Uncapped Composite (First Generation)

Uncapped boards feature an exposed wood-fibre surface texture. Because the wood fibres are exposed, the board is slightly porous.

• The Reality: If not cleaned regularly, the boards will hold onto surface moisture, leading to the build-up of algae and unsightly watermarks. Damp leaves left on the deck in autumn will break down and cause organic tannin stains.
• The Routine: We advise a quick wash once a month, especially heavily in Spring and Autumn.

Capped Composite (Second Generation)

Capped boards have a thin, highly advanced protective plastic shield (the “cap”) wrapped completely around the core.

• The Reality: This shield drastically reduces moisture absorption, starving mould and mildew of the damp environment they need to grow. The cap is also highly resistant to common household spills (like red wine) and grease from family BBQs, which would normally permanently stain an uncapped board.
• The Routine: A quick wash quarterly (every 3 months) is usually more than enough.

What You Will Need:

• A bucket of warm water.
• Standard household washing-up liquid (dish soap).
• A soft-bristle sweeping brush (Crucial: avoid stiff/hard bristles to prevent scratching).
• A standard garden hose (or a power washer on a strictly low 1500 psi setting with a wide fan nozzle).

The Method:

1. Clear & Sweep: Remove all garden furniture and plant pots to expose hidden dirt traps. Sweep away all loose dirt and leaves while the deck is dry. It is vital to use your brush to clear the expansion gaps between the boards so rainwater can drain freely. If your gaps are too tight and water is constantly pooling, review our ultimate guide to installing composite decking to understand how your spacing should be structured.
2. The Wash: Apply the warm soapy water to the deck and scrub gently with your soft brush, working in the direction of the wood grain.
3. The Rinse: Rinse the decking down thoroughly with a garden hose to ensure no soapy residue is left behind to dry.

The DIY Solution: White Vinegar & Baking Soda

This is a cheap, safe household trick that works wonders on isolated mould spots or stubborn grease.

• The Method: Pour standard white household vinegar directly onto the target area and sprinkle a little baking soda over it. Scrub immediately while it is actively fizzing, then flush heavily with clean water.

The Tradesman Tip: You might read online guides telling you to let the mixture sit for a few minutes. In our experience, this is a mistake. The actual cleaning power comes from the chemical reaction (the fizzing) physically lifting the grime out of the board’s grooves. If you wait a few minutes, the reaction finishes, the fizzing stops, and you are just left with a puddle of salty water that does nothing. Scrub while it fizzes!

Dedicated Cleaners (Owatrol Compo-Clean)

If the DIY methods fail, use a dedicated, professional-grade composite cleaner like Owatrol Compo-Clean. It is specifically formulated to lift heavy grime and oils without damaging the plastic cap or stripping the colour.

Restoring Faded Colour (Owatrol Compo-Care)

Has your older deck faded over the years? You can use a dedicated “Reviver” like Compo-Care.

• How it works: Unlike a cleaner, this product actually revives the colour pigments and adds a fresh layer of protection against the elements, restoring the original look of tired boards.

⚠️ Important Tradesman Note: Revivers are primarily designed for Uncapped (First Gen) composite, which is porous enough to absorb the liquid. Do not apply stains or revivers to Capped decking without checking with the manufacturer first. The non-porous cap will prevent the product from drying, leaving your deck permanently sticky!

Part 4: What To AVOID (The Danger List)

Composite is incredibly resilient, but certain products and habits will ruin it.

• Unprotected Furniture Legs: Dragging metal chairs or heavy tables is the fastest way to gouge your deck. Always apply rubber feet or protective felt pads to the bottom of your garden furniture.
• Bleach: Never use bleach. It is far too harsh and will chemically degrade the plastic fibres, permanently leaching the colour pigments and leaving ruined white patches.
• Magic Erasers: A Magic Eraser is essentially extremely fine sandpaper. Scrubbing too hard with one will permanently strip the texture and colour from the board. Avoid them entirely.
• Metal Tools: Metal snow shovels or wire brushes will gouge the deck. Once a capped board is deeply scratched, the protective seal is broken.

Part 5: Winter Care Protocol

Winter is the toughest time for any garden boundary or patio.

• The Pre-Winter Clean: Remove all wet leaves before the first frost hits. If you leave organic matter trapped under the snow, it will rot and cause stubborn tannin stains by Spring.
• Snow Removal: Never use a metal shovel. Always use a plastic or rubber-edged shovel to push snow off the deck, running parallel to the boards.
• Ice Control (The Pro Tip): Be incredibly careful with standard Rock Salt. As the ice melts and evaporates, rock salt leaves heavy white residue marks, and the abrasive crystals can scratch the boards underfoot. Instead, we highly recommend using Calcium Chloride (white ice melt). It is gentler on composite, leaves less residue, and melts ice at much lower temperatures (-32°C) than standard rock salt.