Wood vs Composite Deck Care in Florida Humidity

That gray, slightly slick film on a Florida deck is mildew and algae, not age, and it shows up on wood and composite decking alike. The difference is what happens underneath the surface. Wood absorbs moisture and can rot if the growth is left long enough. Composite will not rot, but its textured wood-grain surface gives algae just as much grip as real wood does. Both need low-pressure cleaning, and both get damaged by the same mistake: someone reaching for a standard pressure washer at full blast, a mistake our complete guide to pressure washing in Florida covers in more depth, along with why shaded decks in particular regrow algae faster than sunnier ones.

Waterfront properties along the St. Johns River near DeBary, where morning fog keeps decks damp well into the day, see this faster than most. Here is how wood and composite differ once you actually get into cleaning them.

Wood Decks: The Splinter Risk

Pressure-treated pine, cedar, and hardwood decks all collect mildew in Florida’s year-round humidity. The soft grain in pressure-treated lumber is especially vulnerable to splintering if it takes too much pressure directly. Keeping the pressure low and letting a cleaning solution do the heavy lifting gets the surface clean without tearing into the wood. If a wood deck has gone two or more years without cleaning, there is usually a surprising amount of original color hiding under that gray layer once it comes off.

If you are planning to restain afterward, cleaning is the necessary first step. Old mildew and degraded stain both need to come off before a new coat can bond. Once the deck is fully dry, typically 24 to 48 hours depending on weather, the surface is ready for stain. The North American Deck and Railing Associationrecommends professional cleaning before any refinishing work, because that’s what lets the new finish bond properly and actually last.

Composite Decks: Rot-Resistant, Not Maintenance-Free

Composite decking (Trex and similar brands) does not absorb water the way wood does, so it will not rot or splinter. That leads a lot of homeowners to assume it needs no maintenance at all. In practice, the same textured surface that gives composite its wood-grain look also traps algae spores just as effectively as real wood grain does. Trex’s own care guide recommends periodic cleaning with appropriate solutions and low pressure, and manufacturer warranties can be affected by improper cleaning methods like wire brushes or high-pressure blasting, which strip the protective cap layer instead of just the dirt on top of it.

Wood vs Composite: A Quick Comparison

Can You Clean a Deck with a Pressure Washer?

Yes, but not at the pressure most people picture when they hear the term. Concrete gets up to 3,000 PSI, and pointed straight at deck boards, that will splinter the grain, gouge soft wood, and strip stain right off the surface. Composite doesn’t rot, but the same high-pressure blast can strip its protective cap layer too, and that affects the manufacturer warranty.

We keep the pressure washer in the mix, just dialed right down, with a deck-safe cleaning solution doing the work of breaking down mildew and algae first. The low-pressure rinse then washes away what the solution already loosened. That’s the difference between a deck that comes out clean and one that needs new boards.

Why Florida Decks Need Cleaning More Often

In Central Florida, humidity, daily summer rain, and warm temperatures let mildew, algae, and mold take over any outdoor surface far faster than they would in a drier climate. Decks under tree canopy or on the shaded side of a house get hit worst and need attention first. Docks and piers along Volusia County waterways take the same beating, plus direct water exposure, and typically need the same low-pressure treatment adjusted for heavier buildup.