How to Clean Composite Decking

Decking can completely transform your garden, bringing modern class to any space. However, keeping it clean can be a bit of a chore as it’s so easy for dirt and algae to build up on its surface. Thankfully, this task is much easier with composite decking compared to traditional timber decking boards. There are many ways to clean composite decking, whether using a pressure washer or something as simple as a bucket of soapy water and a brush. Keep reading to find out how to clean and maintain your composite decking.

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When everyday cleaning composite decking, remove any furniture, rinse the surface, and scrub it with warm soapy water. For deeper cleans, you may require a pressure washer or a mould remover to tackle tough stains and algae build-up.
Composite decking is low-maintenance and more durable than timber, with capped versions offering extra protection against weathering and wear. It mimics the look of wood without being prone to warping, splintering, or cracking.
Decking should be cleaned twice a year and applying damage prevention is key for stubborn stains. For everyday spills, spot-clean them quickly to maintain your deck’s appearance and longevity.

What is composite decking?

Composite decking is a type of decking that’s made up of a combination of plastic and wood fibres. This creates a surface that’s much easier to maintain compared to timber decking, which requires extra steps like wood treatments.

Composite decking is particularly popular for outdoor living spaces that experience a lot of footfall because of its durability, as it won’t warp, splinter, or crack as easily as wooden boards. However, it mimics the aesthetic of traditional timber decking to achieve a sophisticated look without having to rely on natural materials that are more susceptible to wear and tear.

The difference between capped and uncapped composite decking

The two main types of composite decking are capped and uncapped boards. Capped decking is covered by a protective layer that makes it more durable and often has more detail and texture. On the other hand, uncapped decking is generally cheaper but more susceptible to the elements as it lacks this extra protective layer. Regardless of whether you choose capped or uncapped, it’ll still require less maintenance than wood.

A step-by-step guide to cleaning composite deck boards

Follow our simple steps to refreshing your composite decking, expanding its lifespan and keeping it looking presentable.

Before you clean a composite deck, remove any furniture, ornaments, and plants from your deck so you’ve got a blank canvas. Take care not to drag furniture while removing it as this can scratch your decking. You’ll also want to clear any leaves or dirt from the surface using either a soft bristled broom, dustpan and brush, or a vacuum cleaner.

To make the cleaning process easier and to loosen any stubborn dirt, you’ll need to soak your deck. You can do this with a hose or a bucket of warm water.

Composite decking doesn’t require a specialist deck cleaner. All you need to do is mix up a solution of warm water and mild soap, and scrub this into the deck with a soft-bristled brush. Make sure to work in the direction of the slats so the brush gets all the dirt in between each board. You’ll also want to work in small sections to make sure your deck is getting even coverage.

For more hard-to-reach areas like corners, nooks, and trims, soak a sponge in warm soapy water and scrub it into the boards.

When it comes to how to remove mould and mildew from composite decking, apply a specially formulated mould and algae remover to the area and let it soak before rinsing it off with a hose or pressure washer.

If your composite decking has been subjected to a lot of dirt and stains over the summer or winter, you may want to carry out a deep clean. The best way to do this is with a pressure washer. To avoid causing damage to the deck, use a setting no higher than 1200 psi, and make sure to clip on the fan attachment prior to starting. You’ll also want to keep a distance of at least 250mm from the surface to avoid any damage. Again, work with the grain of the decking as you spray.

Once your composite decking has completely dried, you can return all your furniture and plants.

And there you have it, a spick and span deck. We recommend you keep on top of its cleanliness throughout the year so that your decking is always looking its best and is ready to be used at all times.

Accidents happen, but this doesn’t mean you need to clean the entire deck after just one spill. For grease and oil stains, we recommend quickly using a dedicated grease and oil remover and scrubbing it into any spots that may have been affected. For stains caused by food or other spills, use a spot-clean with a stain remover.

Generally, you’ll only need to clean your composite decking twice a year, and the best times to do this is during spring and autumn. Cleaning it in spring prepares it for heavier use in the summer and cleaning it in autumn prepares it for the winter ahead.

How to prevent damage to decking

Prevention is key to keeping your decking looking its best. Protecting your decking from damage will save you time, money and energy, especially if you’ve got uncapped decking which doesn’t have a protective layer. To avoid scratches, use furniture pads or mats underneath any décor, plants and furniture to protect the surface. You’ll also want to minimise moisture to your composite decking, so introducing shade from the rain through a parasol can help to prevent staining, as well as algae or fungal growth.

The easiest and most effective way to protect your deck from staining is to seal it with a quality and UV-resistant composite deck sealer, and always clean spills immediately after they’ve happened if possible.

Maintaining the colour of composite decking after cleaning

To ensure your composite deck maintains its wood-like colouring, we recommend doing the following:

Apply a composite deck sealer which locks in colour and protects it against UV rays

Clean the surface regularly

Avoid harsh chemicals or pressure washing too close as this can cause dulling

Use outdoor rugs

Minimise direct sunlight exposure

Long-term effects of improper composite decking cleaning

If you’re not cleaning your composite decking properly or infrequently, you may cause stubborn stains to form, mould growth, and even surface discolouration that would be difficult to reverse. As a general rule, never use harsh chemicals or abrasive tools to clean your composite deck, as this will likely scratch and strip the surface, making the boards more prone to moisture and UV damage. This not only dampens the look of your decking but can shorten its lifespan.

If your decking saw a lot of use in the summer months, or the unrelenting winter weather took its toll, it’s likely built up some dirt as a result. If this is the case, you don’t need a pressure washer to clean your composite decking – just use the old reliable ‘soapy water and a brush’ method. For more information about how to care for your decking, visit our comprehensive decking hub.

FAQs

We wouldn’t recommend using bleach on composite decking as a corrosive substance like this can cause it to chip and discolour much faster. Even diluted bleach can cause damage to composite decking, so please steer clear of this too. Warm soapy water is ideal for a standard clean, and then introduce specialist cleaning products when undergoing a deeper clean.

Firstly, always wear gloves before dealing with bird poop. Then get rid of the main bulk of the mess with a broom, hose, or pressure washer. You shouldn’t need anything more than a mild detergent, a soft brush, and a bit of elbow grease to remove what’s left of the bird poop.