Composite decking has become a popular choice for homeowners looking for low-maintenance, durable outdoor living spaces. But even though it’s more resistant to weather and rot than traditional wood, it’s not immune to dirt, grime, mildew — or bad cleaning techniques. One question that comes up often is: Can you power wash composite decking without damaging it?
The short answer is: Yes, but only if you do it correctly. Let’s break down everything you need to know to keep your composite deck clean — and safe. 🧼🧠
🌳 What Is Composite Decking?
Composite decking is made from a mix of wood fibers, plastic, and bonding agents. It’s designed to look like wood but without the constant need for staining, sealing, or replacing rotted boards. Popular brands include Trex, TimberTech, and Fiberon.
Benefits of composite decking:
- Resistant to rot and insects 🐛❌
- Doesn’t splinter like wood
- Holds up well in rain, sun, and snow
- Generally low-maintenance
But “low-maintenance” doesn’t mean no maintenance — and that’s where power washing comes in.
🚿 Is Power Washing Safe for Composite Decking?
Yes, but only if you follow the proper guidelines. Composite boards are softer than concrete or hardwoods. Using too much pressure, holding the nozzle too close, or using the wrong attachment can gouge, scratch, or warp the boards.
✅ Power Washing Can:
- Remove surface dirt and grime
- Clear out algae and mildew
- Prep the deck before sealing (if needed)
❌ Power Washing Can Also:
- Leave visible etching or damage
- Void some manufacturer warranties
- Push water into seams and create swelling
🔧 Manufacturer Recommendations
Let’s look at what some of the biggest composite decking manufacturers say:
- Trex: Use a pressure washer with a fan tip and a pressure of no more than 3100 PSI. Keep the nozzle 8 inches or more from the surface.
- TimberTech: Recommends 1500 PSI max and a wide fan tip.
- Fiberon: Advises using a fan tip nozzle with low pressure and not getting too close.
💡 Pro Tip: Always read the care and cleaning guidelines for your specific brand of decking before using a pressure washer.
🧼 Step-by-Step: How to Power Wash Composite Decking Safely
1. Sweep the Deck First
Remove all debris, leaves, and dirt. Use a broom or leaf blower to clear the surface so your washer isn’t pushing grit around and scratching the boards.
2. Choose the Right Pressure Washer Settings
- PSI: 1500–2000 is usually safe
- Nozzle: Use a 25° or 40° fan tip
- Distance: Hold the wand at least 8–12 inches away from the surface
Never use a zero-degree (pencil) nozzle — that kind of pressure can cause permanent damage. ❌
3. Use a Composite Deck Cleaner
Most composite decks benefit from using a manufacturer-approved cleaner. These are specially formulated to break down mildew, algae, and grime without harming the plastic or resin in the material.
🧪 You can also make a homemade solution:
- 1 gallon warm water
- 1 cup vinegar or mild dish soap
- (Avoid bleach unless it’s heavily diluted and plant-safe)
4. Apply Cleaner and Let It Sit
Spray or brush on the cleaner and allow it to dwell for 5–10 minutes. This gives it time to break down any organic buildup like moss or mildew. Don’t let it dry on the surface.
5. Power Wash in a Consistent Pattern
Move in long, smooth, side-to-side motions. Always follow the grain of the deck boards. Keep your arm steady and don’t linger in one spot — this prevents streaking and gouging.
6. Rinse Thoroughly
Make sure all detergent is removed. Leftover residue can attract dirt or leave white streaks when dry. A garden hose rinse afterward can help make sure everything is clean and neutralized.
7. Let It Dry Completely
Allow the deck to dry for 24–48 hours. Don’t place furniture or walk on it heavily until it’s fully dry. 🌤️
⚠️ What NOT to Do
- ❌ Don’t use a zero-degree tip (way too strong)
- ❌ Don’t exceed 3100 PSI
- ❌ Don’t get closer than 8 inches to the surface
- ❌ Don’t use harsh chemicals like acetone or full-strength bleach
- ❌ Don’t wash against the grain or spray upward into board seams
🧠 Alternatives to Power Washing
If you’re not comfortable using a power washer — or your composite brand advises against it — try:
- Soft washing: Uses low pressure and cleaning agents
- Scrubbing: With a soft brush and approved composite cleaner
- Deck cleaner with hose attachment: A milder option for basic upkeep
These are great for regular maintenance without the risk of pressure-related damage.
🏁 Final Thoughts
So, can you power wash composite decking without damaging it? Absolutely — but only if you treat it with care. Stick to low pressure, a wide nozzle, and plenty of space between the wand and your deck.
Composite decks are built to last — don’t cut that life short by blasting them with high pressure. Clean regularly, be gentle, and your deck will stay beautiful for years to come. 🛠️🧼🌟
