trex_moldIn the past 15 years there has been a substantial amount of composite decking products to hit the market. Some of the more popular are Trex, Azek, and TimberTech. Composite decking is a mixture of recycled plastic and wood fibers. They were designed initially to be maintenance free with no need for cleaning and or an application of a sealer/wood stain.

The industry has since changed from "maintenance free" to" "low maintenance" due to the many issues with mold and mildew. There have been class action lawsuits from this but the fact remains that there is no such thing as "maintenance free" when it comes to horizontal exterior surfaces. It does not matter what the substrate is, all will need periodic cleaning and or sealer.

The question is how should I maintain my Trex or Composite Deck so that it looks good continuously? Well it is an fairly easy process and should be done whenever the mold/mildew becomes noticeable. Failure to clean ASAP could result in the mold spores never coming clean!

We do not suggest bleach for cleaning composite wood. While it does help remove the mold and mildew, it can lighten the wood fibers of the wood in the decking, bleaching out the color. It is best to use a composite deck cleaner that contains sodium percarbonate as the main ingredient. Sodium Percarbonate is registered by the EPA as a mold and mildew remover. It is a very effective chemical and is essentially harmless when it comes in contact with humans and vegetation.

  1. Clean off decking and remove all furniture 20+ feet away from decking.
  2. Use either the Defy Wood Cleaner or the Restore-A-Deck products. Both contain sodium percarbonate and additional surfactants that aid the process of cleaning exterior wood and decking. Both are powdered concentrates.
  3. Mix cleaner in a bucket with water. Warm water if possible will work better. Follow the directions as to how much cleaner you should add per gallon of water.
  4. Apply the cleaner with a pump sprayer or scrub bush. We suggest doing sections of 100-200 square feet at a time.
  5. Using a scrub brush or pressure washer, lightly wash off cleaner, dirt, grime, mold, mildew, and algae. Repeat if needed.
  6. When done thoroughly rinse all decking, house and vegetation.
  7. Optional: Application of a clear water repellent will minimize the mold growth. It is a very easy step. We suggest the SuperSeal-M Water Repellent. It applies with pump sprayer and will not change the appearance at all once dried.
*Update: Another popular option for protection is the Defy Extreme Clear. This product offers even better protection as it contains "zinc oxide". Zinc oxide combats the growth of mold and mildew. In addtion the Defy Extreme Clear will "enhance" the color of the composite wood just slightly, restoring some color back into faded composite wood decking.


Keeping up with the cleaning of your composite deck is essential! It will keep the wood looking better and is healthier choice for people who have allergies.

If you have any questions please use the form below.

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  • We will reply to your comment shortly
    Fran garigiulo · 05/21/2013
    I have. Tre x d elks get a lot of sun and h a ve faded considerably how. Can I restore th e look so it looks better?
    Spent a lot of money and looks terrible thank you
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    The Sealer Store · 12/16/2012
    Sorry but that is not possible to fix.
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    BJ · 12/14/2012
    We have a 6 month old composite deck and some olive oil was dripped on it. I used an on line "home remedy" of baking soda and vinegar to remove the spots but it also faded the color of the decking where I applied the mixture. Help! Is there something I can use to restore or brighten these lighter areas? I just feel awful that I made a bad situation even worse with this "home remedy". Thank you.
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    The Sealer Store · 07/20/2012
    Hard to say. You cannot fix the discoloration from UV fading. What are the stains exactly? Grease, oil, dirt, grime, etc.
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    Larry Scott · 07/20/2012
    In addition to mold stain we have discoloration where furniture has been moved, and other stains from heavy use. It is exposed to direct sun and weather. We just cleaned with "Expert Chemical's Composite Deck Cleaner and Enhancer" but the discoloration is still there and some stains. Your suggestions?

    PS:wish I had found your product first.:sad:
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    The Sealer Store · 05/16/2012
    I am sure you are fine with both.
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    Towns LT · 05/16/2012
    we live in Michigan an my husband insist on shoveling snow off deck is this doing any harm also can you use charcoal when grilling on deck
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    The Sealer Store · 04/03/2012
    You cannot add a clear coat on top of Messmers Composite deck Finish. You could try the Defy Extreme Stain in one of the three tints. It will add color and have the zinc oxide as well. It should absorb into the composite wood just fine. I would only apply one coat.
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    Tom · 04/03/2012
    I have a question about restoring my Trex composite deck. I want to clean the mildew off and apply Messmer's Composite Finish to restore color. Can I then add a coat of the clear zinc finish to "seal it" and prevent mold/mildew from recurring?

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    The Sealer Store · 03/19/2012
    You can add a penetrating stain to Trex. Any of these will work.

    TWP Stains
    Armstrong Clark
    Defy Extreme
    Messmers UV Plus
    Penofin Stains
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    Matt Taylor · 03/19/2012
    My TREX deck has faded from sun and cleaning. Has anyone had success with a penetrating stain to restore color?
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    The Sealer Store · 10/03/2011
    I would try a deck stain stripper ([url][/url]).
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    Rhonda Huseby · 10/03/2011
    Hi -

    I dripped Messmer deck stain on my composite decking. Is there a way to remove the drips?

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    Composite Decking · 06/19/2011
    I agree in industry maintenance free to low maintenance is big issue due to compitation.I just wanna thank you for sharing your information and your site. I’ve learned new about composite decking today. Thanks
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    The Sealer Store · 05/23/2011
    Pressure washing alone does not remove solid stains. Is the stain transparent or a solid color?
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    Linda kaczmar · 05/23/2011
    I just bought this house last Aug. and did not get time to clean the dirt and shingle debre ,mess from the new shingles that the previous owner had replaced. I tried using a course hand brush and water on one board and it came off. However this is a large deck and I do not want to clean the whole deck on my hands and knees. The deck has yellow stain on it that the previous owner had applied on recently. Can you advise me on an easier way to get my deck cleaned? Would a pressure washers take the stain off? Thank you Linda
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    Dave Barnes · 05/14/2011
    Composite decking has become a real hot topic in the industry over the past few years and your advice is "dead-on"...especially with the importance of utilizing an oxygenated bleach cleaner.

    The only popint that I would add is that sealing composite decking, after cleaning, with a clear sealer containing zinc nano-particles, such as Defy Extreme Wood Finish - Crystal Clear, will go a long way in delaying the return of the mildew growth. Zinc has been used in various forms and applications to combat mildew and algea growth and the zinc material in the Defy Extreme nano formula has been tested to perform exceptionally well in that application.
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    The Sealer Store · 05/14/2011
    We personally use it and have customers who can keep the mold off annually or even for 2 years.

    Another option is the Defy Extreme Clear ([url][/url]). It contains "zinc oxide" which is a known mold killer. Works very well.
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    Doug Chapman · 05/14/2011
    I need to pressure wash composite deck 3 times a year to remove black mold spots. It comes off rather easy without the need for any cleaning products such as sodium percarbonate cleaners. However, I am interested in any comments from users trying the SuperSeal-M Water Repellent to see if will reduce the frequency of deck washings.