How to clean composite decking with a hose and brush

Get your composite decking ready for summer with our how-to guide

composite decking in outdoor space with tall green plants, a deck chair, festoon lights and candles
(Image credit: Lights4Fun)

Composite decking is a great low-maintenance option compared to traditional wooden decking. It’s available in a whole host of colours, widths, and effects, but while you can clean wooden decking with a pressure washer, composite decking can be damaged if you get too close with the jet.

So, what’s the best way to clean it? There are so many creative ways with garden decking, but composite decking ideas offer many more attractions over traditional timber decking. Its popularity began to grow in the late 1990s.

How to clean composite decking: a step-by-step guide

Today, you’ll find many brands offering a ten-15 year guarantee – boards shouldn’t warp, rot or splinter and a composite deck will also be anti-slip. ‘It’s also less likely to stain compared to traditional decking,’ says Allan Jeffrey, Commercial Director of Ultra Decking (opens in new tab).

‘It doesn’t need regular treating, staining, or painting either. Composite decking is manufactured from HDPE plastics and wood fibres to create hard-wearing decking boards.

composite decking in outdoor area with dog and seating area

(Image credit: B&Q)

The plastics used in the composite are often recycled, using waste materials like plastic bags and milk bottles,' says Allan. It’s less likely to splinter too, as it doesn’t absorb water in the same way, so it’s ideal for a space around a pool or hot tub.’

But composite decking doesn’t mean maintenance-free – if you look after your composite deck, then it will keep it looking its best for years to come. And while it’s less time-consuming to clean up at the beginning of the summer months, you still need to spend a little time and effort to get it looking as new.

Follow our easy step-by-step guide and spruce up your composite decking.

1. Get prepped for the project

First, remove garden furniture, pots, planters, doormats, and the barbecue. Then brush your composite deck with a soft-bristled brush to remove loose debris, such as grass cuttings, fallen leaves and twigs, trying to get in the gaps as much as possible.

If needed, use a scraper or putty knife to remove any dirt that’s trapped between the boards. You can also spray the area with a hose to remove debris.

composite decking in outdoor area with lots of green plants

(Image credit: Ultra Decking)

2. Clean any railings

If you have railings around your deck, then start by washing them down with soapy water and a decking cleaning hand brush, available at Amazon (opens in new tab). Then, hose it off, removing any debris and cobwebs. Deck railing ideas can really help create that sense of an outdoor room.

To clean the composite boards, mix up a bucket of warm soapy water and use a brush to get into the embossed pattern of your boards. You can also buy oxygenated cleaners, such as Oxylyse, but never use household bleach as you can discolour the boards, otherwise, normal washing-up liquid will do the job.

3. Wash the decking with soapy water

Working in a small section at a time – about 5-metre sections to prevent any cleaner from drying out and possibly leaving a film on the deck – wash the composite decking with the soapy water and the brush. Then rinse clean and allow to dry, before replacing your garden furniture and any pots moved.

If you have any stubborn planter or pot marks, then try giving more of a scrub, or using oxygenated cleaner and water to remove them.

4. Clean little and often

Rinsing off a composite deck periodically throughout the year will prevent the build-up of dirt, mildew, and grime. Spot stains – such as grease or spilt drinks – should be cleaned off affected boards with soapy water and left to ‘weather’ for a month or so to regain their original colour.

composite decking in outdoor with tall green plants and a deck chair and candles

(Image credit: Lights4Fun)

Can I jet-wash composite decking?

‘Many homeowners use a power washer to clean their decking because it’s faster, but when using one on composite decking, you need to be very careful. You should not apply too much pressure when using the machine,’ says Allan Jeffrey, Commercial Director of Ultra Decking.

‘Composite decking is not like a wood deck; while pressure washing your deck, the fan can damage its surface if you move the pressure washer too close to it. A water hose is a safe and good option if you want to rinse the surface of a composite deck.’

If you do decide to jet your composite deck, then use a fan tip nozzle and the washer’s lowest setting (no more than 1500psi). Spray in the direction of the board and keep the nozzle at least 20cm from the board.

Is vinegar a good composite deck cleaner?

‘Yes, it’s great for removing mould on composite decking,’ says Allan. ‘Mix a half cup of white vinegar with a gallon of water. Then use the mixture to scrub the decking.’

You can also use baking soda. ‘Sprinkle some on the decking then scrub with a soft bristle brush. Then rinse with clean water.’