How Do I Clean Composite Decking?
Quick Answer: For routine cleaning, sweep off debris and wash composite decking with warm water and dish soap, scrubbing with a soft-bristle brush. Rinse thoroughly. For mold, mildew, or organic staining, use a composite-specific cleaner following the manufacturer’s recommendations. Avoid wire brushes, abrasive cleaners, bleach-heavy products, and – on most products – high-pressure power washing. Annual spring cleaning is the most important maintenance event for composite in Illinois.
Routine Cleaning: The Simple Version
Composite decking is genuinely easy to clean. For most routine maintenance:
- Sweep or blow off debris, leaves, and loose dirt
- Wet the surface with a garden hose
- Apply a solution of dish soap and warm water or a composite-approved cleaner
- Scrub with a soft-bristle brush in the direction of the board grain
- Rinse thoroughly with the hose
That’s it. No sanding, no stripping, no staining. This is the maintenance difference that makes composite worth the cost for most Fox Valley homeowners.
Spring Cleaning: The Annual Priority
After an Illinois winter, your composite deck needs a proper cleaning before patio season starts. The combination of sand tracked onto the deck for traction, pollen that settles in spring, and any organic debris that wasn’t cleared in fall can stain the surface if left.
Spring cleaning is the same process as routine cleaning, just more thorough. Pay attention to the gaps between boards – debris compacts there over winter and should be cleared out. A deck cleaning tool with thin tines works well for this, or a flat plastic or wood tool. Avoid metal.
Dealing With Specific Stains
Grease from grilling: Clean immediately with soap and warm water. Set grease is harder to remove. A composite-specific degreaser handles older grease stains. Using a grill mat under the grill prevents this problem.
Mold and mildew: Very common on shaded Illinois decks. Use a composite-approved mold and mildew cleaner. Apply per instructions, dwell, scrub with a soft brush, rinse. For persistent mold, a second application usually clears it. More about mold on Illinois composite decks.
Tannin staining (from leaves): Brownish stains from wet leaves sitting on the deck. Composite-approved cleaners handle most tannin staining. Prevent it by clearing leaves promptly in fall.
Rust stains (from metal furniture): Composite-approved rust removers can help. The key is acting promptly – fresh rust stains are much easier to remove than old ones.
Bird droppings: Clean promptly. They’re acidic and can etch surfaces over time.
What to Avoid
Wire brushes or steel wool: Will scratch the board cap.
Abrasive cleaners: Scratch the surface.
Bleach-heavy products: Can discolor composite and damage the cap. Some cleaning products marketed as mold killers contain bleach concentrations that violate composite warranties. Check your product’s warranty for approved cleaner lists.
Pressure washing (with caution): Some manufacturers permit pressure washing at low settings (typically under 1500 PSI with a fan tip held 8 or more inches from the surface). Others prohibit it entirely. Check your specific product’s warranty and installation documentation before using a pressure washer. Using too high a pressure or too narrow a nozzle will damage the cap.
Important Considerations
Check your warranty for approved cleaners. Many composite manufacturers specify which cleaning products are approved and which void the warranty. This is worth knowing before you reach for whatever’s under the kitchen sink.
Clean before treating any issue. Before assuming a stain is permanent, try a thorough cleaning with an appropriate product. Most stains that homeowners think are permanent come out with the right cleaner and technique.
Composite doesn’t need sealing or staining. The cap is the protection. No additional products are needed or appropriate for sealing or staining composite. Can composite decking be painted or stained? – the answer is no, and here’s why.
What to Do Next
If your composite deck needs professional cleaning or you have staining that routine cleaning hasn’t addressed, call DDT Deck Builders at 630-200-3945. We can assess whether cleaning will resolve the issue or whether something structural is contributing to the problem.
We serve Oswego, Aurora, Montgomery, Yorkville, Plainfield, and Kane and Kendall County.