10:34AM | 09/14/05
Member Since: 09/13/05
10 lifetime posts
Our contractor recommended and installed Timbertech composite lumber when we built a large deck three years ago. After the first few rains, we began to have severe widespread black mildew spots. Our deck is in full sun and we keep debris off faithfully. We have used three different cleaning products mixed with bleach, pressure washed, about four or five times per season. After what we have experienced and spent on various cleaning and sealing products, I would not recommend using Timbertech. It was advertised to be "specially designed to provide years of virtually maintenance-free use and enjoyment." The company stands by its warranty by offering to replace the product, however, the vast majority of our cost was in labor, installing a hot tub, and building and painting rails around the deck. The labor and materials for replacing the decking would cost ten times more than the decking itself. And it would still be the same product. We have continued to address the mildew issue with frequent cleanings and recently sealed it. So far, the best product we have found is PSC Deck Restorer, Afterclean, and Protector, a three step process that cleans and seals. It was expensive, labor intensive, but after a month, the mildew has not yet returned. We are hoping to extend the time between treatments. Does anyone

have any sucess with other cleaners/sealers on composite? We are hoping to find a less expensive product that is effective.


07:26PM | 09/18/05
Member Since: 12/27/02
543 lifetime posts
Any wood or wood composite will require some maintenance especially in a wet climate on the north side... check the source:

I found this at


Basic Cleaning Recommendations

TimberTech highly recommends periodic cleaning of your TimberTech deck to help maintain the beauty of the product. Most deck-cleaning products will work on TimberTech. For best results use a cleaner that contains any of the following as an active ingredient for general cleaning and follow the manufacturer’s instruction for use:

• Phosphoric Acid

• Oxalic Acid

• Hydrochloric Acid

• Sodium Hypochlorite

Power washing will enhance results when cleaning your TimberTech deck. 1500psi is the recommended maximum for TimberTech products. A fan tip nozzle should be used along with the proper cleaning product. Spray in the direction of the brush/grain pattern to avoid damaging your decking. Use caution not to damage the material and always take the proper safety precautions when operating a power washer.


Here is a video:

Here is what they have to say on MILDEW:



Wash your deck periodically with a cleaner like Zinsser's JOMAX ( that contains or is mixed with Sodium Hypochlorite. Follow the manufacturer’s application instructions. Use a stiff brush to scrub heavily stained surfaces following the grain.

Rinse off your TimberTech deck periodically with a hose. Even if your deck appears clean, it is important to prevent build-up of pollen/debris. Mildew stains may occur where moisture, pollens, and/or dirt are present. Mildew needs a food source to grow, which can be grass, pollens, dirt, debris, wood and wood resins.

Maintaining a clean, dry deck surface is the best method for combating mildew. Ensure that water drains effectively from your deck. Keeping weep holes clear and unclogged on TimberTech Floorizon Planks. For TimberTech TwinFinish 5/4 and 2x6 planks, be sure that gaps exist between planks to allow for drainage.

Spot Stains

Oil Eater Cleaner and Degreaser is very effective against oil, grease and other stains. For extra heavy oil and grease stains or other specific stain types, check with your local lumberyard, hardware stores or home centers for cleaners applicable to a specific stain type.

If stains have set, you may want to use fine sandpaper and sand lightly, following the wood grain finish of the plank. The sanded area will weather back in approximately 8-10 weeks.


Alter Eagle Construction & Design | Construction & Design | | Decks, California outdoor living | | Molding and finishing | | Crown tutorial


09:04AM | 09/20/05
Member Since: 09/13/05
10 lifetime posts
I have followed the recommendations from the timbertech literature and the customer service representative. It really bugs me that they repeat over and over that pollen and environmental stuff is a breeding ground for mildew. My pressure treated lumber small decks that have stain have no problem with mildew, only the big Timbertech deck. These decks are in the same environment, except my wood decks are in full shade. Jomax mixed with bleach has been great for painted rails and other surfaces, but it was the least effective on timbertech mildew. I have also used the Timbertech cleaning product mixed with bleach, and it was more effective, but not as effective as PSC cleaner mixed with bleach. It is really obvious to us, our contractor, and other people who have cleaned our deck that the mildew is much deeper than surface, and seems to eminate from within the material and rises to the top. If it was surface mildew, it would be coming off without having to clean and soak it repeatedly. The mildew also does not scrape off. It is deeper.

The sealing after cleaning with PSC seems to be working, although it has only been one month and we are hoping it stays mildew free. But that brings me back to the original complaint. After spending all this money on Timbertech, why must I still clean and seal more than I do on my pressure treated lumber?


06:29PM | 03/16/07
Member Since: 03/15/07
1 lifetime posts
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 Timbertech 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 Timbertech 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 Timbertech 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.


04:28PM | 04/15/07
Member Since: 04/14/07
2 lifetime posts
You may want to review the label directions of bleach containers before mixing anything with it and using it for purposes not stated.

This violates federal and state laws, pollutes and is dangerous.


10:08PM | 04/15/07
Member Since: 12/27/02
543 lifetime posts
An excellent point, even though the company recommendations include the use of • Phosphoric Acid • Oxalic Acid • Hydrochloric Acid or • Sodium Hypochlorite always use caution with any chemical.

Personally I would try to find anything that would be environmentally friendly first. Even then you have to read the fine print...

For example I found moldex deck ( ) by Envirocare but further reading found it also recommends the use of bleach.

The same with fiberon ( ) decking...

PSC also requires bleach ( )

I would start a search of the see what recommendations they have and go from there.

Alter Eagle Construction & Design | Construction & Design | | Decks, California outdoor living | | Molding and finishing | | Crown tutorial


04:10PM | 07/06/07
Member Since: 07/05/07
1 lifetime posts
I have found a product that is eco friendly and does not have any chlorine bleach in it or added to it. It is called Corte Clean. It cleaned my Timbertech deck better than anything else I tried. Love the product! Took the black mold spots out of my deck and they have not returned in months.

When I used deck cleaners that contained sodium hypochlorite they returned with in weeks.


01:23PM | 07/14/07
Member Since: 07/13/07
1 lifetime posts
I am about to purchase the Timbertech Floorizon T&G product for my new deck. Was your mold problem on the Floorizon line or on one of the other Timbertech products?


08:56AM | 09/07/07
Member Since: 09/06/07
3 lifetime posts
I have been working with TT material a long time. The Floorizon (T&G) material will stand up and be beautiful if you make sure you install it correctly. Read the Installation Manual on proper installation requirements. If you plan on building your deck close to the ground or enclose it, check first. Floorizon requires at least 12" of un-obstructed airflow on at least three sides of the deck. If you have that great! You will love it! Easy to install and maintain. As far as mold and mildew, Corte-Clean is the best cleaner out there thus far! It is also Environmentally safe! Check out their website. Awesome before and after photos.


07:40AM | 03/27/08
Member Since: 09/13/05
10 lifetime posts
Its been a long time since I've posted. I still have perpetual maintenance with the Timbertech deck, and still regret building with it due to mold problems. I do not have trouble with rot or splinters, though, as some other composite owners have complained. If I can find the "magic" cleaner and protector at an economical price, I would not be so angry about this, still.

My routine the past two years is to keep it free of debris once a week with the leaf blower. In the early spring and in the fall, when it is too cold to use PSC cleaner/protector, I clean it with Dawn dish soap and clorox, diluted. It looks OK for a few weeks.

Around June or July when I see there will be several dry days in a row, I use the very expensive stuff. PCS deck cleaner and restorer. It takes one day of cleaning, another day to dry, and then I apply the Restorer to make the deck more waterproof. This seems to prolong the time between reappearance of mold black spots. Then in November, before the snow flies, I clean the deck again with Dawn and Clorox. After a long winter, it always looks very dirty, and I like to get it clean as soon as we can. Neither Corte-Clean, nor PCS can be used when it is still under 60 degrees.

I am tired of spending all this money and effort on a "low maintenance" deck. I bought some Corte-Clean online, could not find it at local retailers. I am going to try this product this spring as it has had good reviews. I'm thinking that it would still be wise to recoat it with protector after Corte- Cleaning it to keep water out.

If you are thinking about installing a composite deck, I would discourage it. If I had to do it over again, I would have gotten a few boards, put them outside for a season, to test them for quality. If I had done this, I would have seen the utter failure of Timbertech to maintain a decent appearance. If anyone hears of a class action suit against this company, it would be a responsible thing to join.

I don't have any experience with the newer lines of Timbertech, and wonder if they have been improving it due to complaints. Our building contractor refuses to use it any longer
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