Dear Dot: I Need a Deck Discussion



Dear Dot,

I want to put a deck on my home to have a place to enjoy the views and wildlife. I’ve read that composite decking is environmentally friendly because it is made from recycled materials and doesn’t require chopping down trees. However, I’m skeptical of any materials containing plastics or chemicals. Are composites really as eco-friendly as they seem?

–Sam, Massachusetts

Dear Sam,

Oh, how I long for the simple questions. Alas, it seems my fate (or, at the least, my job) to wade through the not-so-simple, to parse the rhetoric soaked in eco-friendly promises, to bear the weight of your and my consumer choices.

But perhaps we complicate things unnecessarily. I’m reminded, for instance, of a line from Cradle to Cradle: Remaking the Way We Make Things, a groundbreaking book published in 2002, that boldly urges us, when considering design and materials, to “stop trying to be less bad and … start figuring out how to be good.”

So, Sam, let us determine how that applies to your desired wildlife-viewing platform. 

Let’s start with the obvious choice for decking: wood. And within that obvious choice is a number of other choices: pressure treated, bamboo, mahogany, cedar, black locust … the list is long. 

How do trees stack up as a sustainable building material? Trees remove carbon from the atmosphere and it remains sequestered until the tree is burned or biodegrades, at which point it is released. So although cutting down a tree renders that tree incapable of capturing more carbon, it nonetheless holds (for the most part) the carbon already captured. What’s more, you can choose reclaimed wood (which means no new trees are cut down to facilitate your wildlife viewing) or you can purchase wood that is Forest Stewardship Council (FSC) certified, a widely respected third-party certification that operates with regard to environmental principles, worker rights, and Indigenous rights. Thus, reclaimed/reused or FSC-certified wood falls firmly into the “good” category. Steer clear of wood that is not harvested responsibly — don’t hesitate to ask your flooring supplier how wood is selected — or wood that comes from endangered or threatened species. Wood, however, is subject to decay and is attractive to termites and other bugs that cause damage. It also splinters and cracks with age. Sealants or stains can lengthen its life as a deck, but they are typically fossil fuel-based. 

Still, wood is a natural carbon-sequestering material that, purchased carefully, can be a responsible choice.

But, Sam, you specifically mention Trex, part of a family of what are called composites. While companies such as Trex and TimberTech proudly tout their eco bona fides, it’s not quite that simple. Nonetheless, there’s room for optimism.

Here’s what I mean: On the front end, Trex positively glows with eco-luster. According to Zachary Lauer, vice president of supply chain at Trex, “95% of [Trex] boards are recycled or reclaimed materials.” Trex uses primarily polyethylene from plastic bags (remember the reader who asked Dot about Stop and Shop’s plastic bag program? That’s one of the spots where Trex sourced its materials), but also stretch wrap and packing materials. In fact, Trex is the largest user of those recycled materials and, what’s more, those are plastics that are somewhat undesirable from a re-use point of view because the quality of the plastic is so poor that it’s hard to turn them into something useful. But Trex also adds in post-industrial wood dust and pallets and other no-longer-useful wood materials. They do this because it contributes to the strength, durability, and appearance of the Trex boards while providing a use for, again, no-longer-useful materials.

But here’s where Trex is potentially problematic. Although Trex boards are 100% recyclable by Trex in its facility, this mixture — wood and plastic — means that Trex boards aren’t recyclable via typical, easily available streams. 

What Trex would like is for builders, contractors, or even homeowners to get any Trex decking that they no longer want or need back to its facility. Because Trex is a relatively new building product — the company was created in 1996 and its products are warrantied for 25 years — this end-of-lifecycle consideration is just becoming something the company is dedicating time and resources to. “We’re constantly working with our channel partners to establish that end-of-life type thing,” says Lauer. But, he admits, it’s not in place at the moment. The company, he says, is founded on finding purpose for products that are essentially throwaway and Dot feels confident that, by the time someone else considers tearing out your wildlife viewing platform, a program will be in place to recycle those Trex boards, should you choose to go that route.

But Trex isn’t the only popular composite, of course. TimberTech decking boards, from AZEK, are produced with approximately 50% recycled materials, such as PVC pipes and old vinyl siding, says Amanda Cimaglia, VP, ESG and Corporate Affairs at The AZEK Company. PVC or polyvinyl chloride is, like plastic bags, a hard-to-recycle product that more typically ends up in landfill. Similar to Trex, TimberTech has what they call a “Full-Circle Recycling Program,” which takes back PVC scrap and cutoffs directly from job sites from dealers, contractors, and lumberyards to be recycled. TimberTech, again like Trex, is a relatively new product but is aware that pressure is mounting to expand its recycling initiative to also take back decking that is no longer wanted, such as during a teardown. But, Cimaglia says, “From a logistics perspective, because it’s such a specialized material  — and we’d want to ensure it gets back to AZEK — it would still require that the customer works with their contractor or local lumberyard to get a Full-Circle Recycling bin onsite for collection.”

Finally, Sam, you asked whether there are any health concerns with walking on (and viewing wildlife from!) a recycled plastic or PVC platform. 

There’s no more health concern walking on this material than there is handling recycled polyethylene or PVC, which is something most of us do every day. While PVC is the more toxic of the two plastics, and Dot typically discourages use of PVC products, there is scant evidence that there’s a negative impact to your health from walking on it. 

Whichever decking material you choose, consider the steps you can take to further ensure that its impact to you, the wildlife you long to admire, and the environment is as benign as possible.

Happy wildlife viewing, Sam. 



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  1. As a homeowner who was excited to install Trex decking because of my wish to be environmentally conscious, I’m here to tell you… don’t do it. After one year with our Trex deck, it started to grow black mold spots. Since this was sold to me as a “maintenance free” material, I was disheartened. I tried power washing, using an eco-friendly mold cleaner. It did not work. We resorted to a chemical cleaner that I know was toxic. But we couldn’t be walking barefoot on a moldy deck. It was harder to clean than our old wood deck. So much for maintenance-free. The mold came back the next year and we just could not keep using that toxic cleaner. We ended up tearing out the Trex. What we discovered was that the entire underside of the boards were saturated and “punky”. The material was like a sponge holding in water. But did we learn our lesson? No we did not. We tried Trex again after being told by the manufacturer that they had improved the product. The results were the same. We ended up tearing out 2 Trex decks and going back to wood. We have friends with an Azek deck and they love it. I, however, don’t like the plastic look of the material.


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