How to Pressure Wash Your Decking | 6 Key Steps

Spring is in the air, the time of year for popping on the old marigolds and getting your house all shipshape for the new season, not neglecting to tidy up any outdoor space too. 

If you have garden decking, some traces of winter may be showing on your deckboards, which can normally be removed with some deck power washing. 

Pressure washing a deck can be performed without causing damage if you use the right tools and follow the correct procedures.

Abidance of the tried-and-tested techniques, as we’re about to more exhaustively explain, will leave it looking immaculately clean and safe to negotiate.

You need to be wearing the right gear before you tackle pressure washing a deck, putting on some gloves and goggles to protect your hands and eyes, and non-slip boots on your feet so that you don’t take a tumble on the wet surface. 

Cover any furniture, plants etc. that are nearby with plastic sheeting if you’re keen for water not to make contact with them. 

Then you can begin and we recommend using a medium duty pressure washer with a PSI of 1500-2500 (indicating the force of the water spray), as it has the power to safely loosen and wash away dirt, grime, and algae from UPVC decking and other decking types. 

Start with a 25-Degree Nozzle (Green Tip) for a balanced spray angle, switching to a 40-Degree Nozzle (White Tip) to rinse the surface without leaving behind any streaks. 

On encountering a struggle with stubborn dirt in the boards, try dislodging it with a soft bristle brush after washing and repeating the process.

To get the best results and ensure that your deckboards are left unblemished, it’s crucial that you follow the method of pressure washing a deck to the letter.

There’s a drill of six practical and easy to follow steps for returning decks to a princely condition:

Fail to prepare, prepare to fail, as the old mantra goes.

Your decking layout needs to be free of any obstacles ahead of pressure washing, so any furniture or planters that reside on the deckboards need temporarily shifting elsewhere. Add some plastic sheeting to plants around the decking to avoid them being splashed with water or any spray employed.

Inspect the boards in case of the emergence of cracks in them and check none have come loose, prior to sweeping away any leaves or dirt that have formed.

Crack on then with setting up the pressure washer and attaching the most appropriate nozzle.

It’s a danger to use too much pressure when deck power washing as it can inflict damage, spawn discolouration and water absorption, and leave UPVC and composite materials covered in streaks.

The exact right setting will do the job you want and see that your decking preserves its integrity. 

Set your pressure washer at 1500-2000 PSI for UPVC platforms, 1500-2500 PSI when it involves a composite deck, and 500-1200 PSI to cleanse timber decks. Nozzles of 25° or 40° will prevent surface damage. 

Adjust the pressure level by using the pressure control knob – that’s how to pressure wash a deck without damaging it!

When water doesn’t manage to break down dirt, algae and mildew, you can always try a specialist decking cleaner (ask us for a recommended solution), and once it’s properly soaked (takes 5-10 minutes), undertake the pressure washing process again.

Refrain from using any strong chemicals / bleaches etc. as this will usually cause irreparable damage – soapy water usually does the trick across all deckboards.

Holding the pressure washer nozzle, the ideal technique is to stand at least 30 centimetres away from the decking and move it in smooth, even strokes to stop impairment and streaks occurring. 

Get an even clean by working in the direction of the deckboards and keeping the nozzle at a consistent angle.

The decking will need a thorough rinsing once pressure washing a deck is complete as you don’t want any loosened dirt left behind. 

It will stop decking being slippery and stem the attracting of dirt and grime, something that would take you back to square one more quickly than you anticipated.

Hold off returning your garden furniture to the deck or applying any kind of treatment e.g. sealing a deck after pressure washing, until it has been given at least 24 hours to fully dry, otherwise moisture can get trapped underneath. 

This is a key point to underline for anyone who owns wooden decking as excess moisture is a well-known catalyst for timber decks warping and rotting, and the manifesting of mould growth and structural weakening.

You run a risk of inflicting damage on all decking shapes, materials and types if you choose to ignore the direction given for pressure washing decks. 

By addressing some of the pitfalls of doing this, we hope to deter you from using an improvised strategy outside of the prescribed routine.

Using Too Much Pressure

If a pressure washer is on too high of a setting, it can end up marring protective coatings. Obey the settings outlined earlier in the piece and test on a small area first to check the setting is suitable for the product. 

Holding the Nozzle Too Close

Keep a distance of 30 centimetres between the nozzle and decking or else it can create visible marks and remove sealant. 

Not Rinsing Properly

A failure to rinse after pressure washing may pose a safety risk, as well as make the boards sticky and ignite mildew growth. An even spraying of water will rinse away dirt and debris.

Deep cleaning won’t need to be a frequent undertaking if you heed preventative maintenance tips that keep decks looking tip top. 

In any list of garden decking ideas ought to be the mention of regularly sweeping the surface so that leaves, dirt and debris don’t get a chance to fester and provoke mould and stains. 

Spillages are par for the course when having a few al fresco drinks on garden decks, but so they don’t create a permanent stain, wipe them immediately. 

And once or twice a year, get that pressure washer out to give it a good wash down.

Like hoovering the house, make sweeping your deckboards a weekly job and do it with a soft-bristled brush that is capable of detaching and dismissing debris without scratching the surface. 

An accumulation of debris can be a stimulus for infestation, mould etc., so for a task that will only take a few minutes once a week, it’s well worth doing.

Returning to our earlier point about spillages, large or small, they must be dealt with fast before they manifest into something serious, and you shouldn’t just rely on pressure washing to treat them. 

For a quick touch-up that usually makes them vanish, use a non-abrasive cloth and a soft brush.

Why not bookmark or print off our indispensable guide to pressure washing so that you can refer to it every time your deck needs a good clean. Observe the advice and see it shine again! 

Minimal time needs setting aside for pressure washing if you elect to have our UPVC decking fitted in some section of your garden space as it’s effortless to clean.

Lakeland Verandahs is an authority on lots of subjects relating to outdoor living, not just the topic of pressure washing decking, including the ongoing decking vs patio debate. If we sound like we know our onions and you’d like to employ our expertise, get in touch!