Wood is the easiest surface on a property to ruin with a pressure washer, and a furred, splintered deck is the most common way it happens. Proper deck and fence cleaning is chemistry first, low pressure second — in that order, always.
Why wood tears
Timber is not uniformly hard. Softwood decking alternates dense latewood grain with much softer earlywood, and a pressure stream erodes the soft bands far faster than the hard ones. Push too much pressure — or hold the tip too close — and you carve the soft grain out, leaving raised ridges, fuzz and splinters.
Once the grain is torn, washing cannot fix it. The repair is sanding, which on a full deck is a serious project. Prevention is the entire game.
The sequence that works
A percarbonate or hypochlorite-based deck cleaner goes on first and does the actual work: breaking down the grey oxidised surface layer and killing algae and mildew. After proper dwell time, a wide-fan, low-pressure rinse carries it all away — the water is transport, not the tool.
Badly greyed wood gets a brightener afterwards — usually oxalic acid — which neutralises the cleaner’s alkalinity and pulls the timber’s colour back toward fresh-cut. If staining is planned, the brightening step is not cosmetic: coatings bond poorly to alkaline wood.
Reading a deck before touching it
Board condition dictates everything. Sound timber takes the standard process; soft, spongy boards, popped fasteners and wobbling rails mean the deck needs a carpenter before it needs a cleaner.
Age matters too — older, weathered decks have less sound surface to spare, so pressure discipline gets stricter as the wood gets older.
If a previous wash already furred the surface, ask us to look — sometimes a brightener and light sand rescue it. Read more about deck and fence cleaning →