Wood greys for a predictable reason: UV exposure breaks down the lignin in the wood, and the surface oxidizes. That greying is accelerated by mildew and algae growth, which feed on the organic material in the wood. Left alone, a deck goes from looking a few years old to looking like it's been out in the weather for a decade, even if it hasn't. The good news is that most of that deterioration is surface-level.
Pressure washing a wood or composite deck at the right pressure, low enough not to raise the grain and high enough to remove the buildup, brings the colour back noticeably. A deck that's been sitting grey for three years often looks substantially different after a single cleaning. People are regularly surprised by how much improvement is possible without any refinishing.
If you're planning to stain or seal the deck, cleaning first is not optional. It's the whole job. Stain applied to a dirty surface won't penetrate evenly. You'll end up with a blotchy finish that peels within a season or two. The cleaning is what allows the stain to bond properly with the wood. Skipping it means redoing the stain job far sooner than you should have to.
If you haven't had your deck cleaned in two or more years, there's a good chance it looks worse than it needs to.
Get a free quote→Composite decking has different requirements than wood. High pressure can damage composite surfaces, and some harsh cleaning chemicals void composite warranties. Low-pressure washing with the right cleaning solution handles composite well. If your deck is composite and a contractor shows up with a standard pressure washer and no discussion of pressure settings, that's worth questioning.
The timing matters. Clean a wood deck in spring before the sun gets strong, allowing the wood to dry slowly and evenly, which reduces the chance of cracking. If you're cleaning and staining in the same visit, mild spring weather is ideal. The stain needs to cure, and extreme heat can cause it to dry too fast and not penetrate properly.
