Mold on Trex decking.

Debra K.
by Debra K.
I could use some advice on how to get this off of here. It's also on the treated wood underneath......
Keeps coming back every yr.
  25 answers
  • Wet & Forget Wet & Forget on Jul 02, 2013
    Just spray it on and Wet & Forget absorbs to the surface to keep it clean all year long. Each time it rains the product is reactivated to gently breakup and remove the growth.
  • Debra K. Debra K. on Jul 02, 2013
    Never heard of it....there Is a store near us that carries it.....maybe we'll have to try it!!! How long before you see results??? We were hoping to put an oil base on the wood underneath.....
  • LandlightS LandlightS on Jul 02, 2013
    "Because Wet & Forget's gentle cleaning action uses the wind and rain to continue working overtime" from the "Wet n Forget" site. It is not an immediate cleaner, and they state that it keep working every time it rains. I'm going to one of the few retailers near by,no big box stores, to give it a tryout. In the meantime, I would suggest a cleaner of equal parts of hot water, TSP solution, outdoor bleach and a few drops of liquid dish detergent. (dissolve a couple tablespoons of TSP in 1/3 of the total amount of hot water)....scrub as necessary and you will have a clean deck. Have a great summer.....Gary
  • Barb T Barb T on Jul 03, 2013
    I know what you should NOT do...High pressure water. It will lift the grain and you will have a real mess. Also, do NOT use bleach. I have the same problem with my composite deck. The green is driving me crazy. So much for minimal care! I will be waiting to see how it works.
  • LandlightS LandlightS on Jul 03, 2013
    The info below comes from the Trex is the link....just making it eaiser for you to read. Note that is does mention commercial deck cleaners containing bleach. Where is stat that bleach can "lighten the wood on the surface" they specifically mean NON-DILUTED bleach Nothing like a good old scrub brush, soap and water......Gary May 30, 2013 Mold Technical Bulletin Mold is a lower form of plant life that can settle and grow on any outdoor surface, including Trex® decking. Mildew is a form of mold that grows on damp surfaces. Mold spores are similar to seeds, but cannot be seen until colonies form. Air currents, insects, animals and water transport the spores easily. Due to mold’s adaptability and large number of species, it is very hard to control and impossible to totally eliminate. Mold will not affect the structural performance of Trex decking. In order to form visible colonies, mold needs food, moisture, and temperatures between 40 and 90˚ F. Trex decking is not a food source for mold, but can collect food in the form of dirt and debris such as the overflow from flowerpots and gutters. Trex decking can also supply moisture if the gaps between deck boards are too small or clogged. Refer to Trex decking Usage Guidelines for gapping instructions. How to remove Mold from Trex® Composite & PVC Decking All exterior building materials require cleaning. Trex is no exception. Periodic cleaning of Trex decking will remove dirt and pollen that can feed mold. If mold colonies appear, clean the deck with a commercial deck wash containing a detergent and sodium hypochlorite, commonly known as bleach. This chemical will remove the mold, but please be aware it will also lighten the wood on the surface. If the deck has not been cleaned regularly, it may require several treatments with the deck wash to completely remove all mold colonies. The following brands of deck cleaners have been found to be effective in removing mold from Trex decking:  Olympic® Premium Deck Cleaner*  Expert Chemical™**Composite Deck Cleaner & Enhancer ( Always apply these products to a DRY deck. Applying to a wet deck will significantly reduce the effectiveness of the cleaner. NEVER mix any other cleaners (ammonia, phosphoric acid, etc.) with bleach .  For a non-chlorine based alternative UltraMean®*** can be used, but will require scrubbing with a soft brush immediately after application . Mold occurs readily outdoors and may return in some environments despite proper cleaning and preventative measures. Trex recommends cleaning decking twice a year (spring and fall are good examples). Mold does not damage Trex and will cause no structural harm if allowed to propagate. How to remove Mold from Trex Transcend™ Decking If debris such as pollen and dirt is allowed to remain on the deck surface, mold can feed on the biofilm. Using a hose and warm soapy water with a soft bristle brush (1500psi pressure washer can also be used for basic cleaning, however up to 3100psi pressure washer is allowed for more serious cleaning) is recommended to remove the food source and mold.
  • Debra K. Debra K. on Jul 03, 2013
    Hey, thanks a lot Gary....I used mean green on it a couple yrs ago and Scrubbed it...and it looked is MUCH worse now than before...I'm afraid it will take A lot of elbow grease. Looks like a project for the Very near future, thanks for the recipe above....I wrote it down and may well consider using that.
  • Melissa Gutilla Melissa Gutilla on Jul 03, 2013
    Why would power washing lift the grain? I have the same problem on my Trex deck! I was also thinking about staining mine. I read it on their site and it says it is possible. Have you guys heard of it or seen anyone do it? Let me know Debra how the stuff worked I'm interested myself. If I find something I will let you know also!!
  • Kathytrys Kathytrys on Jul 03, 2013
    I am having mold and moss grow on my Trex deck. I have plants and grass at the edges of the deck plus a dog. So to be more green I was thinking of using vinegar water, a brush and elbow grease. Whaddaya think?
  • Debra K. Debra K. on Jul 04, 2013
    Can't hurt to try...what a pain....let me know...I'd use white vinegar of course.....vinegar is great for a lot of things!!! I imagine it would have to be a pretty strong solution. Did you read the link above from landlights that Gary posted for me???
  • @Melissa Gutilla composite decks are made of resins & wood fibers, you blow the resin off & you now have created a feeding ground for mold. @Debra K. while that could possibly be mold it looks more like mildew - clean per Trex's directions & work on eliminating any potential standing water, make sure water drains out from under the deck etc... Beyond that mildew can & will grow on anything under the right conditions For more on these topics: a look at the issues / current lawsuits & 10 common enemies of a composite deck
  • Dana J Grant Dana J Grant on Jul 04, 2013
    bleach and water will get rid of it. And when it come back spray it again
  • Minuet Stephens Minuet Stephens on Jul 04, 2013
    Its not mold or mildew it's algae. Hydrogen peroxide or oxygen bleach (not chlorine bleach) are the least toxic ways to treat it.
  • KMS Woodworks KMS Woodworks on Jul 04, 2013
    It looks more like Algae than mold or mildew ( which are types of fungi) I would go with a Oxy type cleaner
  • Brenda Nielsen Brenda Nielsen on Jul 04, 2013
    I use this product in my shower (Wet it and Forget it) , once every few weeks I will wipe the tile with a piece of terry cloth to remove any soap or scum residue, no scrubbing and I wipe away anything in the grout but what I do is nothing compared to all the scrubbing I am use to. By the way, it has a tag for dummies, spray when surface is dry then let it do the work.
  • Debra K. Debra K. on Jul 04, 2013
    Thanks Minuet and KMS....I agree. I will buy this product.....
  • Patty A Patty A on Jul 06, 2013
    my TREX deck is completely covered with spotty mildew, algae and mold. I have spent countless hours scrubbing, soaking, power washing name it. Little did I know when I spent the extra money to build this deck that it would be the worst product ever. Nothing works and it has looked awful since its second year....
  • Wet & Forget Wet & Forget on Jul 09, 2013
    Hi Debra, With green algae stains you'll start seeing results within a few days, when it comes to mildew spots or black mold, it'll take a little bit longer but the beauty is that all you have to do is apply the product once and wait for the wind and the rain to take care of the growth on the surface, no scrubbing, no bleach, couldn't be easier.
    comment photo
    comment photo
    • See 2 previous
    • Debra K. Debra K. on Apr 28, 2014
      I will!!!!!! (If it ever stops RAINING.....ugh).
  • Linda Olson Linda Olson on Jul 18, 2013
    I use a solution of dawn( 2 Tablespoons ) dishsoap, 2 cups white vinegar, 4 cups of hot water put it on and Lightly scrub... the green algae comes right off. Spray down with the hose after. looks great. I have tried "deck cleaners" but for algae this really works. Wet and Forget, I haven't tried, it sounds good though if it works on algae.
  • Debra K. Debra K. on Jul 18, 2013
    I know Patty...I haven't tried anything yet....but as soon as I do, and whatever results I get, I will take a before and after and keep everyone posted....
  • Linda DiPierro Linda DiPierro on Jul 31, 2013
    I also have an older Trex deck and I've been using Expert Chemical Composite Deck Cleaner and Enhancer. It's one of the cleaners that Trex recommended on the older Trex deck. It works, but you have to order it on line from Expert Chemicals, Inc. 1-800-831-4963. Hope this helps.
  • Debra K. Debra K. on Jul 31, 2013
    Wow, thanks Linda!!
  • Alice McClelland Alice McClelland on Apr 05, 2015
    I have the white lettuce panels at the bottom of carport. It has like a film on it that looks like a mold? have do I go about getting this clean? thanks
    • Debra K. Debra K. on Apr 05, 2015
      Full strength Simple Green would work great on that..just spray it on and use a scrub brush or some kind of cleaning brush. Brush it real good and hose it off. I use it on all my vinel around my windows, doors works great!!
  • Diana Diana on Aug 23, 2015
    There is a product called WET IT AND FORGET IT that is supposed to work wonders
  • DianaB DianaB on Nov 09, 2015
    I see folks talking about mold here. This is not mold at all.. It is the green algae that forms when there is not enough sunlight to dry the area and kill it off, like the stuff that grows on the north side of trees (that is how you tell which direction north is). It is not harmful, just may not be as aesthetically please as you might like. It will always grow there. Contact the manufacturer for their recommendations. That would have been my first choice anyway--straight from the horse's mouth, so to speak. They know best what the treatment should be. Be sure to show them the photos so they know you are not talking about mold.
  • Edward B. Edward B. on Dec 02, 2015
    The reason the mold keeps coming back is because you are using chemicals like Bleach and Ammonia that look good for a few months but make the mold come back worse every time. The only product I've seen that actually works to keep the mold from coming back is Rhino Hide's mold barrier. I think Trex actually recommends them too. I can't remember the name but you can find it here...