Composite decking is best cleaned with a mild oxygenated cleaner or dish soap solution, a soft nylon brush, and a garden hose or pressure washer set to 1,500 PSI or less.
What You Need to Clean Composite Decking
The right tools and conditions matter more than elbow grease. Gather these before you start:
- Leaf blower or broom for clearing debris
- Oxygenated cleaner or warm water with mild dish soap
- Soft-bristle or nylon brush (no metal bristles ever)
- Garden hose or pressure washer set to ≤1,500 PSI with a fan-tip nozzle (40–60 degree spread)
- Temperature above 55°F, no rain or wind in the forecast
The Two Main Cleaning Methods
Method 1: Pressure Washer Route
Use this for larger decks or heavy grime, but keep the pressure low. Most brands cap the safe limit at 1,500 PSI; Envision Outdoor Living says 1,000 PSI max and requires a fan-tip nozzle. Here is the sequence TimberTech recommends:
- Clear and sweep the surface completely.
- Prepare the washer with a composite-safe cleaner per the manufacturer’s mixing ratio.
- Apply at the lowest pressure setting from at least 12 inches away.
- Let the cleaner dwell for 3–5 minutes (unless your brand says otherwise—TimberTech says 30–60 seconds). Do not let it dry.
- Rinse at high pressure from a minimum of 2 feet away, moving with the grain.
- Air dry. Keep pets and people off until it’s dry.
Method 2: Manual Scrub Route
Safer for small decks, stubborn spots, or when you don’t own a pressure washer.
- Remove furniture, sweep away debris, and give the deck a warm-water rinse.
- Mix 1 part oxygenated cleaner (or mild dish soap) with 20 parts warm water.
- Scrub in sections using a medium-stiffness nylon brush, working along the wood grain.
- Let the solution sit for 3–5 minutes (or 30–60 seconds per TimberTech’s guide), then rinse thoroughly with a garden hose.
- Repeat for any remaining stains.
What to Avoid on Composite Decking
- Chlorine bleach or sodium hypochlorite — lightens or yellows the deck color. Trex, Cali, NewTechWood, and TimberTech all warn against it.
- Strong chemicals like SLR or sugar soap — can etch or discolor. Cali explicitly bans them.
- Metal-bristle brushes — scratch and leave rust streaks.
- Pressure over 1,500 PSI, or closer than 6–12 inches — erodes the wood-plastic composite surface.
- Letting cleaner dry on the deck — leaves a residue that stains.
Brand-Specific Tips at a Glance
| Brand | Key Rule | Cleaner |
|---|---|---|
| Trex | Warm soapy water only; soft-bristle deck brush | Mild dish soap |
| TimberTech | Dwell time 30–60 seconds; rinse then dry with cotton cloths or leaf blower | Oxygenated cleaner |
| NewTechWood | Nylon brush; vinegar/baking soda for mold | Oxygenated or vinegar/baking soda |
| Envision Outdoor Living | 1,000 PSI max; fan-tip nozzle required | Oxygenated cleaner |
| Cali | Soft non-metal brush; no bleach, SLR, or sugar soap | Mild soap and water |
The universal rule across all brands: always check your specific manufacturer’s instructions and do a test spot before cleaning the whole deck.
FAQs
Can I use vinegar to clean composite decking?
Yes, but only for spot-treating mold or mildew. NewTechWood recommends a 50/50 vinegar and baking soda paste for that purpose. For general cleaning, an oxygenated cleaner or mild dish soap works better and rinses cleanly.
How often should I clean composite decking?
Once or twice a year is usually enough, depending on shade, tree cover, and local weather. Spring and fall are ideal because temperatures stay above 55°F. A quick mid-season hose-down can keep surface dirt from building up between deep cleans.
Will pressure washing void my deck warranty?
It can, if you exceed the brand’s PSI limit or nozzle distance. Most composite manufacturers set a safe ceiling of 1,500 PSI and a minimum distance of 12 inches. Use a fan-tip nozzle and never let the spray linger in one spot. Check your warranty terms before firing up the washer.
References & Sources
- TimberTech. “How to Clean Composite Decking.” Official 5-step cleaning guide with dwell times and drying instructions.
- Simple Green. “Composite Deck Cleaning Tips.” Recommends oxygenated cleaner, fan-tip nozzle, and 2-foot rinse distance.
- NewTechWood. “How to Clean Composite Decking.” Covers vinegar/baking soda for mold and nylon brush requirements.
Mo Maruf
I created WellFizz to bridge the gap between vague wellness advice and actionable solutions. My mission is simple: to decode the research and give you practical tools you can actually use.
Beyond the data, I am a passionate traveler. I believe that stepping away from the screen to explore new environments is essential for mental clarity and physical vitality.