Composite decking is designed to be low maintenance — but low maintenance doesn't mean no maintenance. Algae, mould, and organic staining still accumulate on composite surfaces, and improper cleaning can void manufacturer warranties or damage the surface texture.
Why Composite Cleaning Is Different
Wood decking can handle significant pressure washing force because solid wood fibres are forgiving. Composite decking has a precision-manufactured surface texture over a wood fibre and polymer substrate. High-pressure washing can erode this texture, create fuzzing, or strip the protective cap layer on capped composite products — permanently changing appearance and increasing susceptibility to future staining.
What Cleaning Products Work on Composite
Most composite manufacturers (Trex, TimberTech, Fiberon, Deckorators) approve mild dish soap and water, dedicated composite deck cleaner, or diluted white vinegar for regular cleaning. Diluted sodium hypochlorite is generally acceptable at low concentrations for mould and mildew — check your specific product's warranty documentation first.
Avoid oil-based cleaners, abrasive products, steel wool, solvents, and high-concentration bleach. Never use deck brighteners or wood stripping products on composite — these are intended for natural wood chemistry.
Check Your Warranty: Before using any cleaning product, check the manufacturer's care guide. Using an unapproved product can void the material warranty.
Pressure Washing Composite: Safe Settings
Keep pressure below 1,500 PSI and use a 40-degree fan tip, maintaining at least 12 inches from the surface. Always spray with the direction of the grain pattern — never across it. For most composite decking, a garden hose with a spray nozzle or light-duty pressure washer at low settings is sufficient.
Treating Mould and Mildew on Composite
Treat with a composite-approved cleaner or diluted sodium hypochlorite (1/4 cup bleach per gallon of water). Apply with a soft brush, allow to dwell 5–10 minutes, and rinse thoroughly with low-pressure water. For stubborn growth in textured grain patterns, a soft deck brush worked in the grain direction helps without damaging the surface.
Professional Composite Deck Cleaning
D&D Home Services provides professional composite deck cleaning with the correct equipment settings and approved products. Contact us for a free estimate.
Key Takeaways
- ✓ Professional service saves time and delivers better results than DIY
- ✓ Regular maintenance protects your home's value and curb appeal
- ✓ D&D Home Services proudly serves Kitchener-Waterloo and surrounding areas
- ✓ Get a free no-obligation quote — call or book online anytime
Sources & References
- City of Kitchener — Property Maintenance Standards
- Ontario Building Code — Exterior Maintenance Guidelines
- D&D Home Services field experience across 500+ homes in KW Region
