Got rid of the mildew on my Trex deck

livvysmomOctober 24, 2005

Since it almost Nov and our 15 month old deck had mold on it -- it was time to try and clean it. Some areas were worse then others -- having a real "leopard" look to it.

Bleach is what you need -- we bought a Behr brand cleaner at home depot and put it in a garden/deck sprayer. Spray it on, wait a few minutes and use a push broom to lightly scrub. Then rinse well. Some really bad areas took longer. All the mold is completely gone now.

Cleaning it cost $4 and 2 hours time. Sure does beat spending $350 to have it sanded, stained and sealed every other year.

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My father-in-law has red, 12 month old Trex decking (replaced his 14 year old PT pine), and has yet to fully remove the mildew/mold. I'll tell him about your positive experience - thanks.

- Wade

    Bookmark   November 4, 2005 at 5:30PM
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The only thing is a fake deck will cost you twice as much as say cypress. So if you deck would have cost 4 grand in wood it's 8 grand in composite. That additional 4000 would last you about 8 reseals factoring in inflation. That's 16 years with a maintenance shcedule of every two years. Composites look like crap in ten. It still comes down to personal preference.

Wade, most times on a composite deck it's harder to get rid of mold. Your F-I-L needs to apply bleach and some Dawn dish luquid and scrub it with a brush.

    Bookmark   November 4, 2005 at 8:19PM
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Behr multi surface cleaner worked amazingly well took no time and no scrubbing. I love my deck again!! Also tried the outdoor bleach which worked mixed 1:1 but smelled bad and had to sit for 10 minutes. The Behr product did not smell as much and worked quicker.

    Bookmark   November 21, 2005 at 6:55AM
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Where do you folks live?
Is the Trex deck in shade part of the day?
I gets wet from the pool?

    Bookmark   September 25, 2006 at 2:49PM
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The Trex website explains all about cleaning it. It is not a maintenance-free material. It IS a color tone-free, wet on wet-free, still tacky-free, crappy orange-free, mold under the finish-free, have to strip-free, have to redo it again-free, fuzz-free, split-free, Amazonian rain forest-free, have to try to find correct information-free, new-age REAL deck material, that I'm betting will hold up better to the elements than any organic wood over the long run.
Now that she has it clean, PP, maybe you could advise her on how to seal it.

    Bookmark   September 25, 2006 at 3:51PM
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YO Srercrcr,,I am picking up on you are wanting to make a Bet, in fact your betting now,,you woudent want to put some money on that bet would ya?? trex vers ipe both fastened the same way no finish,both layed out behind my shop. Or better yet say 2' boards/planks 5/4'' material with 2' stuck in the ground that would speed up me geting my money.$1000 straight up odds, one year time span,judging with a break test on the day of instalation,same break test one year later. I know a meat eating lawyer who will hold the money. You get full access to the testing device and the test area. Gunna put your $ where your mouth is? J

    Bookmark   September 25, 2006 at 5:53PM
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Funny how you didn't dispute all the negatives of wood decking material. Hmmmmm. Indulge me....crooked board-free, cupping-free, split board-free, checking-free, splinter-free.....just have to read all the posts from people with ipe/cedar deck and finish problems. Somebody ought to get a class-action lawsuit going! Once in a rare while you get a composite problem, seems like it's always spots...easily cleaned, can't clean a spot under a finished ipe board. Either live with it or....yep, pay the man to refinish the deck again (Didn't we just do that last year?)
I'm happy to report a one-year old Trex deck, no problems, no sagging on 16"OC as one "professional"'s beautiful.

    Bookmark   September 25, 2006 at 7:33PM
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Thats what I was thinking all talk and no action,or mabey you just used the wrong word you ment ..I think,,or mabey, or it could be,,not I am betting. Belive it man I dont joke with money. You and T=junk will probley be very happy with each other. J

    Bookmark   September 26, 2006 at 5:01PM
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Yep, probley! Translation for all you other fine folks...probably.

    Bookmark   September 26, 2006 at 5:54PM
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Chlorine Bleach or Sodium Hypochlorite (active ingredient in Chlorine Bleach) based deck cleaners that the uneducated recommend may appear to quickly remove mildew (white in color) and mold (black and other colors) fungus from Trex and other Composite Decking. Nothing could be farther from the truth.

The Environmental Protection Agency (EPA) and the Occupational Safety & Health Administration (OSHA) DO NOT RECOMMEND Chlorine Bleach for Mold (Mildew is a species of Mold) remediation on porous surfaces such as Trex and other composite decking.

The reason for this is that Chlorine Bleach does not remove or kill the roots (mycelium) of the fungus, but actually waters them. A few weeks after you have cleaned a deck with chlorine bleach or sodium hypochlorite based products you will notice the mildew or other mold fungus growing back in greater numbers, especially after additional moisture comes into contact with the deck. It will make the problem worse and harder to remove the next time the composite surface becomes unsightly.

In addition, Chlorine Bleach products reek havoc on the rest of the deck structure shortening the life of the entire structure. It is highly corrosive to any metal including structural connectors or fasteners (screws) holding the deck together. It shortens the life of the pressure treated lumber supporting the deck. This could lead to liability issues for the owner of the property and any company who recommends its use.

PRODUCTS THAT CONTAIN SODIUM HYPOCHLORITE ARE ENVIRONMENTALLY DESTRUCTIVE. It is shocking that Trex and other composite manufacturers do not follow the recommendations of the EPA or OSHA and recommend one of the most TOXIC chemicals known to this earth but sell their products as ECO FRIENDLY.

    Bookmark   March 16, 2007 at 10:03PM
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I used a product called Corte Clean. It worked great for cleaning my old Trex Deck. It worked far better than anything I have tried and over the years. I have tried them all. Best part is that it is an environmentally friendly. It did not smell like chlorine bleach like other products and keeps the mold away for longer than anything else. Nor did not kill all the plants around my deck.

    Bookmark   March 25, 2007 at 2:51AM
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CorteClean is sodium percarbonate-based - I believe PressurePros recommends this material.
In my experience, cleaning is one thing and preventing mildew is another. If you get mildew on your deck, it probably means that there is mildew around, and it will come back. There seem to be more and more anti-mildew products around, which is a good thing. One that I have tried with good results is Anti-Growth, but there may be others.

    Bookmark   March 26, 2007 at 2:02PM
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Lary will you just get off it!!! John

    Bookmark   March 26, 2007 at 7:12PM
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You mentioned Anti-Growth. This is an Environmental Protection Agency (EPA) Registered Pesticide and can not be legally used for any purpose not stated on the products label directions.

Anti-Growth is not recommended for composites or anything plastic on their products label directions. They specifically state what surfaces and materials it will be effective on including "Decking" made out of the following "stone", "concrete", "wood", "painted surfaces" or "brick & pavers" and do not say anything about plastic. The Anti-Growth® MSDS can be found @ . EPA REG. NO. 73873-1 It is for NON-POROUS surfaces unlike Trex and other composites. To use this product on TREX and other composites violates EPA Federal Laws. Plus, it is so toxic, they no longer sell it to the general public (see their web site). I can't believe Trex and other composite manufacturers negligently recommend this product.

This is almost as bad as their recommendation of PSC-Solutions Composite Deck Restorer that has unsuspecting customers endangering themselves and violating EPA Federal Laws by mixing "Bleach" with "Ammonium" that is made from AMMONIA (see their MSDS @

See what the EPA & OSHA say about mold remediation and mixing chlorine bleach (sodium hypochlorite is the Active Ingredient) with ammonia @ &

THIS IS ILLEGAL, EXTREMELY TOXIC, CAN KILL, NOT PROVEN EFFECTIVE FOR MOLD REMEDIATION & will only make a Mildew or Mold problem worse and grow back to a greater degree.

Mixing Chlorine Bleach, a EPA Registered Biocide & Pesticide, with anything other than water or using it for anything not stated on its label directions is Illegal and that fact is stated on the label of products like Clorox Regular

"Directions for Use: It is a violation of Federal law to use this product in a manner inconsistent with its labeling."

Ultra Clorox says the same thing. (see MSDS @ ). Nothing on these products labels has anything to do with porous surfaces such as composite decking. You can look up what they are approved effective for by looking up the EPA REG. NO. They are not proven effective for any porous surface like Trex or other brands of composite decking.

Clorox Regular EPA Reg. No. 5813-50" is for; "EPA Registered Tuberculocide Products.

Ultra Clorox EPA REG. NO. 67619-8 (Corox Outdoor also uses this #???, see their MSDS)

The most relevant pages for fungus are pages 23, 25, 39 for fungus applications).

What are these companies thinking? Hopefully no person, pets, or wild life is injured or killed due to these insane recommendations of toxic chemicals.

    Bookmark   March 27, 2007 at 2:00AM
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I didn't know that. Hmmm.
I guess the point that I'm trying to make is that cleaning the deck is one thing, and inhibiting mildew is another. I know a lot of countertop cleaners (Lysol, 409) include an antimicrobial (sometimes with in combination with chlorine bleach and sometimes not), would any of those products work?
I have also seen an Olympic-brand antimicrobial deck wash in the big box store but I haven't tried it yet.

    Bookmark   March 28, 2007 at 7:24AM
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I would think there would be less of a mold issue if the deck was in a mostly sunny area. Are the majority of the decks with mold issues in shade areas or very moist climates? also I would think the cost of refinishing a less than typical size deck say 1500-2000sqf would make the trex a better deal. any comments.

    Bookmark   April 2, 2007 at 9:37AM
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Actually, from the calls I have gone out on,and a couple of posts on this site, trex molds up in the sun or the shade. Its got to be a batch problem or they could not stay in business. The Gamble with t=junk is not worth it to me, but hey!! if you think it is with a big project like that....go draw on an inside straight. J

    Bookmark   April 2, 2007 at 8:10PM
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I installed Brasilia Trex Decking June 2006. It was fine the first year, and just a few weeks ago, the black spots of mold (I guess!) have taken over. I live in Michigan and my yard has some trees. It appears that the mold spots are coming out from the inside --is that possible? I clean it with soap and hot water at least monthly in summer and rinse it well.

When I called Tres they acted like they had never heard of this before.

Does anyone else have Brasilia? Know what works? Know how to talk to Trex?

    Bookmark   August 26, 2007 at 5:15PM
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Nancy there is a post with pictures of trex brasila mold on this site. It is coming from inside the junk,not only has trex heard this before they are still paying off a class action for the same thing. The only way to talk to the t=junk guys is with a lawyer the last time it took 10 years of stonewalling for anyone to get the little action they finally got. John

    Bookmark   August 26, 2007 at 6:07PM
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Thanks for answering so quickly. It sure looks like it is coming from the inside. I have a wood fence and wooden benches in my yard that are in the shade and none of them look like the deck! Trex called me back and said they were sending a Warranty Claim packet......we'll see.

I saw your website; very nice. Too bad I'm in Michigan..

Thanks much.

    Bookmark   August 27, 2007 at 6:22PM
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Isn't Clorox used on clothing, white sheets, towels, other cotton goods, etc.? Aren't these pourus surfaces that actually come in contact with people's skin all day long? If the stuff is that toxic, what am I missing? By the way, I'm not advocating Trex or other composites over wood---that seems to be a personal choice---but it's amazing to me how many people rail on composites and won't admit to the multiple shortcomings of wood. We had a pressure treated wood (Grade A-1 wood, yada yada yada) deck built and in less than a year, handrails and spindles were warping and twisting, cracks appeared on the supports (the surface cracks didn't compromise the strength or integrity of the
wood, but didn't look that great) and I've seen older decks with lots of splinters on the hand rails and decking---even algea or some other growth on it too. My point is not that composite is better or that no one should use wood---it's just that both have their strengths and weaknesses and if someone is so partial that they do nothing but condemn composite, I question the validity of their arguments. I've seen internet opinions against composite written by people who profit on selling wood.

    Bookmark   August 28, 2007 at 2:53PM
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Its a bad deal Nancy. Before tjunk finally got nailed with the class on one hand they blasted out No Maintaince Never Needs Sealing on the flip side they offered to sell a sealer to the really mad Wallets with the same mold going on you have. Good fortune with your claim.

Its a bad idea to use pt wood for decking/rail system. Nothing can change the nature of yellow pine exposed to the sun,rain,weather exchanges. It makes 0 differance far as the grade goes with pt material down the road exposed to the weather no matter how it fastened or what finish is used. This material began its life as framing lumber,this is the best use for it. It should not be marketed as decking/rail, but its soooo easy to sell and its really cheep.

Mold and Mildew will grow on anything left out side with that as a given the idea that man made material is less maiantance than wood exists only in the claims of composite advertising with trex taking the lead.

Being patial has nothing to do with it. Field experance has shown me the problems with composite including a 5 year old choice decking project of mine that is completly crumbling apart with Folks steping thru it. This is not my problem I did what I contracted to do but the Wallet of that Condo is coming up with a big fat chunk of change to redo it.

I am sure at some date man made decking/rail will be as good as an ipe project. But that day is not now right now the Wallet is the bata test. John

    Bookmark   August 28, 2007 at 7:01PM
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What about the 100% plastic option, like ProCell? Is that a better choice than the composites made with plastic and wood flour? For appearance, the Fiberon Tropics looks the best to me. From a distance, it really looks like imported tropical wood. Even up close, it has nice color changes/shading that looks convincing. The ProCell looks more synthetic and I guess it is---but it could pass for painted wood, like someone would use on an old dock. I scratched the Fiberon Tropics sample relatively easily but had a hard time marking up the ProCell piece. I guess mild scratching on the Tropics can probably be filled in by brown shoe polish and blended away and over time, consistent scratching and fading isn't that undesireable---might make it look more authentic. But I wonder if the durability is compromised? For me, it's not the expense, but the bother of having to constantly seal/weatherproof wood that makes composite a strong choice. Also, I don't like the splintering aspect of wood.

    Bookmark   August 29, 2007 at 5:49PM
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Just found this post after a very unsatisfactory claim process with TREX. It's bad enough to go through all of that nonsense of copying invoices, title to house, pictures, words but then to get a "it is an environmental problem and it is not covered" letter really boiled me.

The deck was finished in June 2005. Within a year we started getting these blotchy dark spots. We couldn't believe that it was mold or mildew since we live in Northwest Arkansas where the summer temperatures on our southern exposed deck are in the 80's to mid/high 90's from Mid May through September. There is a fair amount of humidity year round but only 2-2.5 months of winter and almost no snow.

I have power washed with a low power electric washer and Krud Cutter and after that did nothing applied Behr Multi Surface Cleaner and power washed, the only recommended TREX cleaner I could find anywhere including Lowes and Home Depot. Seems like the spotting actually got worse and is very pervasive.

The TREX Claims Representative in his denial letter suggested that I use Expert Chemical Composite Deck Cleaner and Enhancer and offered a 25% discount. His manager on a later call said to also use a soft brush with it. He then really made me mad by saying that I may have to do this multiple times.

I heard the word class action suit. Do you know that as of February 2008 AERT, the maker of ChoiceDeck and located locally, is also being sued because their boards "develop extensive and recurring mold and mildew stains"?

Any thoughts?

    Bookmark   April 10, 2008 at 1:49PM
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Choice is the latest class they are defentley going ahead with it. With the T=junk class they did the same thing to their customers offered to sell a cleaner with info on a sealer while at the same time adverstising both of these would not be needed. John.

    Bookmark   April 10, 2008 at 9:33PM
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John Hyatt, I would like to post a picture of my deck problem. I believe that you mentioned seeing one on another forum. An email to the web site guy didn't provide a way to do this. Can you help me to fo this? Which Forum would be best?


    Bookmark   April 21, 2008 at 1:24PM
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One set of pictures is on this site do a search for trex braxila spots anyone or something like that. This Guy has a link to his site will all the t=junk problems you might get with him. J.

    Bookmark   April 21, 2008 at 3:51PM
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Our deck faces West and gets full afternoon sun. The mold/spotting only occurs on the part on the north end of the deck. Even then, it is not that bad. A once a year cleaning takes care of it.

I don't think the mold is nearly as much an issue if your deck quickly gets dried out from the sun after a rain.

    Bookmark   April 30, 2008 at 7:50PM
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I have had a trex deck for about 4 years now and I gotta say it looks fine. I do not notice any mold at all. Maybe I am just lucky but I have had a good experience with it.

    Bookmark   May 1, 2008 at 8:42AM
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Our experience is similar to Jerryd_2008 posted Apr 10,08
I have done some research on the Trex problem. They know they had some bad batches. Most people just give up. Our attorney said it would be too expensive to fight. I would be willing to initiate another class action lawsuit. They should not get away with this. They told us it was environmental also. Then why did our next door neighbor's trex installed the same year as ours not do the same thing!!!. I am ready to stand outside the retailers with a sign and pictures to warn people BEFORE they purchase this expensive problem!!

    Bookmark   June 23, 2008 at 2:22PM
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I'm fighting the mold also. My deck is three years old and after the heavy snows in Wisconsin this year my deck was spotted with mold. It is totally southern exposure, with only small trees - so no shade at all. I'd be willing to fight also.

    Bookmark   June 24, 2008 at 11:33AM
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Earlier this year, I got nowhere with Trex. They gave me a 25% off coupon for some extremely expensive deck cleaner called Expert Chemical Composite Deck Cleaner and Enhancer only available by mail. Their web site describes 3 passes over the deck with the cleaner and the use of a brush to scrub. This process results in only 100 square feet coverage per gallon that costs like $17/gallon. My two-level deck with stairs is close to 600 square feet not counting the seats and railings.

I was NOT happy since I already used their recommended cleaner, Behr Multi Surface Cleaner, that did NO good. It did however cost only a fraction of the above cleaner. I do NOT recommend it using the allowed low power pressure washer and cold water. I did not see anywhere in the Trex MOLD TECHNICAL BULLETIN that a brush is required.

We are in Northwest Arkansas and the deck has an extreme southern exposure. We are still having difficulty accepting that this is mold or mildew since the temperatures get quite hot for a number of months every year. My wife even thinks that the spotting is worse in the direct sunlight.

Would somebody please explain to me where the Corte Clean Environmentally Friendly Composite Deck Cleaner at mentioned in other posts came from. I see no such product mentioned in my Trex MOLD TECHNICAL BULLETIN.

At this point, I too would like to explore any class action suit others are pulling together.

Jerry D

    Bookmark   June 24, 2008 at 11:52AM
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My deck is roughly 200 square feet not counting railings. So maybe I should look into this cleaner. This is much cheaper than replacing it.

Here is my situation-
I have washed mine twice now, with Thompsons that my builder recommended.
The color is considerably lighter. I have gotten most of the spots - but they are winning.

The surface seems to be more "open" than before. Is there a way to re stain it and seal it? Has anyone done this? I am a single woman with little to no outside experience. I just want to make sure the deck lasts because I can't afford to replace it. I'm willing to do the work I just need to know if it is worth it or will I still need to replace it.

    Bookmark   June 24, 2008 at 1:26PM
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Ejdi,it is possible to put a finish on the soft composits. The more you clean t=junk the more the top layer is damaged so your right the material is more open.

I have used twp116 on soft composite with good results. J.

    Bookmark   June 24, 2008 at 6:54PM
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Thanks John-
The friendly guy at the big box store suggested I lightly sand the deck first to get it smoothed out. I tried a small section and it looks much better. Would you recommend finishing the sanding and then applying the twp116?

    Bookmark   June 27, 2008 at 11:13AM
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EJ,just try it at this point there is very little to lose, a very light even sanding say with an orbital with 80 grit pads might just help. The t=junk material will soak up the twp finish so put a light coat on and just see how it works. You might want to back the first coat up with another in a week or so try a test area but really its not all that hard.

I have done the twp thing with Choice decking,another one in trouble, with good results far as the top goes but of course its not going to help underneith at all. The Stuff and the Co are just total SH##T !! This treatment might get you thru a few years. John Mon

    Bookmark   June 27, 2008 at 7:14PM
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If you sub out the deck work for your landscape customers, why do you let them think that the composites are maintenance free. It's your job to educate them so that they don't spend thousand$ on garbage.


    Bookmark   October 27, 2008 at 4:18PM
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Even though we make the customer aware that the composite products are not maintenance free and that there are other alternative products, comparing to what they had they feel That this is a better choice. It seems that these composites have Improved since they first came out and especially in regards to the colors,textures and options for railings. This is what they want.Our higher end customers in most cases chose wood. In my mind there is no such thing as maintenance free,for any one to believe that, is just fooling them selves. It is only a matter of time and conditions that varies this issue.


    Bookmark   October 27, 2008 at 6:45PM
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john, So you wouldn't try something that could perform better and last long for you customers, then what you currently recommend? jlh1

    Bookmark   October 29, 2008 at 6:45PM
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Lifetime,onetime are both flags for snake oil. We have been thru this before over here its defentley not new but I did get a big grin over it. J.

    Bookmark   October 30, 2008 at 7:42AM
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Finally after over a year of trying to clean the mold off my deck, I found somthing that actually works and works very well. Mold Armor, purchased at Home Depot.
I've tried water+bleach, bleach, and Behr's Premium Deck Wash stain remover. Nothing has worked made any noticable difference untill I tried one last time with the Mold Armor. It worked!! See the photos in the link. I put it on with no water, just took the cap off the container and poored it on the deck, then used a broom to brush it around and spread it out. About 1 minute later the mold was gone, no more black spots.

Here is a link that might be useful: Photo Bucket

    Bookmark   August 2, 2010 at 4:28PM
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Just to clarify, is this a problem unique to Trex decking and not other composites? We are about to build a deck with Timbertech decking and the cost is outrageous, but it's worth it for a reduction in maintenance over the long term, if that is indeed the case. This situation with trex decking would be a deal breaker for me.

    Bookmark   August 3, 2010 at 4:08PM
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Thanks, John.

    Bookmark   August 4, 2010 at 3:20PM
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Hueyd, did you use the Mold Armor "mold and mildew stain remover" or the "deck cleaner" -- or both? Thanks!

    Bookmark   August 7, 2010 at 4:19PM
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Sorry for the late reply I have been very busy lately. Yes, go to the photos in the link provided in my post. I used Molde Armor "Mold and mildew stain remover" and I use their "Deck Wash". The Mold and mildew stain remover I used full strenght, which is how it is suppose to be used. The Deck Wash comes with a hose attachment so it can be mixed with water when you apply it. The Deck wash didn't work for me when I used it as instructed. Instead I removed the hose attachment and poured the liquid, in small amounts, on the deck, brushed it around with a broom, let it set for 1-2 minutes then washed it off.

    Bookmark   September 2, 2010 at 7:45PM
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Our new Trex deck displayed mold after the first Wisconsin winter. I contacted Trex regarding cleaning the deck. They recommended a warm water, bleach and detergent solution with light scrubbing. The mold pretty much laughed at me with no visible results whatsoever.

I power washed the deck making it look brand new, but the mold appeared again within weeks. I recently applied TrueValues Home & Deck Wash, No Scrub Formula. The mold spots disappeared within seconds. I don't anticipate this totally removed the problem so I am going to apply another application in one week. I will post here again to let you know my results. FYI I found the easiest way to apply the deck cleaner was with a spray bottle. It takes a little bit of time, but there is minimal solution wasted.

If this doesn't work, I'm going to replace the entire deck. I'll also be sure to recommend no one use Trex decking materials. After all I've read online, and there was quite a bit, I'm convinced that Trex is not maintenance free, and also susceptible to mold that can not be permanently removed. If there was a legitimate solution to this problem, Trex would have addressed it or someone would have posted a permanent working solution.

    Bookmark   October 18, 2010 at 9:22PM
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Thats a pretty good deal, could save one unhappy composite owner a fairly good chunk of change. I use them as my supplier for a good portion of my jobs, especially when they offer the free shipping specials.

    Bookmark   November 2, 2010 at 12:06PM
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Hi jzabkowicz,

I am a representative of Trex. Warm water, detergent, and a light scrubbing are great recommendations for a general cleaning of Trex, to rid it of dirt and debris. Since you have mold, we suggest the following:

Clean the entire deck with a deck wash containing detergent and sodium hypochlorite, commonly known as bleach. This deck wash will lighten the wood on the surface of Trex in addition to removing the mold. To minimize lightening of darker Trex colors, dilute deck wash with 50% water.

TIP: Cleaners work best when decking is completely dry.

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 (

***Follow all package directions for usage, safety and disposal. NEVER mix any other cleaners ammonia, phosphoric acid, etc.) with bleach.

- Non-chlorine based alternative UltraMean can be used but will require scrubbing
with a soft brush immediately after application. (

- Eco-friendly (no bleach): Corte-Clean Composite Deck Cleaner (

Please feel free to contact me with additional questions or concerns at 1-800-BUY-TREX or


    Bookmark   November 5, 2010 at 1:08PM
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It figures someone from trex would recomend using bleach to clean it.

Bleach will break down the cellular walls in wood, another words it will damage your deck frame. I've seen it first hand when replacing decking on a redwood deck 3 summers ago. The homeowner cleaned the spa walls with bleach. Everywhere around the spa the you could see that the wood was damaged, looked like the wood was rotting, tops of the joist too.

Besides that bleach is not the solution to get rid of mold, it will only come back x2 after using bleach. I know this first hand also cause I installed a tred deck back in '02 for a guy who works at my supply house. It got molding within the first year & only got worst after cleaning it with bleach.

Probably the best thing to do is to stain/seal your trex deck after cleaning it with an approved composite cleaner. This will keep the exposed wood fibers from absorbing moisture, the root cause of moldy trex.

    Bookmark   November 5, 2010 at 1:58PM
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Hey trex lady,

Why does your product turn to dust when exposed to the sun for 5 years?

Can you prove the decomposed dust from your products are safe for people and the environment?

    Bookmark   November 5, 2010 at 5:29PM
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I would be happy to discuss your questions or concerns. Feel free to contact me directly at 1-800-BUY-TREX or


    Bookmark   November 18, 2010 at 5:19PM
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That's crap.
To me its a given the mold isssue will never go away. However it can be controlled. Use olympic deck cleaner pump spray it on, wait 15 mins, hose it off.
Do it every year. Give it a try before the Nazi anti composite Gestappo squad convinces you to tear up your deck and install their favorite brand.
It will cost you $25.00 to see if I am wrong, otherwise fall in for the propaganda and spend your money.
I have said in many post; even you feet and your car need ocassional washing, Should that prove too be too much effort than keep detroits economy strong and buy a car every 6 months, have your feet amputated because there will be mold growing on those if you don't wash them. $25.00 is it too much to try. Unreal..... sometimes I think there are manufactures reps here posing as builders on this site.
steve scholl

    Bookmark   February 6, 2011 at 1:01AM
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I got composite decking in San Diego area and need to clean mold/mildew. Came across this informative thread trying to decide on which product to use. I found elsewhere people had good experience with Wet and Forget. I like it also that it requires no scrubbing and seems to be easier on the environment. Also some good review for it on Amazon.

Does anyone have any experience with it?

Other products I am considering:
- Expert Chemical Composite Deck Cleaner and Enhancer
- Moldex Deck! Concentrated Cleaner
- Mold Armor (don't see a concentrate I can use for my garden pump sprayer)
- Corte Clean

Here is a link that might be useful: Wet and Forget on Amazon

    Bookmark   April 17, 2011 at 8:35PM
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I am considering Trex Decking and read the messages on the mold on the composite decks. I was looking at a new product that states that it is mold resistant. Has anyone invested in the new materials with any success?


    Bookmark   June 24, 2011 at 8:33PM
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When I built the deck on the north side of my house I was concerned about mold so I ended up going with PVC decking. Maybe if you told us what product(s) you are looking at someone here might have some feedback.

    Bookmark   June 25, 2011 at 10:09AM
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I have a Veranda composite deck, about 700sq feet! It is less than 2 years old and has mold spots all over it! The deck is in the sun all day and we keep it clean! It is made by Fiberon. DO NOT BUY THIS PRODUCT!!!!!!! I spent $20,000 on my deck and it looks like crap! I tried the recommended Corte-Clean, and it did not work. It lightened the deck a little bit, but all the mold spots are still there. Filed a claim, and just received a reponse. Not covered- "We do not advertise our material to be maintenance free". I called and they are going to reimburse me for trying Mold Armor deck cleaner. If that doesn't work, I am contacting my lawyer. If I knew that there would be this type of problem, I absolutely would have gone with a wood deck. I could have paid someone to re-seal my deck every couple years!

    Bookmark   June 27, 2011 at 4:07PM
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Thanks everyone for the interesting reading. I have had my deck for 2 years. After one year there were the leapard spots/mold in the sun and shade (from house not trees). After scrumbing with the Expert Chemical three times plus trying Wet & Forget (which did nothing!) The only thing different is my Madeira Trex is lighter by half and the mold is more obvious. If Mold Armor or Corte Cleaner works can anyone tell me if there is a safe sealer? possibly one you can add color to since I painted my house trim to match the original color of the deck. I noticed that someone recommended Cedar Oil (Hartman Tree Farms) but that doesn't sound safe for the plastic component of the composite deck.
It sounds to me like bad batches of Trex are everywhere, I live in Virginia where the humidity is seasonably high but I use to live in San Diego where the humidity is very low except when it rains which is not often! I have to think that the wood Trex is using is not selected carefully and/or treated. To have mold problems in all different climates doesn't make sense.
Last year I had to replace 8 boards to get under the deck and those boards have not molded, however, I had to pre-bleach them before install so the color was closer to the rest of the deck. So I guess it is possible that I cleaned off spores before they had a chance to plant? or I got a good batch?
Please share your thoughts and suggestions for a sealer since Trex has not offered to help after I jumped through all their claim hoops. Debra

    Bookmark   June 29, 2011 at 2:56PM
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I used Mold Armor on a 10 year old Trex deck. It bleached the Trex so bad the deck is so ugly now. Went from a nice gray color (which matches the house siding) to a pukey yellow. Mold Armor made no statements about it changing the color of Trex or wood

    Bookmark   July 3, 2011 at 3:04PM
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I read this entire thread looking for "How to clean mold or mildew off of Trex decking". I currently only have 2 decking boards involved and those are outside the railings on the north and west edge of the deck. My deck is on the north side of the house but those involved areas are in direct sun for the majority of the day. I was mortified to read about all the composite problems people are having. I've read every comment and still don't know if there is anything that I can use to clean the decking that won't actually encourage more mildew growth. I think I have decided to try the Olympic Deck Cleaner pump spray simply because I didn't read any negative comments about that, but I say that with fear as well. My problem is fairly minor relative to some of the others who have written comments here and hope I'm not encouraging more growth by trying to "clean" it up.

    Bookmark   August 7, 2011 at 12:07PM
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Go ahead Patty and give the Olympic (premium) Deck Cleaner a try ($15 for a 2.5 gallon jug). It will make the mold go away - at least visually, for a few months. BUT it will return. I've had my Trex deck for about 3 1/2 years now and I've found I have to use the Olympic cleaner about 3 times over the course of spring through the fall. It appears to be a beach based cleaner with a couple of other ingredients. Spray it on - let it sit for 10 or 15 minutes and hose it off. It's that simple, but as I noted, whatever this mold stuff is, it will come back. I had installed a composite decking on my previous house, a few miles from here. I believe it was called Tech-dec. Don't think they are in business any more. Too bad. Never had any problems, over a period of 6 years, with mold or any other issues with that deck. So I have to agree with others, there seems to be something about this Trex material that facilitates the growth of this mold. Good luck.

    Bookmark   August 9, 2011 at 8:58PM
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I had a fake wood deck put on behind my condo a couple of years ago and it is turning greenish. I had a nice mahogony wooden deck at my other house and it pretty much took care of itself with a little brazilian oil on it every two years. This greenish look is for the birds but reading all the comments it looks like nothing will work on it. I guess the lesson is that natural is best.

But then again I'm glad everyone is using the artificial stuff because we are running out of wood.

    Bookmark   October 4, 2011 at 4:01PM
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I pulled this post from another site, it seems as though mold grows an sacred IPE??????
Mildew on ipe, nothing seems to be working


I've had my 1x6 ipe stickered up under a tarp in my backyard since May, and I am slowly working through the pile. Problem is I am now finding mildew spots on the boards, especially where they touched other boards. Not really surprising, it's been a ridiculously wet summer and even worse fall.

However I've searched here and other forums and nothing I do seems to make even the slightest dent in the mildew stains. Evidnetly straight bleach should dissolve it straight away - didn't touch it. Wolmans deck brightener (says removes mildew stains) - not a dent. Another commercial deck wash (also says removes mildew - smells like bleach) - nothing. Sodium percarbonate - also didn't touch it. I've tried each of these products both before sanding and after just to see if it mattered. It didn't.

So i guess its not just a man made junk problem as many others would have us believe, HEH
steve scholl

    Bookmark   October 5, 2011 at 10:14PM
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UltraMean 2 Professional does not work! I am very disappointed with the results. I followed the instructions on the bag to a tee, mixing two scoops per gallon of hot water. I applied the mixture to our mold stained 'ChoiceDek' patio and the black mold spots did NOT disappear after spending a few hours cleaning it. I did all of that work for nothing. I wrote an e-mail to Rhino Hide regarding my experience and they never responded. Would I recommend this product, hell no! ZERO STARS.

    Bookmark   June 21, 2013 at 1:50PM
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I have had my trex about 7-10 years I am guessing. I was so excited, maint. free and all. Boy was I wrong. Still looks nicer than any wood deck but need to clean mold/mildew twice yearly is a pain and I have a very large deck. Today for the first time I used a power washer on low pressure with the cleaner that came with it "G Clean", didn't do much as far as I'm concerned, for mold mildew etc, NOT. Its cleaner but all mildew/mold spores are still there so i thought I am going to try a test area with vinegar/baking soda and see what that does, pretty much nothing again. I can deal with the way it looks as the spotting doesn't show when dry so thats good but I am looking into prevention more than anything now. Any luck out there? I want to stay as organic as possible and may just do vinegar and baking soda and see how it goes. Not feeding the mold/mildew is probably better than anything. I live in MN which can be very wet at times and my deck is East facing primarily with some South sun as it passes on by to set in the West. I love everything about my trex except the mold issues

    Bookmark   April 20, 2014 at 7:34PM
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I have had my trex about 7-10 years I am guessing. I was so excited, maint. free and all. Boy was I wrong. Still looks nicer than any wood deck but need to clean mold/mildew twice yearly is a pain and I have a very large deck. Today for the first time I used a power washer on low pressure with the cleaner that came with it "G Clean", didn't do much as far as I'm concerned, for mold mildew etc, NOT. Its cleaner but all mildew/mold spores are still there so i thought I am going to try a test area with vinegar/baking soda and see what that does, pretty much nothing again. I can deal with the way it looks as the spotting doesn't show when dry so thats good but I am looking into prevention more than anything now. Any luck out there? I want to stay as organic as possible and may just do vinegar and baking soda and see how it goes. Not feeding the mold/mildew is probably better than anything. I live in MN which can be very wet at times and my deck is East facing primarily with some South sun as it passes on by to set in the West. I love everything about my trex except the mold issues

    Bookmark   April 20, 2014 at 7:37PM
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Cindifer stated that there still is mold issues with her Trex deck. As I said in my post (above 06/21/2013) I tried UltraMean and like you it didn't do diddly squat. I have found a product that does, it's Tilex Mold and Mildew Remover and it is available in a 128 oz. size from Home Depot. With a little elbow grease on a brush the 128 oz. size was enough to treat a 20' x 10' deck. The results are fantastic and the deck has gone all winter without any mold spots. I don't know if it be safe to use on your Trex deck, but you can try the same product in a smaller 32 oz. size in a small (hidden) area to be sure it doesn't affect the appearance.

Here is a link that might be useful: Tilex 128 oz. Mold and Mildew Remover

    Bookmark   April 22, 2014 at 2:27PM
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