Why do people choose to use composite materials for their decks? Most everyone will say for one or all of these reasons that are not true:
Composites require little or no maintenance,
Composites are more environmentally friendly than wood, and
Composites are longer lasting than wood.
Mildew ail heavily build-up on a composite deck. Normal use of the deck wears off the protective plastic coating that surrounds the wood particles in the composite, leaving them exposed to mold and mildew. Wood in its natural state contains chemicals that fight off fungus. But, the wood flour used in composites has had most or all of these protective chemicals removed, so it is very vulnerable to mold and mildew when the wood particles are exposed.This is a Trex composite, but most non-capstock composite decking materials have this problem to some degree.
Is any of this actually true? Do composites really require less maintenance? Are they more eco-friendly? And, do they really last longer then wood decks?
After twenty-five years of experience with these products, we can confidently say that none of these beliefs is actually true.
So, how did these myths come to be? Are the composite manufacturers just lying to us?
Not really. (Well, maybe just a little.) They were fostered by composite manufacturers in the heady early years of the product when claims of “maintenance free” and “lifetime decks” were tossed about freely. The manufacturers relied on predictions about how the material should behave, but failed to do the long-term research to substantiate the truth of the claims. Now that a little time has passed and some research has been done, these expansive claims are just not holding up. In fact, since 2004, seven major wood-plastic composite manufacturers have faced class-action lawsuits related to a host of material problems, including fading and color changes, slippery surfaces, shrinkage, swelling, deterioration and massive mold buildup.
Keep in mind that all composite decking materials, including capstock composites, are still largely experimental. Unlike wood (which we have worked with for about a million years and the characteristics of which we know very well), composites are a new and imperfectly understood material.
Scientists can approximate how a particular chemical stew of plastic, filler and additives will react to prolonged exposure to the elements over time, but without actual long-term exposure tests they never know for sure. And, no manufacturer tests its material for 25 years before putting it on the market.
The result has been a lot of failures, a half-dozen class-action lawsuits, and several major composite decking companies going bankrupt or quitting the business, some after massive recalls of defective and dangerous composite decking products and wholesale defaults on their warranties.
Yet, even after claims of “maintenance free” and “lifetime deck” have been thoroughly debunked by research and experience, we still see them widely repeated, even by those who should know better. As late as July, 2012 the online edition of Popular Mechanics reported that:
“The appeal of composite decking is that it’s virtually maintenance-free. It never needs to be sanded, scraped, refinished, or stained…”
No deck is actually maintenance free. Routine cleaning and maintenance is required for both wood and composite decks. Composite manufacturers now admit that there are no “maintenance free” decking materials of any kind. Every decking material needs at least a periodic washing. Mold, mildew and dirt attack every deck - plastic, metal, wood or composite — with evenhanded tenacity, and have to be taken care of at regular intervals. All composite manufacturers now not only admit that maintenance is necessary, but usually recommend a periodic maintenance schedule, specific procedures and even products by brand name for cleaning and maintaining their composite materials.
(Source: http://starcraftcustombuilders.com/)