How to Clean Composite Decking

Cleaning composite decking is a relatively simple task that requires a few basic tools and materials. The key to maintaining the deck’s appearance is consistent cleaning, which helps prevent dirt, stains, and algae from building up. By following the proper techniques, you can keep your deck looking new for years.

What Will You Need to Clean Composite Decking

To clean composite decking, you’ll need some essential tools and cleaning agents. A soft-bristled broom or brush is ideal for sweeping away dirt and debris. You’ll also need a garden hose or bucket for rinsing, a mild soap or deck cleaner, and possibly a pressure washer if you choose that method. Always have some clean water available to rinse the surface after cleaning.

Step by Step Guide for Cleaning Composite Decking

Begin by sweeping the deck thoroughly to remove any loose dirt, leaves, or debris. This will prevent dirt from being scrubbed into the surface. Next, prepare a cleaning solution using mild soap and warm water, or use a commercial deck cleaner. Apply the solution to the deck with a soft-bristled brush, working in sections. For stubborn stains, allow the solution to sit for a few minutes before scrubbing. Once you’ve cleaned the entire deck, rinse it thoroughly with water to remove any remaining soap or cleaner. Allow the deck to dry before using it.

Prepping, Ready for Cleaning

Before you begin cleaning, it’s important to prepare the deck. Start by clearing the area of any furniture or obstacles that may get in the way. If there is a lot of debris on the surface, consider sweeping or blowing it away first. This will ensure you can clean all areas of the deck thoroughly. For tougher stains, it may be helpful to pre-treat the affected areas with a stain remover or deck cleaner to give it time to work before scrubbing.

How Often Should It Be Cleaned?

The frequency of cleaning composite decking depends on its exposure to the elements. Generally, it’s recommended to clean your composite deck at least twice a year—once in the spring and once in the fall. However, if your deck is exposed to high foot traffic, heavy rain, or lots of debris, you may need to clean it more often. Regular cleaning helps prevent dirt, algae, and other stains from becoming ingrained in the material.

Can You Use a Power Wash on Composite Decking?

Yes, you can use a power washer on composite decking, but it must be done with caution. When using a power washer, always set it to a low-pressure setting to avoid damaging the surface of the deck. Hold the nozzle at least 8-12 inches away from the decking surface, and use a wide spray pattern to avoid focusing pressure on one spot. Too much pressure can cause the surface to scratch or become damaged over time.

Can I Clean Composite Decking with Washing Up Liquid?

Yes, you can clean composite decking with washing-up liquid, but it's important to dilute it with warm water. Avoid using an excessive amount of soap, as it can leave a residue that may be difficult to remove. Washing-up liquid is effective for light cleaning, but for tougher stains, a specialised deck cleaner might be more effective.

What Should You Not Use on Composite Decking?

It’s essential to avoid using harsh chemicals or abrasive cleaners on composite decking. Products like bleach, ammonia, and strong solvents can damage the surface and cause discoloration. Similarly, abrasive scrubbers or steel wool should not be used, as they can scratch and weaken the surface. Always stick to mild soap or deck cleaner for regular maintenance.

Can I Jet-Wash Composite Decking?

While you can use a jet washer, it's important to follow the manufacturer's guidelines carefully. As with power washing, ensure the pressure setting is low to prevent damaging the decking. Jet washing can be effective for removing dirt and debris, but excessive force can cause damage to the surface or the joints between boards. Always use a nozzle that provides a wide spray to avoid focusing pressure on one spot.

Is Vinegar a Good Composite Deck Cleaner?

Vinegar can be a good natural cleaner for composite decking, especially when combined with water. It works effectively on stains and can help remove algae and moss. To use vinegar, mix one part vinegar with three parts water and apply it to the stained areas. Let it sit for a few minutes before scrubbing the surface with a soft brush. Rinse the deck thoroughly after cleaning. However, be cautious when using vinegar in high concentrations, as it may damage the deck's surface if left too long.

Final Tips

Preventing Dirt Build-Up

To make cleaning easier and prevent dirt from accumulating on your composite deck, try to regularly sweep or rinse the surface. This is especially important during autumn when leaves and debris can accumulate more quickly. A quick sweep every few weeks will help prevent dirt from setting into the material, reducing the need for deep cleaning.

Cleaning Stubborn Stains

For tougher stains such as grease or oil, you may need to use a stronger cleaning solution. A mixture of water and a small amount of dish soap can help, but for more stubborn stains, consider using a composite deck cleaner that’s specifically formulated for removing tough stains without damaging the surface. Always follow the manufacturer's instructions when using specialised cleaners.

Use a Deck Sealer (Optional)

Some people choose to apply a composite deck sealer after cleaning to protect the surface from stains and dirt. While composite decking is already low-maintenance and resistant to mold and mildew, applying a sealer can help enhance its protection and longevity. If you choose to apply a sealer, make sure the deck is completely clean and dry before doing so.

Dealing with Mildew and Mold

In areas with high humidity, mildew and mold can sometimes grow on composite decking. If you notice any signs of mold, clean the area promptly using a mixture of water and vinegar, or a mild deck cleaner. For stubborn mildew, use a specialized cleaner designed for composite materials. Ensure the area is completely dry after cleaning to prevent future mold growth.

Be Cautious of Pressure Washers

While pressure washing can be effective for cleaning composite decking, it’s important not to use too much pressure. High pressure can damage the surface, leading to scratches or weakening the material. Always use a low-pressure setting and keep the nozzle at a safe distance (about 8-12 inches away). If you're unsure about the pressure settings, test a small area before cleaning the entire deck.

Seasonal Maintenance

It's a good idea to perform a more thorough cleaning at the start of each season—spring and fall. This will help you prepare the deck for heavy use during the warmer months and clean it after exposure to the elements. Seasonal cleaning also helps you spot any issues like loose boards or fasteners, which can be repaired before they become bigger problems.

Be Mindful of Pet Waste

If you have pets, clean up any waste promptly to prevent stains or odors. Composite decking is resistant to most stains, but pet waste can be more difficult to remove if left too long. Clean the affected area immediately using warm, soapy water to prevent discoloration and maintain the deck’s cleanliness.

Avoid Using Sharp Objects

When cleaning your deck, avoid using sharp or metal objects that could scratch or gouge the surface. Even though composite decking is more durable than wood, harsh scrubbing with metal brushes or using sharp tools can cause irreversible damage.