GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Open Cell Spray Foam Waste used as attic insulation

phalkias70 | Posted in Building Code Questions on

I recently had my home exterior walls insulated with an open cell spray foam. The contractor does not take away the waste generated by the installation and subsequent trimming of excess spray foam, so now I have bags and bags of excess cut foam pieces. I was thinking that I could break it up into finer pieces and add it to the top of the batt insulation in my attic ceiling area. Is there any code violations involved in doing this. The only thing I can think of is an issue of flammability. The attic is fully vented and any light fixtures located in the ceiling joist bays are rated IC and airtight. I am trying to kill two birds with one stone. Get rid of the waste and add some insulation R-value to my attic ceiling.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. GBA Editor
    Martin Holladay | | #1

    I'd advise against the practice, for two reasons:
    1. Exposed foam is, indeed, a fire hazard.
    2. Unlike undisturbed foam that is sprayed in place, broken pieces of cured foam provide no resistance to air flow. I doubt whether they provide much R-value, since air can easily pass through the broken pieces of foam.

  2. phalkias70 | | #2

    I kind of thought the flammability issue would put the kybosh on the whole idea. Now the question is where to get rid of it?

  3. GBA Editor
    Martin Holladay | | #3

    I think than any spray foam contractor who doesn't take responsibility for job waste is irresponsible.

    One way of shaming this contractor is to name the company and city.

  4. homedesign | | #4

    I think the practice of charging to haul away "foam-waste" is common in North Texas
    At least with the contractors that I talked to.

    The amount of waste with an open cell job can be LARGE

    Not only is there a FEE .. there is a high volume of foam filling up the landfill.

  5. GBA Editor
    Martin Holladay | | #5

    Any company that claims to be environmentally responsible should have a waste disposal plan. If a contractor's routine work generates waste, then disposing of that waste in a responsible manner should be part of the contractor's routine services -- in my opinion.

  6. homedesign | | #6

    I am moving away from foam for many, MANY reasons.

    I am curious
    How COULD the contractor dispose of the foam in a responsible manner?

  7. GBA Editor
    Martin Holladay | | #7

    Excellent question!

  8. jbmoyer | | #8

    If your spray foam contractor is generating a lot of waste from trimming overspray, find a different contractor!!!!

    Quality contractors will have minimal overspray.

  9. homedesign | | #9

    are you thinking of closed cell or open cell?
    I have witnessed several different companies apply open cell
    When they overspray in order to fill the cavity the waste allways seems Large.

  10. Riversong | | #10

    How COULD the contractor dispose of the foam in a responsible manner?

    Use it to cap a landfill. This will retain the heat of decomposition and accelerate methane generation, which can be captured to use for generating electricity in a combined heat and power plant.

    Or maybe not.

    Every construction or remodeling contract should end: "The site will be left broom clean."

  11. phalkias70 | | #11

    In all fairness to the contractor, he did stipulate in his contract that he would bag it and clean up, but disposal in the end was up to me. This being my first spray foam experience I did not realize the waste that would be generated.

  12. Bill Clark | | #12

    Check the spray foam's ICC report, many are approved for use in attics without any fire coatings and will not cause any fire or other issues if placed in the attic.

    Excess cut-off spray foam insulation will generally NOT allow air to pass through it, and even if it does, all traditionally used insulation products except spray foam allow air to move through them.

    Open cell spray foam is mostly comprised of air and is completely safe to take to a landfill. IT will crush down to almost nothing when driven over with tractors commonly used to compact the waste stored there. Contrary to common belief, there is very little decomposition going on in the landfill except for food waste as a few minutes with Google will attest.

    There are much better methods of installing spray foam insulation in walls where very little waste is generated and most responsible Contractors are switching to this method, its better for the environment and their bottom line as all waste is also wasted profit...

  13. Brett Moyer | | #13


    I am referring to open-cell. There should be minimal overspray if the contractor is skilled.

    I've actually seen one contractor use Insulweb with open-cell spray foam-- no overspray.

    Great method if I specified full cavity open-cell spray foam in my wall assemblies. BUT, I don't.

    I actually believe that any foam in above grade applications (with the exception of air sealing penetrations and rim joist areas) does not belong in a green building discussion.

    This is certainly true when we are talking about new construction. With existing homes, insulating can be difficult, and foam boards/spray foams in some scenarios are the best solution.

  14. Riversong | | #14

    I actually believe that any foam in above grade applications (with the exception of air sealing penetrations and rim joist areas) does not belong in a green building discussion.

    So good to hear others corroborating what I've been saying for years. Petrochemical plastic foams are the antithesis of green.

    Bill Clark ( No decomposition is exactly the problem. Plastics last virtually forever in landfills and elsewhere in the environment, including the great Atlantic and Pacific garbage patches, where they do break down in size, becoming smaller and more dangerous to the biosphere. Green materials compost back into their natural constituents and become food for new life.

    And you're completely wrong about pieces of cured foam acting as an air barrier. It is an air barrier only when foamed in place or placed as a tightly-fitted and sealed rigid board.

    But dense-pack cellulose is so good at limiting natural convection that it is third-party approved as a fire-stop in lieu of solid wood. Even a few inches of loose-fill cellulose topping has been proven to control convection through existing fiberglass.

    Why is it that spray foam installers are almost without exception completely ignorant about building science, even regarding their own product?

  15. Peter | | #15

    Check the spray foam's ICC report, many are approved for use in attics without any fire coatings and will not cause any fire or other issues if placed in the attic.
    The open cell foam used was from Lapolla and called foamlok.

  16. MICHAEL CHANDLER | | #16

    The fire retardants in spray foam and board foam are a bio-accumulative neuro-toxin so disposing of waste foam in a landfill is not doing the planet any favors.

    We do have a bio-degradable alternative, Triethyl Phosphate (TEP), which has been tested with open cell spray foam and is bio-degradable when disposed in a landfill. We also have a less toxic alternative (TCPP) Tris(1-chloro-2-propyl) phosphate which is still bio-accumulative and non-bio-degradable but much less toxic than the other chemicals commonly used.

    I am very much aligned with John Brooks in doing what I can to find ways to minimize the use of spray foam, EPS, and XPS. in the homes I build. I'm not there yet, but moving in that direction.

    With the new LEED and NGBS standards in development right now we have a great opportunity to create market incentives to using environmentally preferable flame retardants in carpets and foam products. I have submitted amendments to NGBS (901.5(3) and 901.11(c)) to give points for using environmentally preferable flame retardants in flooring and foam products and will be proposing amendments for encouraging those who build without halogenated flame retardants.

    In general it is more effective to give credit for using a preferable alternative than for not using a bad alternative because it is difficult to write a standard general enough to include all the bad things possible but easy to find a good thing and give credit for implementing it. We have until January 31 to recommend amendments to the NGBS but the LEED for Homes comment period closes today.

  17. Riversong | | #17

    I am very much aligned with John Brooks in doing what I can to find ways to minimize the use of spray foam, EPS, and XPS. in the homes I build. I'm not there yet, but moving in that direction.


    Nice to hear that you're moving toward green. I must be having an influence on you ;-)

  18. jklingel | | #18

    Why couldn't the cat throw the pieces into the hopper with the cellulose that he is going to blow in over those fiberglass batts? I would guess that the foam being shredded and mixed with the cellulose would at least postpone its getting to the land fill, and in the meantime it could be doing some good. No?

  19. Riversong | | #19

    I think most cellulose blowers would just plug up with pieces of foam in the hopper. It would also create lots of static electricity in the blower hose. The agitator would not shred the foam, as it's only made to break up a fiber that's already shredded.

  20. MICHAEL CHANDLER | | #20

    Robert I'm sure you have had quite an influence on me, especially as to being careful as to how I word things to keep it polite around here but I have to give credit to Arlene Bloom for this one.

    My wife and I got to spend some time with her at last years Build Well conference and she and Theo Colburn really got me thinking about the unintended consequences of some of the chemicals we use in our pursuit of improved energy efficiency. The flame retardants are honestly much more of an issue in carpets and furniture than in insulation but we probably have the best chance to introduce a premium "environmentally preferable" category for flame retardants in the spray foam industry through the NGBS and LEED standards review process which would make these products available to furniture and board foam makers.

    American Furniture makers and IKEA have shown interest in this type of a product and the spray foam guys are duking it out over "bio-content" there is an opportunity to make a real difference here which is what this is all about to me at least. In my spare time that is, when I'm not theiving and greenwashing. ;-)

    You can read more about Arlene's work at her BuildWell Forum blog here:

    Theo Colburn has a pretty alarming discussion and video about the issue here:

  21. Riversong | | #21

    It's interesting what moves different people toward more sustainable choices. For some it's personal health or the health of clients, for others it's environmental impacts, for yet others it's simply a philosophical approach to living.

    And it's also fascinating that we continue to be surprised at the toxicity of so many chemical products we assumed were benign, such as DDT or asbestos (or cigarette smoke).

    Of course we would not find ourselves so often surprised by the unintended consequences of our choices if we used the Precautionary Principle, which requires that any new thing be proven safe (and necessary) before introduction into the marketplace and environment, rather than waiting until someone discovers it to be unsafe.

    On that basis, it would be reasonable to assume that all 80,000 petrochemicals we've created, that never before existed on earth, are unsafe until proven otherwise.

  22. MICHAEL CHANDLER | | #22

    Robert I do agree with you on how interesting the varied motivations are that drive different people. I actually have the book "Drive" by Daniel Pink in my audible reader for my drive to the International Builders Show next week. (along with Keith Richard's new book)

    It's also interesting that many of these endocrine disruptor flame retardants were developed in an attempt to replace predecessors that were carcinogenic. And it's really interesting to sit with research scientists and discuss different testing protocols. Many of these compounds have been tested and proven safe as defined by Non-carcinogenic, only to later discover that they weren't tested by a method that could find that they were neurotoxins.

    "Proven safe" ends up being less meaningful every day.

  23. Riversong | | #23

    "Proven safe" ends up being less meaningful every day.

    And that's the real message - because nothing can ever be determined safe a priori, it is prudent to avoid anything new which is not clearly necessary and beneficial.

    The precautionary principle states that if an action or policy has a suspected risk of causing harm to the public or to the environment, in the absence of scientific consensus that the action or policy is harmful, the burden of proof that it is not harmful falls on those taking the action.

    The precautionary principle is most often applied in the context of the impact of human actions on the environment and human health, as both involve complex systems where the consequences of actions may be unpredictable and may be irreversible.

    In the European Union the Precautionary Principle is the law:
    "A willingness to take action in advance of scientific proof [or] evidence of the need for the proposed action on the grounds that further delay will prove ultimately most costly to society and nature, and, in the longer term, selfish and unfair to future generations."

    Generally, the Precautionary Principle is applied whenever there is a recognized probability of risk, but in 1982, the United Nations World Charter for Nature gave the first international recognition to the strong version of the principle, suggesting that when "potential adverse effects are not fully understood, the activities should not proceed."

    This used to be called prudence or forebearance.

  24. Katie | | #24

    As a spray foam contractor, we are not in the habit of buying into the "Foam is Green" marketing ploy and do not sell it as such. We install open- and closed-cell spray foam for its high insulation value and air barrier qualities (when applicable) to people who can afford the upgrade. Period. We are honest with people who are considering foam: it's expensive, it's combustible, it's plastic, and the initial off-gassing (although more dangerous to installers than building owners) during install may be a nuisance to sensitive people. Spray foam is no more green than paint or carpet or furniture (or cellulose and fiberglass for that matter). BUT -- if you want a permanent insulation that will not contribute to mild/mildew and offers a high R-value and is an awesome air barrier, spray foam might be for you. If building owners make it through that spiel unphased, then we consider them a good candidate for spray foam.

    The spray foam industry is still in its infancy, and there's a long way to go until it becomes a respected and viable industry, like cellouse and fiberglass have. Yes there are spray foamers out there who have no idea what they're doing -- they simply saw a trend and wanted to cash in. Yes, there's a lot of waste with open-cell, no matter how good an installer you are. (Waste is different than overspray, by the way) Yes, the product can't be reused and takes up alot of space in landfills. But what insulation is truly green? None that we can think of.

    By the way, we wouldn't recommend shredding up open-cell waste and puting it in your attic (or anywhere, really), for all the reasons discussed: fire hazard, no air barrier, no insulation value. Plus, dust particulate would be an issue. We once tried putting open-cell waste in our fiberglass blowing hopper to shred it up and blow it in an open space just to see what would happen and if it could be done. The hopper reduced the insulation to fine pellets and there was a ton of dust. Hardly worth the time or effort to "recycle" the foam when the only thing you'll gain is a fire waiting to happen.

  25. GBA Editor
    Martin Holladay | | #25

    Thanks for your refreshingly honest post. Your direct attitude should win you the confidence of your clients.

    Sales pitches that are free of exaggeration are always the most effective, in my book.

  26. homedesign | | #26

    You did not mention your last name?
    You also did not mention the maximum legal thickness of foam,
    intumescent coatings or code required fire protection.

    Is it the foam contractor's responsibilty to inform customers of these issues?

    What percentage of your attic foam jobs include intumescent coatings?
    What percentage include drywall protection?

  27. phalkias70 | | #27

    Thanks Katie. I guess I will have to find something else to do with the generated waste.

  28. wjrobinson | | #28

    John Brooks This site is not yours. It is not mine. It is owned by Taunton. You have asked for full names etc. hundreds of times. What is it with this obsession? Kate's post was good and just what my spray foam contractor says. Martin liked it, and didn't ask for her SS#.

    If she posted as Kate Brown you would have been ________ ?

    Most that post multiple times toss us some moniker and that can work if we all follow the rules posted.

    Taunton does not ask for last names John. If you need last names there might be a site that fits your need. This site doesn't.

  29. Riversong | | #29

    Katie: "But what insulation is truly green? None that we can think of."

    Apparently not thinking very hard. Of the commonly available insulation materials, borate-treated cellulose is an order of magnitude more green than any other. Because the paper is 100% recycled, it does not contribute to deforestation, but instead removes one of the largest volume contributions to land fills.

    It's 100% natural (including the borates and the typical soy-based inks), non-toxic to humans and pets, highly fire-resistant and resistant to convection (qualifies as a fire stop), insect-proof, rodent-resistant, sound-deadening, and mold-resistant. And, because of its highly hygroscopic properties, is the only common insulation material that buffers indoor relative humidity, protects wood framing from moisture accumulation, and allows a thermal envelope to breathe (transpire moisture) which is a foundational requirement of the Bau Biologie approach to healthy homes.

    The only insulation that is more green, though less effective, is light straw clay or wood chip clay or - for new construction - straw bale. Recycled blue jean batts come close, too, but suffer from the installation problems that all batts share.

  30. Riversong | | #30

    Most that post multiple times toss us some moniker and that can work if we all follow the rules posted.


    AJ, your defensiveness is expected from those who hide behind pseudonyms. If you are afraid of sharing your real name, at least have the decency (and smarts) to not make anonymous cowardice into a crusade.

    Those of us who prefer to know with whom we are conversing have a right to expect others to be as transparent as are we. Honesty, openness and reciprocity are the foundation of all wholesome relationships. Secrecy destroys relationships.

  31. wjrobinson | | #31

    Robert, I hear you. I value honesty. I value my moniker too though we differ on that. There is only one of you or I and I'm sure the world is happy at the limit.

    Specifically as to Katie, who needs her to post a full name????

    Taunton owns the site. Martin is part of the Taunton team.

    I see John as over asking for names names names.

    And in Kate''s case, I think she was as honest as anyone could ever ever post. So she was able to post to our needs of honesty and may not thought the same as John or you.

    I will have to agree to disagree gents.

    You don't need Kate's last name to improve her post.

  32. user-757117 | | #32

    AJ, I thought you were cutting back on your engagements?
    Why not take it to "The Tavern" if you have further comments?

  33. wjrobinson | | #33

    Names... was just thinking of how many people I know but don't know their last name offhand. The list is endless , must be as many as I do and it does not raise concerns with me like you two post about endlessly.

    When have either of you ever posted, you would agree to disagree with someone who feels differently than you?

    I mean well guys. And I post my name my way, and you yours. I have no problem with that difference. I do wish the endless sidetracking of threads for the likes of Katie's last name were less often. Finito.

  34. homedesign | | #34

    I am suggesting that Katie provide her last name
    since she is so refreshingly honest

    I hope Katie answers my questions

    please meet me in the Tavern or the "Anonymous Name Thread"

  35. Jim Merrithew | | #35

    Robert, as a result of information supplied by you and others in various GBA posts, I have become a convert to the benefits of cellulose. Your list of the advantages of cellulose is very useful. However, there is one detail that nags at me. As I travel from one place to another on recycling day, I often see bins of newspaper sitting out in the rain. I wonder ... 'How long does this wet material sit around in a warehouse before it becomes insulation? Is the newsprint a breeding ground for mould during this time? Is there mould present in the cellulose before it is shredded and treated with borate?' Have you, Martin or any of the other contributors encountered research about this? Thanks - Jim

  36. Riversong | | #36


    The company I purchase from, National Fiber, uses only post-industrial waste newsprint. They initially tried to be more ecological by using post-consumer waste paper but found it was too contaminated. Unlike some other manufacturers, they don't use cardboard but only virgin newsprint left over from the printing shops. And they use only borates for fire retardant. Some cheaper product uses ammonium sulfate, or a combination of that and borates, but that can offgas (like the Chinese drywall) and cause corrosion of metal fasteners such as truss plates.

  37. Jim Merrithew | | #37

    Thanks Robert.

  38. Katie | | #38

    Mr. John Brooks -- allow "Katie" to introduce herself. I am the marketing manager for an installer of spray foam and other types of insulation, as well as fireproofing, in residential and commercial applications. We service the Northeast and Mid-Atlantic regions. My last name? Irrevelant. But I'm pleased to meet all of you and open to lively and positive debate and conversation.

    We've been installing spray foam for nearly a decade, and in that time have installed just about every product from every manufacturer you can think of. We were installing spray foam long before it became the popular thing to do, and long before the "green" movement became de rigueur, because we believed in it. And we still do, for all its benefits.

    Mr. Riversong: We've seen mold issues with cellulose and have seen it go up in flames in clouds of toxic black smoke. We've seen mold issues with jean insulation. (I know nothing about light straw clay or wood chip clay and therefore cannot comment on its green-ness.) Can you call a product that might attribute to mold or gives off noxious fumes, "green"? I don't know -- depends on your definition of green, I guess. In my book, no. (We all know spray foam is combustible, but we don't market it as green). I think we respectfully disagree with each other on the issue. And that's okay -- that's why forums like this exist.

    Mr. Brooks: If there is a spray foam issue directly affecting a homeowner's/building owner's health and safety, as a contractor we are obligated to inform them. Like, if they are sensitive to smell, for example, or are asthmatic. If building code dictates a thermal barrier is required for their application, we tell them. If spray foam isn't the best product for their application, we tell them. As far as percentages of attic applications that we've done requiring intumescents, I couldn't tell you. We've done hundreds of spray foam jobs over the years. I wasn't asked about the max thickness for foam, so therefore didn't comment on this. However, there are max thicknesses that manufacturers recommend, and obviously we don't go against their recommendation, but do homeowners necessarily need to know that piece of information? Do we need to bog them down with such minutiae? In most cases, no.

    We've had little complaint from any customer about spray foam, other than the initial smell, and that's usually from from allergy/asthma sufferers. The vast majority of our customers are pleased with the outcome -- lower energy bills, less drafts, etc. We still believe that spray foam is more a nuisance to installers when it's being applied than the cured foam is to building occupants once the job is all said and done. That being said, we continue to push the manufacturers we deal with for disclosure on such things as chemical ingredients and soy content, and find that they're starting to come around. Mr. Harmon / Mr. Chandler: I thought you might find that tidbit especially encouraging.

    We welcome any open dialog about spray foam--good and bad--as the industry continues to grow.

    Katie McVay
    Marketing Manager
    Tridon Industries

  39. homedesign | | #39

    Thank you for your comments.
    I thought you were a hit and run poster.
    It turns out that you are not.

    thank you for returning and responding to my questions.

  40. Riversong | | #40


    Thanks for identifying yourself and your business affiliation. You appear to be one of the more responsible foam insulation installers, but one of your statements suggests that you engage in the same type of misleading marketing that is endemic to the spray foam industry - the R-value vs air tightness trade-off:

    However, there are max thicknesses that manufacturers recommend, and obviously we don't go against their recommendation, but do homeowners necessarily need to know that piece of information? Do we need to bog them down with such minutiae? In most cases, no.

    Installed thickness and installed R-value and whether that R-value meets the IECC minimum requirements is hardly "minutiae", and any marketing agent who would withhold information from clients is reasonably suspect of putting profit before people.

    We've seen mold issues with cellulose and have seen it go up in flames in clouds of toxic black smoke. We've seen mold issues with jean insulation. (I know nothing about light straw clay or wood chip clay and therefore cannot comment on its green-ness.) Can you call a product that might attribute to mold or gives off noxious fumes, "green"?

    It is with this statement, however, that you exhibit either a profound ignorance of insulation materials or a deliberate intent to distort the facts.

    There is no reliable evidence of a mold problem with cellulose insulation (which has been installed since the 50's though mostly since the 70's), your anecdotal assertion notwithstanding.

    Borate-based cellulose insulation contains an EPA fungicide which resists the growth of mold, even when exposed to conditions favorable to mold growth, and resists insects and vermin.

    "The borates in cellulose insulation provide superior control against mold. Installations have shown that even several months of water-saturation and improper installation did not result in mold."
    - Built Green Colorado, Steve Andres, October 5, 2007

    "Mold, is not generally found in cellulose insulation. We believe based on our own field and lab investigations that the fire retardant chemicals used to treat cellulose insulation appear to also resist mold growth."

    "I have yet to see a moldy cellulose insulation sample."
    - Jeffrey C. May, author of "My House is Killing Me!" and a home inspector

    While cellulosic materials of all types, including wood framing and the paper facing on drywall, can become food for mold, mold growth requires warmth and concentrated moisture. Because cellulose quickly redistributes moisture, it tends to prevent the local concentrations that allow mold growth - and can even protect wood framing from mold.

    Spray urethane foams have a flame spread Index ≤ 25 with 15 min. thermal barrier and a smoke development index ≤ 450. It produces highly toxic smoke in a structure fire.

    Cellulose with borates has a flame spread index of 15-20 and a smoke development index of 0-5. Installation of cellulose in a wood-frame wall increases its fire resistance rating by 15 minutes. The International Building Code (IBC) 2000 & 2001 Amendments also allow electrical outlet boxes to be installed on opposite sides of a one-hour firewall, if they are offset by 3.5 inches of cellulose insulation.

    Cellulose is permitted as an alternate to the fire blocking in Section R602.8, Item 1, of the IRC by Omega Point Laboratories, Report for Project No. 16094-11638. When installed in a dry or spray application to a depth of 14.5 inches, cellulose outperforms conventional wood fire blocking in fire blocking tests.

    Cellulose is the safest insulation material in a house during a fire, slowing the spread of the fire and contributing almost nothing to the smoke generation.

    I think we respectfully disagree with each other on the issue. And that's okay -- that's why forums like this exist.

    There is nothing "respectful" about propagating erroneous and misleading information, which both the fiberglass industry and the spray foam industry has routinely done. The issue isn't one of polite disagreement or differing opinion, but rather who is representing facts and science and who is propagating misinformation.

    And the reason forums like this exist is to thresh the wheat from the chaff, challenge erroneous beliefs and false advertising with science and fact, and create a better-informed consensus about what is truly green and what is merely hype.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |