The Best Practices for Cleaning Composite Decking with a Pressure Washer - Pressure Washer
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The Best Practices for Cleaning Composite Decking with a Pressure Washer

The Best Practices for Cleaning Composite Decking with a Pressure Washer

Composite decking, with its blend of wood fibers and plastic components, offers a durable and low-maintenance alternative to traditional wood decking. However, exposure to the elements can leave it dirty, stained, and in need of a thorough cleaning. Using a pressure washer is an effective way to clean composite decking, but it requires specific techniques to avoid damage.

This article outlines the best practices for safely and efficiently cleaning composite decking with a pressure washer.

1. Preparation

Before you start, remove all furniture, grills, and decorations from the deck. Sweep the surface to remove loose dirt, leaves, and debris. This step ensures that the pressure washing is as effective as possible and prevents debris from becoming flying projectiles under high pressure.

2. Choose the Right Pressure Washer

Not all pressure washers are suitable for cleaning composite decking. A pressure washer with adjustable pressure settings is ideal, as composite decking can be damaged by too much pressure. Opt for a unit that allows you to work within a range of 1300 to 1600 pounds per square inch (PSI). This range is generally safe for composite materials, effectively cleaning the surface without causing damage.

3. Select an Appropriate Nozzle

The choice of nozzle is crucial for the safety of your decking. A wide-angle nozzle (typically 40 degrees) is recommended because it disperses pressure over a broader area, reducing the risk of damaging the composite material. Avoid using a zero-degree nozzle, as its concentrated stream is too powerful and can easily erode or cut into the decking.

4. Use a Fan Attachment (If Available)

If your pressure washer comes with a fan attachment, use it. The fan attachment further spreads out the water pressure, making it even less likely to damage the decking while still providing adequate cleaning power.

5. Test in an Inconspicuous Area

Before you begin the full cleaning, test the pressure washer on a small, inconspicuous area of your decking. This step allows you to adjust the pressure settings and nozzle choice as needed, ensuring you won’t damage the entire decking area.

6. Apply a Deck Cleaner (Optional)

For decks with heavy staining or mildew, consider applying a composite deck cleaner before pressure washing. Follow the manufacturer’s instructions for application. These cleaners are formulated to tackle tough stains and can help ensure a more thorough cleaning. Allow the cleaner to sit on the deck for the time recommended by the manufacturer, but do not let it dry completely.

7. Maintain a Safe Distance

When using the pressure washer, maintain a consistent distance of about 8 to 12 inches from the decking surface. This distance is optimal for cleaning effectively without concentrating too much pressure on any single point, which could damage the composite material.

8. Use a Sweeping Motion

Move the pressure washer nozzle in a sweeping motion across the decking boards, keeping the stream at a consistent angle and distance from the surface. Work in sections, systematically moving across the deck to ensure even cleaning. Overlapping each pass slightly will help prevent streaks.

9. Rinse Thoroughly

After cleaning the deck with the pressure washer (and cleaner, if used), make sure to rinse the surface thoroughly with water. This step removes any residual cleaner and debris, leaving your composite decking looking as good as new.

10. Allow to Dry Completely

Before replacing furniture and decorations, allow the decking to dry completely. This prevents trapping moisture, which could lead to mold or mildew growth, undermining your cleaning efforts.

11. Regular Maintenance

While pressure washing is an effective cleaning method, regular maintenance can reduce the need for it. Sweep the deck regularly to remove debris and clean spills promptly to prevent staining. This proactive approach will help keep your composite decking looking great year-round.


Cleaning composite decking with a pressure washer is an effective way to restore its appearance, but it requires careful attention to technique and settings to avoid damage. By following these best practices, homeowners can ensure their decking remains clean and in good condition, extending its lifespan and enhancing outdoor living spaces.

Remember, the key to successful pressure washing is to use the right equipment, maintain a proper distance, and employ a gentle sweeping motion to achieve a thorough, damage-free clean.