Composite decking materials are made from a combination of wood fibers and plastic. Several manufacturers have been involved in class-action lawsuits, largely because consumers claim the wood lookalike harbors mold.
Trex, a popular manufacturer of composite decking, says mold will not damage the deck boards. Still, the manufacturer recommends cleaning the deck periodically, and offers these guidelines for removing mold from its composite decking:
If you see mold on your deck, clean it with a commercial deck wash containing a detergent and bleach (the ingredient on the package might call it “sodium hypochlorite"). The bleach, Trex says, will remove the mold, but also could lighten the color of the boards.
Trex recommends these products for cleaning mold from composite decking:
Apply these products to a dry deck. If you use them on a wet deck, they won’t work as well. Never mix bleach with other cleaners.
Repeat the process until you can no longer see any mold. Because mold is not always visible, clean the deck with this product periodically to kill any spores that you can’t see.
As an alternative to chlorine bleach, Trex recommends a product called UltraMean. You will have to scrub the product into the deck immediately after applying it.
Composite decking is not a food source for mold. Still, the dirt and debris that collect on a deck does feed the spores. So be sure to keep your deck clean and free of debris to prevent mold.
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