Can you pressure wash decking?

dont underestimate mould on your decking

At Savoy Timber, our we know decking and patio care like the back of our hand! One question we’re frequently asked is if you can pressure wash decking. Typically, we’ll only recommend pressure washing your deck as a last resort – once all other options have been exhausted.

The reason is pressure washing a deck may damage it. How? When water hits the wood it slightly expands and then can soaked deeper into the wood causing it to expand, warp, and will break apart the wood fibres. If you pressure wash and then put a sealant on before the wood is dried it can seal in moisture which will lead to rot and other problems.

To help guide you through the process, we’ve put together this guide to help you take proper care of your deck!

Projects that don’t require a pressure washer

Before you begin any cleaning or maintenance project on your deck. Visually inspect it – is it warping? Splintering? Does it have mildew? Cracking? Greying from sun damage or age? Or cupping?

If so, you might need to replace a few boards before you begin work – keep in mind these replacement boards will be a different colour than your existing deck because they are newer and will absorb the treatment differently.

Once you’ve replaced the boards that need it – there are two common projects people often think require a pressure washer but, in practice don’t. The first is cleaning and maintenance, the second is preparing for staining, painting, or sealing.

Cleaning and maintenance

The most obvious scenario which might make you consider pressure washing your deck – is the fact it looks dirty and or grimy. If your deck is dirty, we recommend you start with a simple deck cleaner, scrubber, and a garden hose.

There are two reasons why we suggest you take this approach – cost and it’s less likely you might damage your deck. In terms of cost, you can get a strong deck cleaner for about a fiver and a deck scrubbing kit (broom with strong bristles) for a tenner. So, if you do a bit of shopping around you can get everything you need to clean your deck for under £20.

The cheapest pressure washers start at £50 – £75 and you’ll need to buy or have safety goggles to keep debris out of your eyes.

Staining, painting, sealing, resurfacing

Now, if you’re looking to prep your deck for staining or painting you can use deck cleaner, a scrubber, and hose. You’ll just want to make sure it dries out completely before applying the stain, paint, or sealant.

But, if you’ve tried everything and there’s no other option other than to pressure wash your deck, here’s how to do it property.

Setting up your pressure washer

If you’ve tried the above and still aren’t getting the results you need to finish your project – then it might be time to buy a pressure washer. Particularly if your deck is older or simply isn’t coming clean by other means. Here’s how to get the most out of pressure washing your deck.

Setup and nozzles

Pressure washers come in a range of styles and with a selection of nozzles. The maximum pressure for all pressure washers is measured in bars and should be labeled on the box.

This number tells you how powerful your machine is – we recommend you purchase or have a machine with a maximum of 100-150 bar. This range will ensure you have enough power for soft decking, garden furniture, fencing and other projects without damaging the items.

When setting it up for the first time, we recommend you stick to the lowest setting possible, use a fan tip nozzle, and test the pressure washer in an inconspicuous area.

jet washing decking

Pressure washing accessories

The accessories you’ll likely need for a patio project are simple – a fan tip nozzle for your standard pressure washer lance or if you are looking to invest a bit more – a patio cleaner.

A patio cleaner is a specialise attachment with rotating nozzles which cover more area than a standard lance. Plus, with a patio cleaner you can get a much more even clean than if you use a standard lance with fan tip nozzle.

We find the patio cleaners to be very helpful for cleaning decking evenly, quickly, and with a mostly splash-free cleaning.

There are other accessories like lances (handles), detergents, foam nozzles, brushes, and extension hoses – but you won’t really need those to clean your decking. Although, if you will be using your pressure washer for other projects like washing the car these accessories will come in handy!

Be sure to do some research to make sure the pressure washer you buy has compatible accessories for all the jobs it will need to do!

Pressure washing detergent

You may need to use detergent in some cases, like after a long and damp winter, to remove tough grime. Our best advice when selecting a detergent is to read the label – most are general purpose – though you can find ones that are specifically designed for wood or decking specific.

Techniques for pressure washing

Once you have everything set-up and have tested on a patch area all that’s left is to start pressure washing your deck! We have three tips for pressure washing your deck to minimise the potential for damage.

Go with the grain – Always spray along the grain of the wooden decking rather than across it. Going against the grain can cause damage to your decking and will make the cleaning uneven.

Keep the nozzle an even distance from the decking – Start with your nozzle about 60cm (2 feet) away from your decking boards. You can always move closer if you need. We recommend you never put the nozzle closer than 15cm (6 inches) to the decking as it will damage the boards.

Keep the nozzle moving – The best thing you can do while pressure washing is to take an even pace with the lancer and wave it back and forth in a smooth and controlled motion. You will also need to keep an eye on the time and shouldn’t wash it for too long or hold the lancer in one spot because it could damage the wood.
No matter if you have an old deck or a new deck – a proper cleaning can help lengthen the investment of your decking – so you can enjoy it for years to come!

If you are in market for traditional timber decking, be sure to check out our complete decking kits to help save you time and money! You’ll find exactly what you are looking for here at Savoy Timber, we’ve got a huge range of decking products for you to buy online or in-store. If you have questions or need advice, swing by any of our DIY stores in Preston, Blackpool, or Wigan and our friendly staff will be happy to help!