How to Maintain and Clean Your Composite Decking in Cardiff

One of the biggest selling points of composite decking is how little effort it takes to keep it looking great. But low maintenance does not mean zero maintenance.

If you want your decking to stay in top condition for decades, especially in Cardiff’s unpredictable Welsh weather, a simple routine goes a long way.

In this guide, we’ll walk you through everything you need to know about maintaining and cleaning composite decking, from basic day-to-day care through to seasonal upkeep.

Whether you’re already enjoying a composite deck installed by Ellis Decks, or you’re thinking about upgrading your garden decking in Cardiff, this guide is here to help.

Why Composite Decking Is Low Maintenance (But Not No Maintenance)

Composite decking is engineered to resist the things that damage traditional timber: rot, warping, splintering and insect damage. That’s why so many Cardiff homeowners are making the switch.

But even the best composite boards will benefit from regular cleaning, especially here in South Wales, where damp conditions and leaf fall can encourage algae and mould growth over time.

The good news? Keeping on top of it is straightforward, and the time investment is minimal compared to sanding and staining a timber deck every year.

If you’re still weighing up your options, our guide on composite decking vs timber decking goes into more detail on the long-term differences in maintenance.

Routine Composite Decking Cleaning: What to Do and How Often

Weekly or Fortnightly (During High-Use Periods)

During spring and summer when your deck gets the most use, a quick sweep is all you need. Remove loose leaves, dirt and debris before they have a chance to break down and stain the surface.

What you’ll need:

• A stiff-bristled brush or broom
• A garden hose

What to do:

• Sweep the deck thoroughly, paying attention to the gaps between boards where debris collects
• Rinse down with a hose if needed
• Allow to air dry

That’s it. Ten minutes is usually enough to keep your deck looking fresh.

Monthly Wash

Once a month, or after any particularly wet or muddy period, give the deck a proper wash down.

What you’ll need:

• Warm soapy water (washing up liquid works well)
• A soft to medium-bristled deck brush
• A garden hose

What to do:

• Wet the surface with your hose
• Apply your soapy water and scrub in the direction of the board grain
• Rinse thoroughly and leave to dry

Avoid scrubbing against the grain as this can dull the surface over time. Always rinse well so no soap residue is left behind. Trex also has its own care and cleaning guide.

Dealing with Stubborn Stains on Composite Decking

Cardiff’s gardens are put to work: BBQs, children, pets, outdoor dining. Stains happen. Here’s how to deal with the most common ones.

Food and Grease Stains

Act fast. The sooner you tackle a food or grease stain, the easier it comes off.

• Use warm soapy water and a cloth or brush
• For stubborn grease, a dedicated composite decking cleaner works well
• Avoid leaving cooking oils or fat to sit on the surface after BBQs

Bird Droppings

Bird mess is acidic and can cause surface marks if left for a long time.

• Remove solids first with a plastic scraper, never metal
• Follow up with warm soapy water and a brush
• Rinse thoroughly

Mould and Algae

Cardiff’s wet climate makes algae and mould growth a real consideration, particularly in shaded areas or during autumn and winter.

• Use a purpose-made composite decking cleaner or a diluted white vinegar solution
• Scrub in the direction of the board grain with a stiff brush
• Rinse thoroughly
• Consider a composite decking treatment solution if the problem persists

Never use bleach-based cleaners or products not designed for composite decking, as these can discolour or damage the surface. Our guide to composite decking problems in South Wales explains why algae builds up in the first place.

Leaf Stains and Tannin Marks

Wet leaves left sitting on composite decking can leave tannin stains, particularly in autumn.

• Regular sweeping during autumn is your best prevention
• For existing marks, a composite deck cleaner and a scrub brush should lift them
• Rinse well afterwards

Can You Pressure Wash Composite Decking?

This is one of the most common questions we get asked. The short answer is yes, but carefully.

Most composite decking, including Trex composite decking, can be cleaned with a pressure washer on a low setting. The key rules are:

• Use a fan or wide-angle nozzle, not a jet nozzle
• Keep the pressure below 1,400 PSI (lower is better)
• Keep the nozzle at least 20 to 30cm from the surface
• Always spray in the direction of the board grain
• Never hold the nozzle in one spot

High-pressure concentrated jets can permanently damage the surface texture of composite boards, so if in doubt, stick to a regular hose and brush.

Need a hand with an existing deck, or planning a new one? Call Ellis on 07971 750900 or request a free estimate.

Seasonal Composite Decking Maintenance for Cardiff Homeowners

Spring

Spring is the best time to give your deck a thorough clean after winter. Cardiff winters can be damp and mild, which creates ideal conditions for mould and algae.

• Full sweep and wash down
• Check board fixings and frame for any movement
• Inspect for any algae or mould build-up and treat if needed
• Clear out any debris from between boards
• Check drainage around the deck is clear

Summer

Summer maintenance is minimal. Keep on top of sweeping and clean up spills quickly, particularly during BBQ season.

• Regular sweeping
• Wipe up food and drink spills quickly
• Rinse down after parties or outdoor dining
• Check furniture legs aren’t trapping moisture or debris against the boards

Autumn

Autumn is when Cardiff gardens fill with fallen leaves, and this is when composite decking needs the most attention.

• Sweep leaves regularly, and don’t let them sit and decompose on the surface
• Clear debris from between boards
• Full wash before winter sets in
• Check drainage channels are clear before the wet season

Winter

Composite decking handles Cardiff winters well. Unlike timber, it won’t rot, warp or splinter in damp conditions. That said, a little care goes a long way.

• Keep the surface clear of debris
• Remove standing water where possible
• In icy conditions, use a plastic shovel to remove snow, never metal
• Use sand or cat litter for grip in icy weather and avoid de-icing salts, as these can damage the surface over time

What to Avoid When Cleaning Composite Decking

Getting the cleaning right is just as much about what you don’t do. Here’s a quick list of things to avoid:

• Bleach or chlorine-based cleaners, as these can strip colour and damage the surface
• Metal scrapers or wire brushes, as these will scratch and gouge composite boards
• Scrubbing against the grain (always work in the direction of the board instead)
• Leaving wet leaves or debris to sit, particularly during autumn and winter
• High-pressure concentrated jets (use a wide fan setting if using a pressure washer)
• Furniture without protective feet (use rubber or felt pads under garden furniture to avoid scratching)

How Long Does Composite Decking Last With Proper Maintenance?

With regular cleaning and basic upkeep, quality composite decking is built to last for decades. Trex backs its decking with fade and stain warranties of 25 or 50 years depending on the range, a level of confidence you simply don’t get with timber. Read more in how long composite decking lasts in the UK.

The lifespan of your decking comes down to two things: the quality of the product and the quality of the installation. That’s why choosing an experienced, specialist installer matters.

As a TrexPro® Gold installer, Ellis Decks installs composite decking to the highest standards, ensuring your deck is built to last from the ground up.

Ready to Transform Your Cardiff Garden?

If you’re thinking about composite decking for your Cardiff home, or you’d like advice on looking after an existing deck, Ellis Decks are here to help.

We install premium composite decking across Cardiff and South Wales, combining expert craftsmanship with industry-leading products. As a TrexPro Gold installer, we bring a level of expertise and accountability that sets us apart.

Call 07971 750900 or get in touch with Ellis Decks today for a free, no-obligation quote and expert advice tailored to your garden and your budget.

Ellis Decks LTD install composite and timber decking across Cardiff and South Wales. Find out more about the areas we cover.