How to clean decking in this DIY step-by-step guide

Wooden decking being sprayed with deck cleaner showing the before and after
(Image credit: V33)

Knowing how to clean decking is essential if you want it to stay looking good and last longer. When the warmer evenings are just around the corner you want to get your decking back up to scratch. No-one wants to sit out on a deck that is slimy, grimy and slippery when sipping a long cool drink or enjoying outdoor dining.

But the joy of freshly reinvigorated decking is that it’s not just easy on the eye, it's easy on your pocket. Keeping a deck clean means that all the hard work you put into your garden decking ideas will ensure that they stay looking good for longer. Here the pros tell you what you need to know.

Before you start to clean your decking

Take everything off your decking so it’s completely clear and ready for you to clean.

Grab a broom and give your decking a good sweep to dislodge any dirt – don't worry too much about any particularly problematic dirt, as that can be tackled with a deep clean of your decking.

Image fencing expert Leigh Barnes of Jackson Fencing
Leigh Barnes

Leigh has 20+ years of experience in the timber/ construction industry. Since joining Jacksons Fencing in 2019, he has been instrumental in leading the retail team, focusing on driving the timber division side of the business.

The tools you'll need to clean decking

You need to gather a few tools to get the job done. These include:

How to give timber decking a light clean

light decking and fencing in a garden

(Image credit: Ronseal)

1. First clean

Make sure that you have swept your decking. Then give your timber decking a gentle clean, first using slightly soapy water and a sponge to remove dirt and cobwebs.

2. Remove stubborn dirt

For more stubborn dirt, try a very light abrasive such as a nylon kitchen scourer, used along the grain. "Do not rub against the grain," says Jacksons Fencing's Leigh Barnes, "as it is likely to leave marks."

3. Use a pressure washer

You can use a pressure washer, but care must be taken as not to damage the surface of the timber. Use a very light/distant cold water pressure washer for the job. Remember to find the best pressure washer for the job at hand — rotary pencil jet nozzles aren't suitable for timber surfaces.

How to deep clean timber decking

“The first job is to ensure decking is properly clean before - ideally - applying decking oil to ensure it will be water-repellent and UV-protected.” says Richard Bradley, UK Head of Marketing at V33.

“Seek out a deck cleaning fluid that is specifically formulated for this job so that you can revive the decking’s wood without altering it.” He adds, “What you are looking for is a fluid that effectively cleans, removes mould, mildew and black spotting, and eliminates greying. Ideally, a concentrated formula will provide high coverage that can easily tackle heavily soiled areas, even stubborn stains."

V33 Tough Deck Clean & Revive (available from B&Q) can be applied on either bare or oiled decking. Here Bradley runs through how to use the deck cleaner. “Firstly, brush the wood to remove excess dirt. Dilute the cleaner in a proportion of one unit of cleaner to two units of warm water.”

He adds, “This solution can then be applied in two ways. If using a pressure washer, spray the decking and then leave it for ten minutes before rinsing with clean water.” If using a brush Bradley says, “Pour the solution onto the surface using a watering can, leave for ten minutes, rinse, and then scrub using a hard-bristle or patio brush, followed by more rinsing.”

Richard Bradley, UK Head of Marketing for V33
Richard Bradley

Richard Bradley has over 16 years of specialist marketing experience in the coatings industry, working with leading paint brands. V33’s Renovation range of paints and decking care products is sold through B&Q, Screwfix and Amazon.

How to clean composite decking

The material finish of composite decking means that it does not require painting, staining or oiling. This means that cleaning process is different to a traditional timber decking.

how to clean decking tutorial

(Image credit: Neotimber)

The tools you'll need to clean composite decking

Tool list

  • A soft bristled brush (anything other may be abrasive to the surface of the deck)
  • A hose pipe (like this Expandable Garden Hose from Amazon)
  • A regular sponge
  • A bucket of warm water
  • Domestic soap
  • Pressure washer
  • Composite decking cleaner 

How to give composite decking a quick clean

1. Brush the deck with warm water

Mix a bucket of warm water with household soap (washing-up liquid will do the trick). Apply this directly onto the deck and clean thoroughly with a soft bristled brush.

"Brush the surface of the deck along the length of the grain of the board to ensure dirt and debris is being removed from the expansion gaps between the boards," suggest the experts at Neotimber.

How to Clean Decking tutorial

(Image credit: Neo Timber)

2. Clean trim and edges

The edges of your deck, especially where trims are installed, can often collect dirt and debris, so take extra care with these areas by applying warm soapy water to the surface of the deck and clean with a sponge.

How to clean decking tutorial

(Image credit: Neotimber)

How to deep clean composite decking

1. Treat with deck cleaner

Once the area has been cleared of all furniture and excess debris, you are ready to treat your deck a treatment. Firstly, apply a thick layer of composite decking cleaner such as Owatrol Compo-Clean to the surface of your composite deck.

Large areas should be cleaned in smaller sections. Follow the manufacturer's instruction for the composite decking cleaner you choose.

2. Jet wash boards

Using a jet wash (check the best Karcher pressure washers) on the fan attachment, rinse your deck. Apply the nozzle of the jet wash no closer than 250mm from the surface of the deck boards — any closer and you risk damaging the surface of the decking.

Clean along the length of the deck boards and pay extra attention to debris that is lodged between the board’s expansion gaps.

how to clean decking tutorial

(Image credit: Neotimber)

3. Tackle hard to reach spots

Pay attention to hard to reach spots and tackle these areas with some additional care. Either remove the surface dirt with a sponge or devote a little more attention to these areas with your jet wash.


Cleaning decking is all part of the decking maintenance process. how long decking lasts depends on how it is looked after and what material is made from. If you're looking to build or repair a wooden deck make sure to check out our best wood for decking guide.

Hugh is editor of sister title Livingetc.com and former digital editor of homebuilding.co.uk. He has worked on a range of home, design and property magazines, including Grand Designs, Essential Kitchens, Bathrooms, Bedrooms and Good Homes. Hugh has developed a passion for modern architecture and green homes, and moonlights as an interior designer, having designed and managed projects ranging from single rooms to whole house renovations and large extensions. He's currently renovating his own Victorian terrace in Essex, DIYing as much of the work as possible. He's recently finished his kitchen renovation, which involved knocking through walls, and landscaping a courtyard garden, and is currently working on a bathroom renovation.

With contributions from