How to Clean Decking with a Pressure Washer


Pressure washers are a go-to when it comes to cleaning outdoor spaces. From a deck or patio to walls and fences, the force of the water can budge any dirt to get foundations looking as good as new again.

A pressure washer can also be used to clean your decking. But while this may seem a simple task, there are a few things to bear in mind. Decking is more fragile than stone or patio, so the force of the pressure washer needs to be monitored. You do not want to damage the wood.

The material is also likely to expand and contract when it comes into contact with so much water, so you need to be careful it doesn’t split when drying.

A stiff brush and soapy water can do for those in-between times, but after a long, wet winter, a pressure washer may be all that budges moss, algae and wet leaves from the grooves of the decking without back-breaking work.

Pressure washers can work on both timber and composite wood but as mentioned, they can cause more harm than good if used incorrectly. Not to worry – Speedy Services have all you need to know below.

Speedy Services also has all of the tools you need available to hire, which is more cost-effective than buying expensive equipment and also takes away the headache of storing them in between uses.


What you need to pressure wash your decking

The force of the water can be strong. So, as well as all of your cleaning materials, you’re going to need to wear PPE:

  • Safety goggles
  • Gloves
  • Boots (wellingtons will work)
  • Covering clothes

Ensure all skin is covered, particularly feet and legs. It may be nice weather, but flip-flops and shorts should be avoided. Any splashback from the water could be painful, and dirty too. There is also the risk of debris, such as small stones or sticks, being flung into the air.

Gloves will also help when you’re working with the detergent, so none comes into contact with skin. You may prefer rubber gloves when pouring the detergent, and then work gloves when using the pressure washer.

To get the job done, you will need the below tools.

Your pressure washer should be a maximum of 150 bars if you will be using it on decking. This way, it isn’t too powerful for the wood or composite material.


How to clean decking using a power washer


Step 1: Remove furniture and accessories

You need to start with a clear, basic foundation to clean. This doesn’t just minimise damaging seating or décor, but also means absolutely all dirt is removed. If you’re going to hire a tool, you want the job done the first time.

So, remove all furniture, seating, pots, and decoration from the decking to leave you with the plain foundations.


Step 2: Sweep

Before you power wash, you need to sweep away any of the existing removable debris. This includes leaves, old dirt, and other bits which the bad weather may have brought over to your garden.

This will allow the pressure washer to come into contact with the actual ground-in dirt you’re trying to remove from the grooves, as well as prevent potentially dangerous debris from being flung around when you’re working.

It will also reduce the time spent pressure washing, which helps limit the decking from becoming over-saturated and splitting.


Step 3: Apply pre-treatment

A pre-treatment will soften any dirt, making it easier to remove. Again, this will limit how saturated the decking gets. The type of pre-treatment you need will depend on your decking material and how dirty it is, so research beforehand.

Follow the instructions of your pre-treatment. Most will need to be applied and then left for 10-15 minutes to get to work. You may also want to add a cleaning solution to the pressure washer to use with the water, but this isn’t necessary.


Step 4: Test the pressure

Most pressure washers have adjustable pressure settings which give you the right level of power and spraying type. Test the chosen pressure on an inconspicuous section of decking, such as a corner or side, to check it seems okay.

You want it to be powerful enough for cleaning, but not too much to cause damage.

  • SPEEDY TOP TIP: Don’t change the power levels while cleaning. This could result in obvious cleaning marks left behind

Step 5: Start power washing

Once you have the power levels down to a tee and are used to the feel of the washer and how much control it needs, you’re good to go.

Start on your inconspicuous corner, and work in straight lines along the decking. Some tips to think about:

  • Overlap your lines to avoid watermarks and leftover dirt as you move along
  • Keep the nozzle about 15cm away from the decking at all times
  • Try not to pause in one place. This can oversaturate the boards and also cause the grain to fade. Before pressure washing, you need to ensure you won’t be interrupted
  • Keep going with a consistent speed and power level, to get the best results


Step 6: Rinse down

You can do this with the softest setting on the power washer, or a garden hose. Just ensure any debris or detergent left over is removed and use cold water.

You can then grab your brush and push away any remaining puddles of water. This will limit damage to the decking, and also ensure the water doesn’t freeze.


Step 7: Aftercare

When the decking is clean and dry, you may want to repaint it or seal it to protect the wood from weather and use.

You can treat, paint, stain, varnish, or seal wooden decking. You may also want to sand back any rough sections. This won’t need to be done with composite decking, as no maintenance like this is required, but you may still want to check it all over for damage or replacement boards required.



Thank you for reading our Speedy Services blog. We hope you found our guide on how to pressure wash your decking useful.

If you also have a patio, you may want to read our guide on How-To Clean a Patio with a Pressure Washer.

Visit our Skills and Projects page for more DIY tips and tasks, too.

You’ll find all the power tools and hire equipment you need right here, why not start planning your next DIY project today and open a Speedy account online or in-store for all your tool hire needs.



* Image by whekevi from Pixabay

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