How to Clean Composite Decking: The Ultimate Guide to a Sparkling Garden

You might have heard that “composite decking is maintenance-free!" While that is almost true (especially compared to timber, which seems to require a fresh coat of stain if you even look at it funny), it isn't quite the whole story.

Composite decking is very low-maintenance, but even the highest-quality boards need a little bit of love to keep them looking their best after a long British winter or a particularly enthusiastic summer BBQ.

Whether you’ve recently upgraded your garden with reliable Ecodek boards, or are weighing up whether the upgrade to composite vs timber is worth it (spoiler: it is), it’s good to know what you need to do to keep composite boards in tip-top condition. So, settle in: this guide will walk you through the simple steps to keep your deck looking brand new for decades.

Is composite decking low-maintenance?

The beauty of composite decking is that it doesn't rot, warp, or splinter. However, like any outdoor surface, it is subject to the elements. Dust, pollen, fallen leaves, and the occasional dropped burger can lead to a build-up of grime. If that’s left too long, this debris can trap moisture, which is exactly what leads to that slippery green algae we all want to avoid.

The good news? Cleaning composite decking is remarkably easy. You don't need expensive chemicals or back-breaking labour. Usually, you just need a bit of warm water and the right technique.

Choose the right composite decking for your lifestyle

When it comes to shopping for new decking and planning what your garden to-do list will look like, it helps to know exactly what kind of board you’re working with. Our Ecodek range offers two distinct ranges that cater to different needs and budgets:

The Ecodek Capped Range

The Ecodek Capped range is the super-shielded option with the most protection against the elements.

These boards feature a co-extruded outer layer (this is the "cap") that provides an extra level of protection against stains, scratches, and UV fading. Because the surface is non-porous, spills like red wine or grease tend to sit on top rather than soaking in, making them incredibly easy to wipe away. This is the ideal choice for dining areas or busy households with pets and kids.

The Cost-Effective Range

If you’re looking for the classic wood-look without the premium price tag, the Ecodek Cost-Effective range is a brilliant solution.

These composite deck boards are uncapped, offering a more traditional textured finish. While they are still vastly more durable than timber and need a whole lot less maintenance, they do require a slightly more thorough scrub if you spill something oily, as the surface is a bit more open than the capped version.

How to clean composite decking: step-by-step

For a general refresh just to get your garden space ready for the warm season, we recommend giving your deck a proper clean twice a year: once in the spring to clear off winter's grime, and once in autumn to remove fallen leaves.

1. Clear The Deck: Move your furniture and planters off the decking. This is a great time to check if any pots are leaving rings on the boards too, so you can restrategise.
2. Sweep Thoroughly: Use a stiff broom to remove loose leaves, dirt, and debris. Make sure to get into the gaps between the boards, as this is where moisture often gets trapped. Being able to do this without worrying about chipping off wood stain is one of the huge benefits of composite vs timber!
3. Use the Right Soap: Mix warm water with a mild, non-bleach dish soap or specialist composite cleaner. Avoid harsh chemicals, which can damage the finish of the boards and wear away the protective coating.
4. Scrub Gently: Use a soft-bristled brush to scrub the soapy water into the boards. Work with the direction of the grain to lift any stubborn dirt without disturbing the coating.
5. Rinse & Dry: Rinse the deck thoroughly with clean water (either use a bucket or a hose with a gentle spray). If you can, use a squeegee to remove excess water; this prevents water spots from forming as the deck dries. If you live in a hard-water area, you might notice a slight white film after rinsing. Adding a small amount of white vinegar to your rinse water can help neutralise the minerals and leave a streak-free finish across composite boards.

For more advice on maintenance, check out our blog on our top composite decking tips.

The best tools for cleaning composite decking

While composite decking maintenance is very straightforward, it’s a good idea to check you’ve got the right tools on hand before you start cleaning.

Avoid wire brushes or metal scrapers on your composite deck. While Ecodek is tough and designed to stand up to the elements, metal can scratch the surface of capped boards. Stick to nylon or natural bristles to remove any dirt or debris.

If you have stubborn debris stuck between boards (like small stones or twigs), you can use a plastic spatula or a blunt putty knife to gently clear them out without disrupting the frame or moving any boards too much. Remember, keeping the gaps between boards clear is vital for drainage and airflow.

How to get rid of stains on composite decking boards

Sometimes, a bucket of soapy water isn't quite enough. Here is how to handle the tougher stuff that’s a bit more stubborn.

1. Oil & Grease: If you drop food from the BBQ, it’s best to act fast. Blot the spill with a paper towel and wash with warm, soapy water immediately. For the Ecodek Cost-Effective range, you might need an alkaline-based cleaner if the oil has had time to sit.
2. Tannins (Brown Decking Spots): You might occasionally see small brown spots; these are usually tannins from organic debris like leaves. These usually fade naturally with sun exposure, but a quick scrub with soap will speed up the process and get your decking looking brand new again.
3. Algae & Mould: If your deck is in a permanently shaded area overlooked by trees or other plants, you might see a bit of a green tint after a while. A dedicated composite deck cleaner (non-bleach) is the best way to kill off the spores without harming your garden plants or damaging the cover layer on the boards.

Common mistakes when cleaning composite decks

1. Using a Strong Pressure Washer: We get asked this a lot: can I use a pressure washer on my decking? While you can use a pressure washer, you must be extremely careful.

   Use a low-pressure setting (under 1500 PSI) and keep the nozzle at least 30cm away from the surface. If the jet is too powerful, it can etch or scratch the boards, leaving permanent marks that can't be fixed. If in doubt, it’s always best to use a hose or a good ol’ bucket of water.

2. Using Bleach-based Cleaners: Never use chlorine bleach on composite decking. It can dull the colour of your boards and, in some cases, actually damage the structural integrity of the composite material. Over time, this will significantly reduce the overall lifetime of the deck.
3. Sanding Composite Decking: Unlike timber, you should never sand composite decking. This will remove the protective layer (especially on capped boards) and ruin the wood-grain effect.

Unlike timber, you should never sand composite decking. This will remove the protective layer (especially on capped boards) and ruin the wood-grain effect.

Ready to refresh your garden? Visit National Plastics

Whether you’re in the planning stages of a new garden renovation or looking for the right tools and accessories to maintain your existing space, National Plastics is here to help.

Our team can guide you through the differences between the Ecodek ranges and ensure you have everything you need for a professional-looking finish on your decking that lasts a lifetime.

Pop into one of our many local branches across the UK. You can see the Ecodek boards in person, feel the textures, and get expert advice on which range suits your garden's orientation.

For quick and easy ordering, browse our full decking range online. We offer 24/7 ordering with convenient delivery.

FAQs

Can I use a pressure washer on Ecodek decking?

Yes (in certain circumstances), but with caution. Ensure you use a fan tip, keep the pressure below 1500 PSI, and maintain a distance of at least 30cm from the boards. Incorrect use of a pressure washer is the most common cause of surface damage to composite decks. If you don’t absolutely have to, it’s best avoided.

How often should I clean my composite deck?

We recommend a thorough clean twice a year: once in the spring and once in the autumn. However, a quick sweep once a month to remove loose debris will make your bi-annual deep clean much easier.

Will my Ecodek deck stain if I spill wine or oil?

The Capped range is highly resistant to staining because the surface is non-porous. The Cost-Effective range is also very durable, but because it is uncapped, spills should be cleaned up as soon as possible to prevent them from soaking into the wood fibres.

Do I need to seal or varnish my composite decking after cleaning?

No! One of the biggest benefits of Ecodek composite decking is that it never needs sealing, staining, or varnishing. Once it's clean, you’re done: just sit back and enjoy your garden.