Every composite deck ad promises zero maintenance, and it's close to true compared to wood — no sanding, no staining, no annual sealing. But "low maintenance" isn't "no maintenance," especially a few miles from the Chattahoochee where summer humidity regularly sits above 80% and pine pollen coats every outdoor surface each spring. The good news is that keeping a composite deck looking new in Dunwoody really does come down to about 20 minutes of work, spread across a handful of sessions a year, as long as you're doing the right things and skipping the wrong ones.
Why Composite Still Needs a Little Upkeep Here
Composite boards are a blend of wood fiber and plastic, and while the plastic shell resists rot, it doesn't resist everything organic matter can do on top of it. Georgia's climate throws three things at a deck surface that plain vinyl siding never has to deal with: heavy spring pollen, high ambient humidity that keeps surfaces damp longer after rain, and shaded pockets under pergolas or tree canopy where moisture lingers. None of that damages the board itself, but left alone it turns into a dull, sometimes slick film that makes the deck look older than it is — and eventually into mildew growth in the grain texture of capped composite boards.
The Actual 20-Minute Routine
Weekly During Peak Pollen Season
From roughly late March through April, DeKalb County pollen counts spike hard enough to leave a visible yellow-green film on any flat outdoor surface within a day or two. A dry broom sweep or a quick rinse with a garden hose once a week keeps that film from building into a stain that needs scrubbing later. This step alone takes five minutes and prevents most of the harder cleaning most homeowners dread.
Monthly Rinse and Sweep
Outside of pollen season, a monthly sweep to clear leaves, dirt, and organic debris — especially from between boards and against railing posts — keeps moisture from sitting in one spot long enough to feed mildew. Pair it with a garden-hose rinse and you're done in under ten minutes.
Twice-a-Year Deep Clean
Spring and fall, give the deck a real cleaning: a soft-bristle deck brush, warm water, and a composite-safe cleaner (most manufacturers, including Trex and TimberTech, sell their own formulas, and a mild dish soap works in a pinch). Scrub with the grain, rinse thoroughly, and let it air dry. This is also the right time to check railings, fasteners, and any structural elements for the twice-yearly once-over, which pairs well with the seasonal walkthrough we cover in our deck permit guide for anyone adding to an existing structure.
Mold and Mildew: The Real DeKalb County Problem
Mildew is the single most common complaint we hear from composite deck owners in this area, and it's almost always a humidity-and-shade problem rather than a product defect. Boards that sit under heavy tree cover, next to a fence line that blocks airflow, or on the north side of a house that never gets direct sun are the ones that develop the telltale black speckling first. A vinegar-and-water solution (roughly one part white vinegar to three parts water) handles light mildew without harsh chemicals; for anything more established, a composite-specific mildew cleaner applied with a soft brush — never a wire brush, which can scuff the cap layer — clears it without damaging the surface.
Not Sure If It's Time to Repair or Just Clean?
If your deck needs more than a scrub — soft spots, fading past a normal cleaning, or boards that were never quite right — we'll give you a straight answer, not an upsell.
📞 Call 470-327-9145What Not to Do
Don't Pressure-Wash on High Settings
A pressure washer set above roughly 3,100 PSI, or held too close to the board, can etch the cap layer of composite decking, leaving permanent streaks that no cleaning fixes. If you use one at all, keep it under 3,100 PSI, use a fan tip, hold it at least a foot from the surface, and always spray with the grain — never straight down into the board.
Don't Reach for Bleach or Harsh Solvents
Straight bleach can discolor composite boards unevenly and break down the cap layer over time, and solvent-based cleaners can do the same to railing components. Stick to composite-manufacturer-approved cleaners or the mild dish soap and vinegar approach above.
Don't Ignore the Gaps Between Boards
Composite decking is installed with small gaps for drainage and expansion, and those gaps collect pine straw, seed pods, and dirt over a Georgia summer. A putty knife or a specialty gap-cleaning tool run through the gaps once or twice a year prevents standing water from pooling against the joists underneath — which is where real structural problems eventually start, not on the visible board surface.
When to Stop DIY-ing It
If a deep clean doesn't restore color, if boards feel soft or spongy near fasteners, or if railings have started to wobble, that's no longer a cleaning issue — it's worth a professional look. For a plain-language rundown of which composite product tier holds color and structure best under Georgia conditions in the first place, see our guide to decking brand tiers, and if you're still weighing composite against a traditional wood deck for a Dunwoody backyard, that comparison is worth a read before you build. We also install and service composite systems directly — details are on our composite & Trex decking page.