How to clean decking

Want the lowdown on how to clean decking? Follow these top tips and get it looking its best for summer

How to clean decking
(Image credit: sadolin)

Looking for quick tips on how to clean decking? While a thorough vacuuming or even a quick steam is enough to clean up your flooring indoors, your deck might want a rather more robust approach to tackle any moss, mould and algae that’s grown on it and made it dangerously slippy underfoot.

As staying in has become the new going out, having a decked terrace has been as good as an extra room, so it pays to keep it looking pristine during the summer months. Follow our advice and you’ll soon have it looking its best and clean enough to walk on barefoot. 

Looking for more advice on garden decking? You’ll find them in our decking buying guide

What you'll need

How to clean decking

First clear the decks, literally. Move away any plant pots and outdoor furniture that have spent the winter there gathering debris round their bases. Sweep your deck using a long handled deck brush, and clear out the cracks of all of nature’s detritus that might have blown or dropped into it.

The quickest way to clean the wood is using a deck cleaner, making sure you use protective gloves for this. Follow the manufacturers instruction’s regarding application, leave it to work if there is a time specified, then rinse with clean water. Alternatively, try a spray and walk away cleaner. It goes to work on moss and algae overnight and dries off naturally.

If you want a less strenuous method, try a no-scrub spray and walk away cleaner. The most effort required is in diluting it with water and mixing it up. Either spray on or sprinkle on with a watering can, then walk away and leave it to work on the mildew and algae for a few days.

Clean decking with soapy water

It's also possible to clean decking with a basic soap solution. Simply use a mix of washing-up liquid in warm water or go for half bleach and half warm water – both mixtures should be enough to deal with algae and mildew. Give the boards a thorough scrub with the cleaning solution, using a special scrubbing brush such as the Tough Deck Scrubber Brush, then rinse down with water.

Use soda crystals to clean decking

To make a homemade decking cleaner, create a paste by stirring two to three tablespoons of laundry starch into 500ml of lukewarm water. Keep stirring until all the lumps have gone. Pour this starch mixture into a large pan containing five litres of lukewarm water, then add 100g of soda crystals (sodium carbonate) and boil until the liquid starts to thicken. 

Apply it to the wooden boards of your deck and spread it evenly with a brush, then leave the paste to work for a few hours. Rinse the home-made cleaning paste off the decking with water.

How to clean decking with a pressure washer 

If you have a pressure washer or hose, you can force the dirt away. Don’t direct the jet of water straight at the decking as the pressure could wash away wood adhesive and make material become brittle. 

Keep the pressure on the lowest setting, stand at a distance so the spray isn’t too close to the deck then spray it section by section. Wash it as evenly as possible. You could even get a wash brush attachment for a pressure washer to help do the job.

If you plan to stain or treat the deck after, make sure you let it dry thoroughly before applying any decking stain so it doesn’t trap moisture as this could rot the wood.

Other points to consider 

Stihl, the makers of garden and power tools, recommend that you find out what kind of wood your decking is made from before choosing the best method for cleaning. 

Class 1 and 2 hardwoods 

These include tropical timbers such as bangkirai and teak, but also robinia and oak. Highly durable, robust and hard-wearing, these woods can be cleaned using a pressure washer with wash brush attachment. 

Class 3 and 4 woods 

This includes softer woods such as beech, spruce and pine. These woods are a little less durable and they are best cleaned manually with a stiff broom and scrubbing brush.

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