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Community and Q&A

Is Azek a sustainable product?

WA | Posted in Green Products and Materials on

We are getting mixed signals regarding the green aspects of Azek. From a durability standpoint it seems to be a great material. However, does its high durability level outweigh the fact that it is PVC? I know the USGBC recently wrote a report on PVC … however it seemed to just add to the confusion, by not really taking a stance either for or against. I’d be interested to hear the thoughts of others here at GBA.

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  1. GBA Editor
    Martin Holladay | | #1

    Opinions on the suitability of PVC building products differ. Here's one opinion, from an article on the launch of new "virgin PVC" decking products; the article was published in the November 2007 issue of Environmental Buidlign News: "Although both Trex and TimberTech cite consumer benefits for their new PVC products, the Healthy Building Network’s Tom Lent has a different view. 'I consider these moves a disaster environmentally,' he said, adding that the health and environmental effects of the PVC life cycle should also be considered when looking at these decking products. Compared to the use of recycled plastics in composite decking, Lent said, the PVC decking 'is a big step backwards.' The introduction of PVC decking products by Trex and Timbertech, with the strength of PVC market leader Azek Deck, also raises questions about the health of the composite decking market. But both Day and Ferrari insist that the market is strong: "We’ve had a pretty good year,' said Day of Timbertech’s composite decking sales, 'and we expect to be going into a pretty good year.'"

  2. Expert Member
    Michael Maines | | #2

    There are a few places where it is the best material for the situation. I like it for plinths around porch columns, gutters, and bottom rails of porch skirting--places that real wood just won't last, at least without a level of maintenance people aren't willing to commit to these days.

    I trimmed a couple houses completely with pvc, but won't do that again. Not only is it nasty to work with; producing it is not good for the environment and as far as I know there is currently no recycling of pvc scraps.

    It seems much smarter to use smart design to eliminate the need for rotproof "wood." So what is the answer? We don't use fingerjointed trim, because the joints always telegraph. Primed pine has knots that bleed. I just don't trust anything resembling mdf outdoors. We are currently specifying C-Select locally grown white pine, that our painters or carpenters prime before installation, for any exterior trim.

    An easy test is, will the product last long enough to replace itself? That pretty much rules out anything made from pvc.

  3. Expert Member
    Michael Maines | | #3

    I wish there was a way to edit posts! I incorrectly stated that there is no recycling of pvc. It can be recycled, but it's hard to find recyclers, and the end product is not high quality. In contrast, aluminum is very energy-intensive to produce, but is easily recycled into a high-quality material.

  4. Riversong | | #4

    We need to learn the difference between greenwash and green. There is nothing at all green about PVC - the most common and most environmentally harmful plastic. Durability, alone, does not make a product green. If it did, then the 100 million tons of plastic swirling in the south Pacific vortex, forming a "continent" twice the size of the continental US would be a "green" island.

  5. Hugh Lippincott | | #5

    PVC is not currently a green sourced material, and the chloride is not good to have in fire (if the home burns); However, my wood frame, cedar shingled home has rotting trim boards, leaking water into the structure, and costing too much in maintenance, especially compared to the PVC sided houses. So I waste energy, ruin good paint & shingles or I use Azek trim. Or what else?

  6. Robert Riversong | | #6

    PVC can never be "a green sourced material" (whatever that means). It is a completely artificial chemical product that has significant environmental and health impacts throughout its life cycle and will never return to the environment in a benign way.

    To be truly "green" - that is, mimicking the sustainable and healthy flow of matter and energy through nature - a material must bio-degrade and/or become food for other forms of life. If we wish to allow life to continue on earth, we must change our perception of bio-degradation (rot) - it's a good thing as long as it's not premature (before the earth can replenish the source of the material).

    Plastic, in all its forms, is fast becoming one of the greastest threats to marine ecosystems, where life began and upon which all life depends (as well as the thermoregulation of the planet).

    Obviously, careful design and construction can significantly reduce the probability of premature failure of wooden materials. This includes proper siting and site protection; proper shielding and shedding through roof overhangs, gutters and sills; proper shingling of weather membranes and flashings; proper back and end-grain sealing; proper ground clearance and clearance to shrubbery; and proper grading and subsoil drainage.

    On-going maintenance should be considered part of our contribution to the earth community, just like recycling of non-renewables. Using high-pigment content stains rather than paint makes refinishing easier. You wouldn't buy a car and expect it to never rust without occasional washing, waxing and undercoating. What we don't need are permanent monuments to our collective short-sightedness.

    If you're getting water leaking into your structure, then replacing wooden trim with plastic is not necessarily going to prevent that. There is a problem with the weather membrane under the cladding or with flashing at junctures.

  7. jimblodgett | | #7

    At the end of it's intended life span, if you throw that Azek in the bushes, will it decompose and provide nourishment for organic regeneration?

    If not, it's not sustainable.

  8. GBA Editor
    Martin Holladay | | #8

    Your definition of "sustainability" is too simplistic. Neither clay roof tiles nor window glass will ever decompose -- plenty of Roman and Greek glass and pottery over 2,000 years old have been recovered.
    "Sustainability" is not synonymous "compostability."

  9. Pete Engle | | #9


    There's not much sustainable about clay roof tiles or window glass. I guess you could theoretically recycle both by grinding them up and reforming them into similar products, but there is currently no available recyclers who would do that. Both are very energy-intensive materials. Both come from large, though ultimately exhaustable resources. They are durable, though. So we're back to the PVC question: is durability enough to make something Green?

    And, doesn't sustainability require natural replenishment? If a product is made from a limited and nonrenewable resource and it is not itself 100% recyclable into an original quality material, I think that would make it unsustainable by definition. If you can't grow the feedstock, I don't see how any product could be considered sustainable.

    But this highlights the difficulty we have with terminology, even among the faithful. Does something have to be sustainable to be Green? Are there really shades of Green? Is selecting a more Green product over a less Green one good enough to qualify an overall building as Green? At what threshold of Green do we get Green Brownie points?

    FWIW, I'm in the camp that PVC products aren't nearly Green enough to count for much of anything

  10. GBA Editor
    Martin Holladay | | #10

    I have no idea how you define "sustainable," but according to the dictionary, a process or action is sustainable if it can be continued indefinitely.

    If you cross off window glass from your list of acceptable building materials because, in your mind, it's not sustainable, you have created a very limited list. Few people in cold climates want to live in homes without window glass.

    But seriously, Pete, I doubt very much that you have engaged in a detailed analysis of the glass-making industry, and determined how much window glass the planet can afford to sustainably produce. Really, these sustainability discussions get ridiculous very fast -- which is why I avoid using the word "sustainable."

    Good luck on your program to convince people to adopt windowless houses.

  11. Robert Riversong | | #11

    For how many millennia have people contentedly lived in the north country without glass windows? Igloos, hogans, wikiups and teepees have no windows. Shelter, for most of human evolution, was simply that. Today, Americans "need" a modest view outside because we live our entire lives (90% of our time) indoors.

    In the late Middle Ages, only the Church, the monarchy and the very wealthy had glass windows. In frontier America glass windows were still a luxury and the primary purpose of windows was to let air in and smoke out. In fact, the word "window" comes from the Scandinavian for "wind's eye".

    Whether windows are a "sustainable" product, I'll leave for others to figure, but as cutting-edge designers are now understanding, sustainable design allows us to engage in the same insanity as long as we can do so forever - such as living on the edge of crisis as long as we don't tip over.

    For that reason, I prefer "green", as in following nature's laws and designs, returning all material back into the cycle of life, not outgrowing our ecological niche or undermining natural processes, and subordinating our own desires to the higher order of Nature's body of which we are but a single cell.

    But what passes for "green" is far more a marketing scam to keep the present dysfunctional economy and culture going than a heartful commitment to serve the Web-of-Life.

    If we once again accepted "house" to mean "shelter" rather than a self-contained, highly-controlled environment containing life, work and amusement and isolating and alienating its inhabitants from the natural world in which they evolved and to which they belong, then most of these arguments would be moot.

  12. jimblodgett | | #12

    Martin - You said "Sustainability" is not synonymous "compostability."

    I was talking in the context of choosing between wood corner boards and composite trim.

    But now that you mention it, I agree, there are other ways a product can be used sustainably, like if it can be recycled back to it's original form without being downgraded. A challenge for many many materials we touch and use every day, including building materials.

    Since glass has been around for century's it's the ultimate way to get light and views into our buildings? It probably is right now. But I sure hope someone will come up with a more sustainable method eventually.

    Jeez. Can you imagine Thor, sitting at the mouth of his cave, munching a brontosauras burger saying to Juanita "if we could just block the wind from blowing in here...hey! I got it! (as he picks up a handful of sand and lets it sift through his fingers) We'll super heat this sand and make a clear air barrier! We'll call it glass!"

    Point is, we don't know what we're capable of until we strive.

    And yes, Martin, I do think the more compostible building materials are, the more sustainable the building. Are we going to reach complete compostability in my lifetime? Probably not. But all these freakin' composites, resins, toxins we use in the name of "durability" is taking us the wrong direction in my opinion. About 180 degrees in the wrong direction.

    Sorry about the spelling. Definite weakness of mine.

  13. Robert Riversong | | #13


    You're absolutely right. For 2 million years, every human shelter was either completely compostable or built of rock and soil that would eventually become part of the weathering cycle. Since the synthetic age, we have put ourselves outside of Nature's 3.5 billion-year-old cycle of waste-free material recycling and nothing that uses such materials can be considered sustainable.

    To be sustainable, the compostable or weatherable materials used to build shelter have to only outlast the time it takes for Nature to replenish what was used. Any "durability" beyond that is another form of hubris: creating monuments to our foolishness.

  14. Pete Engle | | #14

    Martin, I think we agree that the word "sustainable" can get us into trouble. This was probably the (not very well stated) point of my post. Since window glass is technically fully recyclable into the same quality product, I suppose one could call it sustainable, though it is still a high-embodied energy product, and that's going to be a problem.

    But I'm not at all sure that a product has to be "sustainable" to be "green" Certainly, sustainability is one criteria we can base our green definitions on, but there are just as surely others. And, if we insist on strict 100% sustainability in our green product definitions, we're going to have to build our buildings from a very short list of products.

    For window glass, its energy intensity seems to make it unsustainable, at least until we figure out free energy. But then again, it provides enormous benefits to the interior environment, including daylighting and capturing solar heat - both can serve to offset its original embodied energy. So, if we are judicious in its use, we may actually be able to offset enough energy use over the lifetime of a well-manufactured window system to offset its embodied energy. If we then compost the wood parts and recycle the glass, we've got a sustainable window. Now that sounds pretty green.

  15. Robert Riversong | | #15

    A side note about the marvels of glass windows.

    In hurricanes, the majority of injuries are caused by flying glass. At the Alfred P. Murrah bombing in OK City, 69% of injuries and 5% of fatalities were caused by flying glass.

  16. GBA Editor
    Martin Holladay | | #16

    I'm glad that further thinking has apparently changed your mind about window glass. You made an important point when you wrote, "For window glass, its energy intensity seems to make it unsustainable, at least until we figure out free energy. But then again, it provides enormous benefits to the interior environment, including daylighting and capturing solar heat - both can serve to offset its original embodied energy."

    Those sentences represent a far more nuanced statement than your original point: "There's not much sustainable about clay roof tiles or window glass."

    But you haven't really addressed the fact that the word "sustainable" is so often misused. "Sustainable" has nothing to do with "desirable." For example, it can easily be shown that it is sustainable to harvest a certain number of dolphins annually and grind them up to make dog food for American pets. Similarly, harvesting 1% of the trees in New York's Central Park annually for firewood is probably sustainable. But just because a practice is sustainable, doesn't mean it's appropriate, valuable, or worthwhile.

    Your original shoot-from-the-hip conclusion that window glass isn't sustainable because it can't be composted was baffling to me. I'm sure someone could find a way to manufacture window glass using solar thermal collectors -- perhaps large parabolic mirrors -- or PV arrays. I'm sure it would be expensive, but people like window glass. If fossil fuel burning is ever banned, I doubt that the manufacture of window glass would cease. It would simply become very expensive, as it was in colonial America.

    Anyway, almost no one is actually trying to do the math to determine sustainability. It very quickly becomes apparent that there is no such math, because such calculations include apples-to-oranges questions like, "What's worse, air pollution or water pollution?" or "What's worse, killing whales or human slavery?" Some questions don't lend themselves to quantification.

  17. Robert Riversong | | #17

    And some concepts don't lend themselves to a quantified, abstract, monetized or cost-benefit approach - such as "sustainability" - even with a whole-systems, life-cycle analysis.

    The only reason that it appears superficially "sustainable" to harvest dolphins, whales, redwoods or people, is that we have desacralized the world - the religious have moved God to heaven, and the secular/humanists have abandoned the sacred altogether.

    If you ask any indigenous person what is sustainable, you'll get a holistic answer which is not linear, mathematical, or logical - but is more truthful than anything that has come out of our own culture.

    Until "sustainable" means that which sustains our souls and the soul of the world, then it will remain not only a vague concept but a destructive one.

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