How To Pressure Wash A Wood Deck

Sometimes, you just want to be using the pressure washer because it’s just so much fun right? You’ve washed the car, the drive, all of the garden furniture, the patio, the side of the house, the fences and even the boats had a wash too. You look around and notice the wooden decking, eureka! Something else to be pressure washed.

Over time wood changes colour gets stains and generally looks unattractive. So it makes sense to clean it, right? Plus it’s another opportunity to use the pressure washer.

Is It Safe To Pressure Wash  Wood Decking?

There are some “experts” that claim using a pressure washer on wood can damage the wood and render it useless. Why? Because they don’t give us the credit of rational thinking, and careful usage. Let’s have a look at why they think it’s a bad thing.

Why Wood And Water Don’t Mix Well

It is true that if wood is exposed to too much water, it damages the wood. You only have to look at an old piece of plywood that’s sat in the garden for a few months to know that’s the truth. But why does water damage wood?

As the wood absorbs the water, the wood expands causing internal fibres to break apart. This weakens the integral structure of the wood and allows fungal or viral diseases into the wood that cause it to degrade. Even treated wood will degrade over time and this is why we’re told not to use high-pressure water to clean our decking.

How To Safely Clean Wooden Decking Using A Pressure Washer

Now that we’ve looked at the whys and why not’s of using a pressure washer on decking let’s get into the how. The first thing you need to determine is what type of wood your decking is constructed of. Softwoods like pine cannot withstand more than 500 to 600 Pounds per Square inch of pressure(PSi). 

Hardwoods can stand more pressure but you should never use more than 1200 PSi on any wood. Whatever type of wood your decking is constructed from, it’s important not to concentrate the water jet onto one area for too long. Always use sweeping motions with the wand to minimise the risk of damaging the wood.

Personal Safety

Water from a pressure washer is capable of inflicting serious injury to human skin, so always think about your safety and the safety of those around you. Wear eye protectors, keep arms and legs covered (no shorts or tee shirts). Wear boots or at the very least closed in shoes (no open-toed sandals or flip flops).

Pressure Washing Wooden Decking In 8 Easy Steps 

To clean your wooden decking safely and efficiently follow our easy step by step guide.

  1. Clear the deck
    Remove any pot plants, furniture, ornaments etc from the area you want to clean.
  2. Sweep clean
    Using a stiff yard broom remove all loose dirt and debris.
  3. Power up
    Start your pressure washer in the usual way ensuring there are no air blocks or kinks in the hose etc.
  4. Add detergent
    If you’re using a detergent be sure it’s a specially designed detergent for using on wood and that it’s compatible with your pressure washer.
  5. Soap up
    Using the detergent nozzle (black) apply the detergent to the decking. Allow to work in for around 5 to 10 minutes or as directed on the bottle.
  6. Rinse
    Change to the white nozzle and remove all of the soap suds this should also remove any stains etc from the wooden decking. Be sure to use the lowest power level that’s appropriate for cleaning wood.
  7. Allow to dry
    Once the decking has been cleaned and thoroughly rinsed, allow it to completely dry out (48 hours in perfect conditions).
  8. Treat the wood
    After the wood has fully dried out apply a sealant or varnish to the wood to protect it.

It is important to be sure the wood is completely dried out because any moisture trapped inside the wood after sealing will cause rotting. Allow a longer drying period for safety if possible.

How Often Should Wooden Decking Be Pressure Washed?

Pressure washing wooden decking makes a real difference to the appearance of the decking. You might be tempted to wash it regularly, we urge you to resist that temptation. As long as you’ve washed the decking correctly, allowed it to dry out completely, and sealed or stained it sufficiently, decking will only need pressure washing once a year. Any more and you will run the risk of damaging the wood.

Frequently Asked Questions

Can you pressure wash stain off a deck?

Wood stain can be pressure washed off a deck as long as you use low pressure and don’t concentrate the water onto one area.

What is the best pressure washer for wooden decking?

The best pressure washer for cleaning wood decking is any pressure washer that has the correct PSi for the type of wood your cleaning. To see our top pressure washer picks, click here.

Is pressure washing a deck bad?

Pressure washing a deck is not bad as long as you are careful, and use the correct pressure and nozzle.

How long after pressure washing a deck can you stain it?

In perfect conditions, you can stain a deck 48 hours after pressure washing. Allow longer in colder temperatures.

How many PSI Do I need to pressure wash a deck?

The correct PSi you need for pressure washing a deck depends on the type of wood the deck is made from. Softwoods should have no more than 600 PSi and hardwoods no more than 1200 PSi.

What’s the best way to apply deck sealer?

The best way to apply deck sealant is with a brush. Using a brush ensures you can get sealant into all the nooks and crannies of the decking.

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