5 Ways To Damage Your Composite Deck

How To Clean Composite Decking

Bottom line, older TREX, TimberTech, and other wood content composites should be bleached and brightened. Please contact the manufacturer or read the literature that came with your decking if you have any doubts on power washing. A power washer can create serious damage to a composite deck if the pressure is too high, an inappropriate nozzle is used, and/or the nozzle is held too close to the surface. Always start in an inconspicuous area when power washing to test that it is not damaging the decking. The safest course will always be to hand wash your composite decking.

Decking & Railing Duos

We’re going to start with this product which you can buy at WashSafe.com. I then wised up and borrowed this Simpson Pressure Washer from a family member to see how well it would work on my composite deck. I checked with Trex, the manufacturer of my composite decking, to verify if a pressure washer was suitable to use for cleaning purposes before I started.

• The cleaning process will go best if you select the right cleaner to begin with.
• To remove mold from older Trex products, the company recommends using a deck wash that includes detergent and sodium hypochlorite, commonly known as bleach.
• I hate bleach because it kills plants and vegetation and it’s terrible to work with.
• It specifically recommends Olympic Premium Deck Cleaner ($9.98 per gallon at Home Depot) and Expert Chemical’s Composite Deck Cleaner & Enhancer ($19.98 a gallon at expertchemicalinc.com).
• It will kill the mildew spores, but doesn’t necessarily remove them from the surface of the wood.
• Instead, I recommend using DEFY Composite Deck Cleaner.

The Composite Deck Cleaning Process

The best route to take is to hand wash it annually or semi-annually. If you opt to power or pressure wash the decking, you should start using a low psi, at 12 inches or more, with a wide fan-tip in an inconspicuous area. CertainTeed – A pressure washer can be used at 1,500 psi or less with a wide fan-tip at 12 inches or above. Do not pressure wash when mold or mildew are on the surface.

How To Extend The Life Of Your Deck

There are a few situations when it may be okay to use a power washer in your deck. Decks made of ASA, which is essentially a high-end capstock, tend to be a little more forgiving when power washed. Wood and composite decks can also sometimes be cleaned with a power washer, but only if you have a professional doing it. It’s also a bad idea to use a power washer on a composite deck because the power washer can actually take chips out of the composite material.

Design & Price

I make no guarantees on Trex because even they now it will not be 100%. Fred, that’s odd, composite decks shouldn’t have this issue. Maybe try using our Composite Deck Cleaner and see if that takes it off. If you have a pressure washer, maybe give it a light rinsing after allowing the cleaner to set for minutes. To clean a composite deck, sweep it with a broom or leaf blower at least once a week to get rid of dirt and debris. If your deck is still dirty, hose it down, scrub with a brush and soap, then, rinse with a hose. For a faster cleaning option, try using a pressure washer.

Many of the composite companies use wood content in them as well. is referring to was the original TREX which was Red Oak which is a hard wood that leaves a dark black tannin. Anyone who has had to clean off oak leaf stains from concrete can attest to that.

Be very careful so that you use only ammonia free dish soap. Otherwise, if ammonia is mixed with bleach, it can create toxic fumes. Once you’ve blended your mixture, swab it on your deck and rinse it clean with water. Keep a safe distance between the power washer and the deck surface. We recommend staying a minimum of 6” away from the surface. This should be enough to remove any dirt without damaging the composite decking.