How to clean decking without damaging it

To clean decking safely, sweep it, apply a dedicated decking cleaner, scrub along the grain with a stiff brush, then rinse thoroughly. This removes the algae and grime that make decking slippery. A pressure washer can speed things up, but on timber it must be used at low pressure and kept moving, or it will raise the grain and cause splintering. Composite decking is easier but still needs regular cleaning to stay safe underfoot.

Why decking needs regular cleaning

Decking sits low, stays damp and is often shaded, so algae, mould and dirt build up quickly, especially over autumn and winter. The result is not just an unsightly green tinge but a genuinely slippery, hazardous surface. Cleaning once or twice a year keeps decking safe, extends its life and stops grime working into the grain.

Cleaning timber decking

• Clear the deck and sweep out the gaps between boards where debris collects.
• Wet the timber, then apply a decking cleaner suited to wood.
• Scrub along the grain with a stiff brush, working board by board.
• Rinse thoroughly and let it dry fully before replacing furniture.

If you use a pressure washer, keep it on a low setting, hold the nozzle well back, and move along the grain, never blast one spot, which gouges and splinters the wood.

Cleaning composite decking

Composite decking does not need oiling or sealing, but it still collects algae and grime in the surface texture. Warm soapy water and a soft brush handle most of it; a composite-safe cleaner tackles stubborn mould. Avoid wire brushes and high-pressure washing, which can scratch the surface. Rinse well so no soapy film is left to attract dirt.

Keeping decking non-slip

The slipperiness comes from algae, so the key is not letting it build up. Clean before autumn, keep gaps between boards clear so water drains, and trim back plants that keep the deck shaded and damp. Anti-slip decking strips are a good addition for steps and shaded areas. For surrounding paths and patios, the same principles apply, see our guide to removing moss from a patio.

Should you re-oil timber decking after cleaning?

Yes, cleaning strips away old oil and weathering, so timber decking benefits from re-oiling or re-staining once it is fully dry. This protects the wood, restores colour and helps repel water and algae. Composite decking does not need this.

When to call in the professionals

A small deck is manageable by hand, but a large or badly weathered deck, or one you want cleaned without risking the timber, is a job worth handing over. Our driveway and patio cleaning service includes decking, using the correct pressure and technique for the material so it comes up clean and safe without damage. For the best timing, see our guide to the best time of year to pressure wash.