How to Properly Clean Your Wood or Composite Deck

Caution! –> What, No Pressure Washer?

Manufacturers of composite decks will tell you to use a soft bristle brush with a mild soap and water solution.  They will in many cases recommend NOT to use a pressure washer, you will even hear this warning for wood decks.  

Any pressure washer used incorrectly can cause damage to the decking material.  Too much pressure, the wrong spray nozzle, the wrong angle, or spraying too close to the wood or composite deck can permanently damage the surface of the deck boards.  However, used properly, pressure washers will make the job much faster, easier and do a much better job than simple scrubbing with a brush.


What Pressure Washer is Best?

For the average home owner, a 3000 PSI electric pressure washer is the best option for many jobs around the house, including deck cleaning.  If you don’t have one, you can rent one, or if you are so inclined to purchase one and would like some advice on what to but, see our post on The Best Pressure Washer for Home Use.

Nozzle Selection:

Almost all residential pressure washers come with 4 spray nozzles which each provide a different spray pattern.  These are 0, 15, 25, and 40 degrees.  The larger the pattern, the lower the delivery pressure will be, so for deck washing, always use the largest spray pattern nozzle you have, this will usually be the 40-degree nozzle, which will typically be colored white.

Prep the Deck and Surrounding Area

Use a leaf blower or sweep the deck clear of larger debris, such as leaves.  Then cover any plants or shrubs that are close to the deck that may see any over spray from the pressure washer. 

Select a Deck Cleaning Solution:

There are deck cleaning solutions that are safe for plants and shrubs, but I still feel it’s a good idea to cover your sensitive shrubs around your deck.  Choose a high-quality solution that is appropriate for your deck type and application.  Bob Vila has an excellent description of these cleaners here

Soap the deck, handrails, and balusters with a generous amount of cleaning solution and let it sit for a few minutes to allow it to penetrate and loosen the dirt before pressure washing.  However, don’t allow it to dry, so if you have a large deck, only do as much as you will be able to wash and rinse before drying.  If it’s a hot sunny day, the solution will dry much faster, so keep this in mind.

Pressure washer Caution:

We discussed using the largest spray pattern nozzle that comes with your pressure washer, now how to use it.   Use a sweeping motion going back and forth.  Never get the tip of the spray wand closer than 8” to 10” from the deck surface, and keep the spray at a 45 degree angle to the deck boards. 

Start High and Work Your way down.  Start with handrails, then balusters, then deck boards.  Before you start, plan your attack.  Start in an area of the deck where you can continuously move outward so as not to have to walk over a wet cleaned area.

Let it completely dry:

Let the deck completely dry before replacing furniture

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