stated PSI without voiding the warranty (Trex's current lines, for example, allow up to 3,100 PSI with a fan-tip nozzle), while older, uncapped composite generally does not and can be damaged by it. Check your own deck's manufacturer care guide before pressure washing rather than assuming either a blanket yes or a blanket no. A contractor who pressure-washes any composite deck without asking the brand or checking the warranty terms first is skipping a step that matters.

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.

No verified Niagara or Ontario figure for what this costs exists in any authoritative source, so this guide does not give one. Ask for a written, itemized quote from a local contractor, and a second one itemized the same way, so the two can be compared line by line.

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.

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.