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Q&A Spotlight

Does Spray Foam Insulation Off-Gas Poisonous Fumes?

Open- or closed-cell spray foam insulation is a great way to get air sealing and insulation in a single step, but the health implications are fuzzy

Spray foam is a great air seal and insulator, but the jury is still out on the health effects of possible fumes.
Image Credit: Daniel Morrison

Spray-foam insulation has become a weapon of choice for many builders and homeowners trying to build tight, energy efficient houses. And with its long list of attributes, that’s no wonder. It fills tiny cracks and fissures in walls and roofs to form an effective air seal. The high R-values of closed-cell foam pack a lot of punch in a small space, and closed-cell versions can block the movement of moisture into wall and roof cavities. Expensive as it may be, it’s at the top of its class.

But does this miracle material have a darker side? Dan Fette’s question about the potential hazards of spray foam launched an extended thread containing enough anecdotal information to give a few readers pause for thought and dissuaded others from using foam at all.

Polyurethane foam is a two-part compound mixed at the job site as it’s sprayed from a high-pressure gun. Although some of its ingredients are nasty at the time of application, when it cures the foam becomes an inert material that should not off-gas any harmful chemicals. That, at least, is our common understanding and the word from manufacturers and installers.

Typical are these words of assurance from Foam-Tech:: “Urethanes are non-toxic and only require protection for our operators during installations, but the finished product is completely safe and has no formaldehydes.”

Some dissent from the field

But that sunny expectation doesn’t always pan out. An anonymous poster reported developing a serious chemical sensitivity while building an “uber-green” house, which included non-toxic wood finishes and closed-cell polyurethane foam.

“I became ill after moving into the house two years ago, and had to move out,” Anonymous wrote. “Any exposure to the indoor air induces neurological symptoms…I never had these sorts of problems before that I know of.”

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  1. user-757117 | | #1

    Caveat emptor...
    I can understand the initial appeal of using spray foam products as they seem to present a solution to many design problems at the same time. I'm surprised though that more consumers don't seem to be taking a more active role in researching the pros and cons of insulating this way. I know guys that have literally taken years to decide on what TV to buy but after only one or two episodes of their favorite renovation show are ready to seal their homes up with spray foam.
    To the pros:
    Is it common to have knowledgable customers that want to be part of the process of design and material selection?
    Is much effort put into involving customers at the design stage when material choices are still being made?

  2. user-757117 | | #2

    And you want to use this where?
    From the NRC document cited above:

    Polyurethane is best used in a cool, dry environment. A good design
    will ensure its protection from extremes in temperature and from becoming
    wet. It will also keep the foam dry by providing a vapour barrier that
    will keep excessive moisture from entering the material and condensing
    or freezing in the colder parts of the foam. Polyurethane does not have
    good freeze-thaw resistance. If the material is wet and is subjected to
    freeze-thaw cycles it may disintegrate after only a few dozen cycles.

    Is this really the best product for insulating roofs?

  3. Kyle | | #3

    Recent EPA, OSHA, NIOSH,SPSC web-seminar on SPF app safety
    Here is a PDF of presentations made during an EPA web-seminar from December 2nd on SPF safety concerns. Pay attention to pages 68-77 as these pages summarize regulators current concerns. This topic is something to follow as proper safety guidelines evolve over the next few years.

  4. Kyle | | #4

    Concern of off gassing in basement applications?
    Building Science Corporation often uses SPFs (as described on this site) in bellow grade applications as part of a foundation wall sealing strategy. Does moisture concerns in this type of application pose additional off gassing concerns, especially if ground water levels change in the future?

  5. Bill Clark | | #5

    Yellow Press at Work ???
    So start with a tainted headline, then add a few comments from "anonymous" posters and follow up with misinformation about spray foam's suitability to be used in building anywhere? You could just as well run this story in the National Inquirer...

    I hate to ruin a good story with "Facts", but just for fun:

    Spray Foam Insulation uses an "A" and a "B" raw component. When these two materials are combined they form a completely different material that no longer has any of the hazards of the of the original raw materials used to make the final product, which is pretty much inert after it is formed! A+B=C the chemical reaction transforms the raw materials into an entirely new composition.

    Yes, the raw materials have some hazards listed on the MSDS sheets and must be handled correctly with proper worker protections, but once they are properly applied, the hazards no longer exist and any "off-gassing" that may occur is not detectable 24 hours after application.

    The "Canada" study is from 1977(!) and lists foam raw materials not used for many many years, but is used to support his idea of improper testing and "Potential" problems...

    The EPA study lists the dangers of the "raw materials" and health issues to installers IF they do not follow widely know and simple steps to protect themselves from contact with the materials in their "raw" form, not to mention that these effects and/or safety precautions are not even valid AFTER the spray foam is installed.

    Yes - vapor barriers are required in some climate zones on EVERY type of insulation sold today. Vapor Diffusion is the only force that could allow small amounts of moisture to slowly enter spray foam, but in residential construction, it is a force weak force/drive. To insinuate that spray foam insulation could "disintegrate" after being installed into a home's roof system due to these conditions, is simply untrue and could not happen except for highly unusual conditions, or massive design flaws.

    Zero air leakage on a home is the correct target amount, then supply the proper amount of ventilation AND performance test all combustion appliances for proper operation under "worst case" pressure conditions. This is the only way to create and operate an energy efficient, healthy indoor living environment.

  6. Riversong | | #6

    Now Comes a Foam Fundamentalist to Attack the Heretics

    Bill Clark: "This is the only way to create and operate an energy efficient, healthy indoor living environment."

    Whenever anyone insists that there is only one proper way to do something, you can be sure that he's an advocate (propagandist) rather than an objective commentator.

    I agree that the outgassing poblem is largely overblown (except for those few who have become chemically-sensitized and have to spend the rest of their lives avoiding the world), but there are many legitimate arguments against the use of a petrochemical, high-embodied energy, non-renewable, non-recyclable, non-permeable, difficult to remove, problematic for renovation, and expensive insulating material.

  7. user-757117 | | #7

    Information for all
    It's true I do have my own personal reservations about the use of spray foams (most of which are described by Mr. Riversong's list above) and maybe I should be less careless about how I express those reservations.
    The point I was hoping to make was that the consumers that buy these products should have adequate factual information to base their desicion on. As you pointed out, the NRC study above is perhaps out of date but there is very little other impartial information to read on the subject. This obviously isn't the fault of the spray-foam industry but the better the information, the better things are for everyone.
    I'm not a chemical engineer but your assertion that A+B=C is hard for me to believe. Regardless of how good a mixing system you have, I doubt it's 100% efficient at making C from A and B (therefore there must be some small amount of A and B left over).

  8. Bill Clark | | #8

    Mr. Riversong

    If you are going to Quote people, please use the entire quote:

    Zero air leakage on a home is the correct target amount, then supply the proper amount of ventilation AND performance test all combustion appliances for proper operation under "worst case" pressure conditions. This is the only way to create and operate an energy efficient, healthy indoor living environment.

    I never indicated what system was best, just the steps that need to be taken...

  9. carpeverde | | #9

    Does Any Post-Installation Data Exist?
    Has any independent party actually taken air samples from the interiors of homes insulated with spray foam and compared the samples with similar samples taken from "control" or conventionally-built homes of similar age to determine whether there are toxic elements present in the spray foam house samples? Look first for the presence of the compounds "A", "B", or "C" or other chemicals listed in the MSDS's of spray foam.

    Remember though, that the spray foam house will likely be much tighter than the "control" homes and may likely trap chemicals picked up from wood sheet goods, framing, insecticide, etc. at a higher concentration than the non-foam houses with higher air changes per hour.

  10. Michael Park | | #10

    Safety is in the proper use.
    I have used Spray Foam on several projects and it has been bery successful with no repercussions. We well ventilated the ares during application and the applicators wore the proper protective clothing and breathing gear. It was left to cure for several days before enclosing. AS with any product proper safety practices should be followed. I prefer to use this over fiberglas bats and other insulations.

  11. Anonymous | | #11

    Frankly, I've no axe to grind, but Clarks comment makes sense, and Riversong's comment makes it look like he doesn't understand anything.

    Colley above has a very good point - foam makes a tight house. Therefore all the other offgassing will remain. Is this foam's "fault"? No, but its clearly an issue that must be managed. And yet another example of why energy recovery ventilators should be mandatory.

    In my personal experience, I've been pleased with foam, and continue to use it, though not for everything. I have chemical sensitivity issues, much as I hate to admit it, as most people who focus on them are raving loons. So I don't hang around while the foam is installed. After installation I have noticed precisely zero effects, and have it in my own house.

    Its still a bit on the cost prohibitive side - framing from scratch I'd think seriously of using ICFs and thus being able to ignore the whole issue.

  12. FlownOver | | #12

    Not a tough answer to get
    Getting good hard data should not be very difficult. Build a large number of test installations, monitor the atmosphere under different conditions. It would be difficult to recreate all of the ways this stuff has been used, so such data could be rigorous, but not exhastive. If some conditions produce higher outgassing, build more test installations, and find out what variables have the most effect. Really, just basic science. Of course, facts can often kill a fun arguement.

  13. Jim | | #13

    My experience and opinion
    I agree with much of what Bill has stated. Nothing is perfect, but it must be tested. I'm not an expert, but I have used cellulose, fiberglass, and foam. Fiberglass and cellulose require protection, also.
    Are they as bad as foam offgas? I don't know. I can see little strands of fiberglass and cellulose floating in the air when I'm working after a installation. Does that mean that I should be wearing protective clothing and mask to keep from itching from the fiberglass and breathing both? In reality, I don't think many contractors do. They come down from the attic and shake off the fiberglass to float around the air.
    I'm not a chemist, but I could see A+B=C. I would think that it is plausable. When the two parts of epoxy are mixed together they form a something that is hard and unlike the two parts orignal parts. I think cured epoxy is realitively safe.
    I agree that more up to date research should be done. Why isn't there something more current than 1977?
    I like the way foam adds more rigidity to a structure when sprayed on framing members, so I like it's permanence. Should it be more recycle friendly? I don't think fiberglass is recycled, and it is probably the most common type of insulation. How does the foam made from soybeans stack up?
    Just my thoughts.

  14. john rusnak | | #14

    chemical combos
    Sodium a deadly metal element plus chlorine a deadly gas element= table salt NaCl. I have never been exposed to either elements shaking table salt on goodies like fries. Foam is the SAME.

  15. Kevin Brodie | | #15

    High -embodied enrgy, petrochemical, etc.
    Mr. Riversong makes a good point about "petrochemical, high-embodied energy, non-renewable, non-recyclable, non-permeable, difficult to remove, problematic for renovation, and expensive insulating material." However, the long term benefits of less energy consumption should outweigh these concerns. I assume that as spray foam becomes more prevalent it will one day be recyclable. The same long term benefits outweigh the "expensive" comment as well. I just used this on an interior renovation with 2x4 studs, 2x6 rafters, and existing radiant heat. The client wanted a cathedral ceiling and using spray polyurethane allowed us to keep the existing framing so it pretty much evened out cost wise. My client was in disbelief that the room went from 40 degrees to 68 degrees in about 20 minutes after the foam was applied. Now that zone barely calls for heat anymore compared to the fiberglass batt used previously. All insulation is covered by 1/2" gypsum and latex paint film. I can't imagine a lot of off-gassing from this. A whole house using spray foam should have an HRV system anyway.

  16. user-757117 | | #16

    Is there such a thing as 100% certainty?
    Phenol Formaldehyde is an adhesive chemicaly unique from either of its components, phenol and formaldehyde. MSDS for products using Phenol Formaldehyde indicate some very small amount formaldehyde off-gassing.
    A chemical reaction that is 100% efficient must be a rare bird. How efficient is the reaction between A and B ingredients? Is it as effecient as the process of thermosetting Phenol Formaldehyde resin? If not then there must be some (small) amount of A or B left over after the reaction has occured and the foam has cured.

  17. Wayne | | #17

    John Rusnak may be correct when he talks about NaCl or table salt but the analogy does not carry over to the foam case. The question is are the components A and B mixed precisely in the proportions required to make C. If not there will be some A or some B left over and where small amounts at the parts per million level are important the ratios have to be that precise. I doubt any foam equipment is that accurate in their mixers. The real question is what happens to the leftovers.
    In the table salt case, any leftover raw Na or Cl has long left the scene since the material was deposited millions of years ago.

  18. David Posada | | #18

    Lingering odor from low density SPF
    I'm witnessing an insulation retrofit using low-density spray foam, Demilec Sealection 500, in an old house in Oregon where there is a strong odor two months after installation. It is a somewhat sweet ammonia-like smell.
    8" SPF was sprayed to the exposed underside of the roof sheathing in the attic and crawlspace, and the rim joists in the basement. A low-rise mix was blown into to the exterior walls.
    The odor is strongest in the attic and crawlspace and spreads into the second floor area through small penetrations in the ceiling and attic hatch. Installation was done in med-December with temps in the 40's.
    The occupants have been running a fan in the second floor bathroom 24/7 to reduce the odor since installation and cracking a bedroom window to negatively pressurize the house and ventilate the sleeping area. The attic hatch has occasionally been left open to the second floor during the day to provide some ventilation of the attic air.
    Some sources have suggested that an improper mixing of the A and B components during installation can cause long term odors. Two spray foam discussion threads suggest that too much amine catalyst in the B component, poor ventilation of the area, and possibly too thick an application of the foam can emit odors for long periods of time. Some have suggested it may be cause to remove and re-install the foam, others disagree:
    Much of the published information regarding low density spray foams addresses the low- or non- toxicity of "properly cured" or "properly installed" foams; little seems to be said about what constitutes a improper curing or installation, what chemicals can be released, what hazards (if any) may be present, and what remedies are appropriate.

  19. user-757117 | | #19

    Well said. That's

    Well said. That's exactly my thought.

  20. Mike O'Brien | | #20

    What David Said, Plus--
    There's also the immediate issue of small droplets of foam entering the air during installation. While they probably fall out quickly, applicators are supposed to wear protective clothing and masks to avoid inhaling, so is that completely safe?

    In the long term, unlike fiberglass or cellulose, foam sticks to some components in assemblies, which may make them hard to deconstruct.

  21. kooldave | | #21

    Foam Insulation
    All the comment has been about sprayed insulation. Has there ever been any comment about sheet goods applied to the exterior of the homes sheathing ?

  22. Bill Burke | | #22

    Would anyone consider Air-Krete? My understanding has been that this would be an excellent choice for a home for a chemically sensitive individual. I've watched it being installed in one building, but have no experience with it personally.

  23. ben graham | | #23

    Long term benefits?
    When I think of a good long term solution to insulation or any enclosure materials what comes up for me is renewable, non-toxic, affordable, high-performance. Foam gets 1 out of 4 here for me. When comparing insulation performance, foam may have the best per inch but I have seen plenty of structures insulated to a higher degree than foam insulated structures I've seen, albeit thicker walls. This seems to be more of an issue of design.
    So while its important to know the facts about how toxic a material is both in structures and in the landfill(is this another long term benefit of foam?), if we were to think about long term performance in a wholistic way, foam just doesn't stand up.
    If all this energy efficiency hype is based on concern about carbon in the air and created a balanced carbon cycle. One of the best ideas I have heard is to keep the long term carbon stores in the ground.

    To chime in on the efficiency of getting A+B to equal C, I know a local contractor that didn't get it right on a roof installation. This is not a regular occurance though. I have never heard of an situation where people ended up with toxic air from a cellulose, or wool batt or strawbale installation. Just the potential for a mistake will turn folks off, just look at the nuclear debate. I think once someone has figured out how to make foam with something other than petroleum that is non-toxic with no risk, then there won't be any more debate. Until then, I think there will always be two sides.

  24. Richard | | #24

    Obtaining information on foam insulation
    I am going through an upgrade now in areas of my house to cure insulation problems such as a large knee wall area where the ceiling insulation was never completed. I thought originally it could all be done by foam. One bid by an installer mentioned the brand of open cell foam he was going to use. I made a Google search and found - hidden deep - some cases of sensitization and related problems. The literature is dominated by the manufacturers and installers claiming safety among many other things. If older people have asthma or allergy problems, then let the installer explain how they will vent the areas to be sprayed and let them explain their qualifications and maintenance of equipment. Nothing was ever said to me about ventilation or when it would really be safe to go back into the house.

    When I have watched shows like "This Old House" or even more recently "Holmes on Homes" almost always there is either a new house or large cleared areas being corrected and refurbished. Particularly in "Holmes on Homes" he uses foam a lot and has expert contractors doing the work. Neither show talks about the safety issue vis-a-vis the occupants. Also both shows are atypical since they always have real experts and professionals doing the work.

    In our project we thought the risk was too great so we went back to having contractors bid with conventional materials. I do not want people to proclaim to me that A+B=C, therefore there is no problem, particularly when they know the guns may not be well maintained and the mixing may be incomplete, and when they know the operators may have all sorts of different training. The cannisters may have bad batches, etc., etc. If everything goes right with real pros doing the job, foam appears to be an excellent material. I just cannot take that chance in a closed-in home with some upgrades being done. Will the contractor warranty to me in a written contract backed by a big insurance policy that my family will have no post-install contamination problems? Well if A+
    B=C, as some have previously stated, that should be a no brainer, and we can proceed.

  25. Wenzel Bartlett | | #25

    spray foam chemistry
    There are some really good points made in this discussion about spray foam insulation. Here are a few important details on the chemistry. I hope it helps the discussion.

    My understanding is that spray foams used in residential construction are all polyurethanes. The polyurethane spray foam is made by mixing the A and B components. The A component is a highly reactive and toxic chemical that has at least two isocyanate functional groups (i.e. PMDI). The high reactivity of the isocyanate is a desirable property when manufacturing polyurethane materials, including residential spray foam insulation, but it is also the property that makes isocyanate chemicals toxic. The B component is primarily made of polyols, but there are many other additives mixed with the polyols (i.e. catalysts, antioxidants, uv inhibitors, etc). The formulation of the B component has a big influence on the properties of the polyurethane (i.e. are you making a car seat, mattress, shoe sole, insulation for walls, refrigerator, ice chest, packaging material, and many, many more products that we use every day). Polyols can come from many different sources including renewable crops and petroleum. However, the manufacture of polyols from petroleum is typically less expensive and typically produces a polyol with properties that are easier to control.

    Ideally you do want complete reaction of both the A and B components, hence they are typically mixed in stochiometric ratios. A chemical reaction between an isocyanate functional group and a hydroxyl functional group forms a urethane functional group and carbon dioxide. The reaction is extremely fast, exothermic (releases heat), and not reversible. Since the A component has at least 2 isocyanates in its chemical structure and the polyol in the B component has numerous hydroxyl groups in its chemical structure, mixing components A and B will form polyurethanes and carbon dioxide gas. In the few seconds that it takes for this chemistry to occur, carbon dioxide gas bubbles through the polyurethane as it grows, cools, and turns into a solid plastic material. Hence, carbon dioxide creates the foam.

    Since you can't really mix the perfect stochiometric ratio, it is safer to add a slight excess of component B to the mixture. Component B is not a very reactive material (other than with isocyanate). It is highly unlikely that the low level off gassing in the polyurethane foam is the isocyanate of component A. Isocyanate reacts with many other chemicals, including water. In fact, it reacts with water even faster than it reacts with polyols. Hence, if the isocyanate were off gassing it would react with water vapor in the air. It is far more likely off gassing is either excess polyols or some of the additives in component B.

    When we insulated our new house with spray foam insulation, I thought the smell from the foam followed a similar trend as fresh wall paint. The smell was strongest when first installed and then it went away over time. Supplemental ventilation in our HVAC system helped remove new construction odors from our house to the point where I don't smell any odors except in the attic, which smells more like wood with a slight hint of spray foam. We've been living in the house for 2 months.

  26. [email protected] | | #26

    Open Cell Spray Foam & Vapor Barriers
    It appears most of this thread is aimed at Open Cell Spray Foam - the soft kind you can crush in your hand. It goes by the trade names of Icynene, Bio-Based, Demilec, and others. It is vapor permeable and so requires a vapor barrier, and many building codes make that a requirement. In heating climates, the vapor barrier is put on the inside of the insulation.

    For walls, Open Cell Foam is generally over sprayed and shaved flush with the studs. Drywall and latex paint form an effective barrier, though gaps around outlets and such often get little attention. For unvented cathedral roofs, or vented attics with the insulation at the ceiling, the same applies. That is, when drywall & paint are in contact with the foam, they serve as a vapor barrier.

    But, for attics where the foam is sprayed to the underside of an unvented roof, Open Cell foam requires an additional vapor barrier. Typically, 2 coats of latex paint can be sprayed directly to the foam. This provides the required vapor barrier IN CONTACT with the insulation, and also serves to seal the off-gassing potential. The same is done for Open Cell foam used in band-joist applications where the basement is left unfinished.

  27. Marlene | | #27

    To the Skeptics - Especially Mr. Bill Clark
    I really don't appreciate labeling the health probelms my brother has experience as "yellow press".
    He has saved his entire life to build this house and hired a licensed contractor to install the Icynene. He is in the process of seeing doctors since this installation because he has been chemically sensitized. As for the chemical process, we sent samples of the "cured foam" curing since December 2009 to a chemical company for testing. There is definitely remnants of icynene in the foam. Mr. Clark, why do you think anyone at 65 years of age would make this stuff up?!? My brother is trying to build a home to live in during his "golden years" which have turned into "hell" as a result of this product. Whether it is due to improper mixing of the two-part components or to a problem with the chemical itself, someone needs to be held responsible for this travesity!

  28. Marlene | | #28

    Correction -To the Skeptics - Especially Mr. Clark
    Specifically the chemical component remaining was "Isocyanate".

  29. Marlene | | #29

    People with Chemical Sensitivities are Raving Loons?
    This is also a rather ignorant comment. My brother is a Vietnam vet who fought for his country and has worked his whole life. He has saved to build this house, pay cash for it and used the Icynene, as it is supposed to be superior for insulation and be good for people with sinus problems. He is definitely a good conservative Republican and really doesn't like Governent intervention as a general principle. the icynene company advertises as being able to inhabit 24 hours after installation, yet I see many entries regarding waiting several days/weeks to get rid of any potential off gassing. Being unable to breathe after being exposed to this stuff definitely does mark him as a "raving loon", but a good man who has had the unfortunate experience of believing the advertised claims of this product.

  30. Neeva-Gayle Candelori, Director of CPI | | #30

    Spray Polyurethane Foam Health and Safety Information
    I’d like to share some information that may be helpful. As mentioned earlier in the dialogue, spray polyurethane foam (SPF) is a highly efficient insulation product and without question, it is critically important that it be installed safely and according to model and local building codes which provide guidance and requirements on the safe use of materials and systems used in buildings. Interest in this product is likely to grow right along with increasing demand for greater energy efficiency in homes and buildings. The makers of SPF know that this interest is growing, and want to provide further education and outreach about the safe use and handling of this product. That’s why the Center for the Polyurethanes Industry (CPI) and the Spray Polyurethane Foam Alliance (SPFA) have launched an industry product stewardship program enhancing national health and safety practices for the SPF industry in the United States.

    If you haven’t already seen our new SPF health and safety website, take a look, and I encourage you to visit it often. You’ll find many guidance documents related to SPF ranging from personal protective equipment during SPF installation, ventilation techniques, good safety practices, health and safety Q&A’s for interior or exterior SPF application, preparing a site for SPF application, “green” marketing claims, and more. There’s a lot of useful information and guidance regarding SPF product stewardship and the website will be continually updated as new health and safety information becomes available.

    Neeva-Gayle Candelori, Director
    Center for the Polyurethanes Industry
    of the American Chemistry Council

  31. Wenzel Bartlett | | #31

    spray foam under roof decking
    I have an alternate opinion on the need to apply paint to spray foam that is applied to the underside of roof decking. When the underside of a roof is insulated, you essentially create a semi-conditioned space in the attic. In my house, the attic is just a few degrees warmer than the rest of the house. That means that I am willing to go up in the attic any time. For this reason, I had the framers deck the entire attic so I could use it as extra storage space in the house. If there is a leak in my roof, then I want to know about it so I can get it repaired as soon as possible before it damages any of the wood. If the underside of the roof is covered with paint or some other vapor barrier, then it will be more difficult to tell if and where the leak is located. That said, I did use a roll plastic roof underlayment on the top side of the decking instead of roll felt paper. So it is true that I do have a vapor barrier on my roof.

    A couple of other issues have been brought up about the attic during my house construction. One is that spray foam will discolor and degrade if left exposed to UV light. I have windows in the gables of my attic. I leave the windows closed and they have a good rating for blocking UV light. So far I have seen no discoloration of the foam.

    The other issue is regarding ventilation of the attic. My HVAC guy believes there is enough leakage through ceiling fixtures to ventilate the attic, but my energy efficiency consultant believes that I need to provide mechanical ventilation by adding a very small air flow from the HVAC system. The intention is to dehumidify the attic since the wood is still drying out. I'm planning to add the mechanical ventilation.

  32. Steve Dearlove | | #32

    A Poisoned World
    I am about to install spray foam in my new house and so I find all this discussion of great interest. I do believe the benefits outweigh the detriments: prudence, with anything these days, is always wise.

  33. Anonymous | | #33

    There are two issues at hand here...1.) health concerns prior to the foam insulation being created, 2.) health concerns after the foam insulation is manufactured and cured.

    1.) Obvious safety risks here. A building product is being custom manufactured in your home for each wall cavity. Yea, there are going to be some health concerns here.

    2.) Once the foam has cured - IT IS CHEMICALLY INERT. Foam insulation is the same product in your pillows and mattresses.

    A lot of information above has the health and safety concerns confused. FYI foam insulation is recommended by the American Lung Association for healthy homes (that is because foam insulation is chemically inert and does not sprinkle nano sized fiberglass shards in the air). If your an installer, wear the proper safety equipment while installing. If your a building occupant of a foam insulated house, there are ZERO health concerns related to indoor air quality or dermal absorbtion.


  34. GBA Editor
    Martin Holladay | | #34

    Thermal barrier
    Your installation raises questions being debated elsewhere on this site — namely the question of requirements for a thermal barrier. It sounds like you have exposed spray foam in an attic with a floor that you visit frequently because the attic is used for storage. Some building officials require a drywall layer covering the foam in attics like yours.

  35. user-757117 | | #35

    Let's get rid of confusion
    Agreed, properly installed and CURED foam (C) is probably not a health concern.
    It's not clear to me that even in perfect laboratory conditions, there are ZERO unreacted remenants of either A or B (or both) ingredients after mixing.
    If there are unreacted remenants of A and/or B after an installation, where do they reside? Do they all dissipate completely into the environment? Is it at all possible that some of those remenants remain within the cured foam?
    Though the cured foam itself is inert it may be trapping toxic compounds that may then escape to the outside over time. This may be an insignificant amount of off-gassing to most people but it seems that there are some cases where it is not.
    If someone has specific information that either supports or refutes this thinking I would love to see it.
    There needs to be more unbiased and impartial information provided to consumers. The people who are to actualy live sealed inside the foam bubble need to know exactly what the potential risks and benefits are before the installation occurs.

  36. user-757117 | | #36

    Health concerns aside
    There are plenty of other issues that consumers should also be informed about when making the decision about whether or not to use spray foam.
    The concept of providing high R and air sealing in one step is appealing but for the cost there are other ways to air seal and insulate to high levels.
    The sustainability of using petrochemicals to make homes more energy efficient is debatable.

  37. Steve Dearlove | | #37

    Lucas Durands Comments
    As usual, the industry touts the benefits; the skeptics ring the alarm bells and nothing ends up being definitive... until after the damage has occured. (Toyota. Ford Pinto. Thalidomide along with countless other pharmaceuticals)

    "for the cost there are other ways to air seal and insulate to high levels"

    What are these other tried and true tested/safe methods? (Fibreglass is out and not strawbale as it's too late for that for me.)

  38. GBA Editor
    Martin Holladay | | #38

    What's your question?
    Please give us details about your insulation project.
    1. New construction or retrofit?
    2. Basement walls? Above-grade walls? Sloped ceiling? Flat ceiling with attic above? Somewhere else?

  39. Steve Dearlove | | #39

    Thanks Martin. It's new
    Thanks Martin. It's new construction. Spray foam for all above-grade stud framed walls as well as the rim joist perimeter. (2x6 construction with 2" of poly extruded on exterior.). All roof construction is SIPS. Region is Southern Ontario.

    My mechanical design is hinged on the high R values.

  40. GBA Editor
    Martin Holladay | | #40

    You asked about alternatives to spray foam — "What are these other tried and true tested/safe methods?"

    1. If you are planning to use open-cell spray foam, then you should know that dense-packed cellulose will provide the same R-value.

    2. If you are considering the use of closed-cell foam, then you will need thicker walls to provide the same R-value with cellulose. That can be accomplished by installing horizontal interior strapping or by using double 2x4 stud walls.

    3. It's hard to beat closed-cell spray foam for rim joists. It's the best material for this area.

    4. No matter what insulation you choose, you need to do a meticulous job of air sealing. Spray foam does not address many potential leak sites.

  41. Steve Dearlove | | #41

    Help Appreciated
    Thanks Martin. I think I'll stick with the closed cell and face the potential risks. (There's too much water under the bridge regarding framing at this point.)

    I have exposed areas of spray foam installed in my current home (as retrofit) for over 5 years and cannot claim any negative effects... mind you, my memory is failing, but I suspect that's got more to do with stress and age!

    I wil be diligent about the air sealing. ;-)

  42. user-757117 | | #42

    Just for the record...
    The building code of Canada suggests that any of the following materials can form part of an air barrier system:
    OSB, plywood, drywall, rigid insulation, polyethylene, metal or glass.
    Of course many other materials are suitable as an air-barrier as well.
    Many of these materials may already be specified for use within your new home and could be installed so as to provide the function of an air barrier. Air-tight drywall is a good example.

  43. reis | | #43

    closed cell in the cold
    i am currently remodeling my attic space. (i'm in portland, or) I am vaulting the ceilings and have 2x4 rafters. I really want to use close cell SPF, but am not yet convinced for a couple reasons. The main thing i'm confused about is the vapor barrier question. If the closed cell acts as a vapor barrier and doesn't allow the outside air in, or inside air out, would there be a moisture build up on the interior of the house? Especially in the winter, when it's cold outside and warm inside and any vapor in the air inside the house could condense against the colder ceiling. I've always assumed there needs to be some built in venting for the ceiling/attic space, however basically all literature i've read about closed cell says you don't need to vent the roof.

    any thoughts on this matter?

  44. GBA Editor
    Martin Holladay | | #44

    Interior moisture build-up
    Whether or not a house has high or low indoor humidity during the winter depends on several factors, including the number of occupants, the home's volume, the frequency of certain activities (showering, cooking), the number of houseplants, whether there is a fish tank, and whether or not the occupants store firewood indoors.

    Ventilation channels adjacent to roof sheathing and attic ventilation were never intended as remedies for a house with high indoor humidity problems. Oddly, though, some builders treated them that way. If you ended up building a leaky ceiling, and indoor humidity escaped into your attic or got between the rafters of a cathedral ceiling, then the ventilation chutes were supposed to help carry away the moisture. But the fact that the moisture was even there was evidence of sloppy building practices.

    The usual remedy for high indoor humidity during the winter is mechanical ventilation (bath exhaust fans, a supply ventilation system, or an HRV). Once your ventilation system is installed, you can adjust your ventilation rate to meet your home's needs.

    If you choose to install closed-cell spray polyurethane foam, the foam (if properly installed) will act as an air barrier and a vapor barrier. There shouldn't be any risk of interior air or interior water vapor contacting your cold roof sheathing.

    Choosing open-cell foam is more risky, since open-cell foam is not a vapor retarder. There have been reports of wet roof sheathing and wet wall sheathing in cold-climate homes insulated with open-cell foam. This is a vapor-diffusion problem. The usual solution is to install vapor-retarder paint on the inside surface of the cured foam.

  45. Ravi | | #45

    The idea of giving high R and
    The idea of giving high R and air sealing in one step is demanding but for the price there are other methods to air seal and protect to high levels.

  46. Haris | | #46

    According to me if there is a leak in my roof, then I want to know about it so I can get it repaired as soon as possible before it damages any of the wood.

  47. Anonymous | | #47

    Alternatives to Spray Polyurethane Foam
    I would like to get some ideas about alternative insulation materials which could be used in an unfinished attic of an old Michigan home. The attic rafters are exposed and after insulation I would cover them with dry wall. As I have a husband who is highly sensitive to any chemical smells I want to avoid any toxic material.

  48. GBA Editor
    Martin Holladay | | #48

    Toxic insulation
    As far as I know, products sold as insulation and installed as directed are not toxic. If your husband has special medical issues, the best place to get advice on this question is from your husband's doctor.

  49. Chris in OK | | #49

    Icenyne - 5 Years No Barrier - Water Standing Open Tastes Bad
    In 2005 I build my home on a remote Western OK ranch. The walls are ICF, the roof conventional truss, the decking OSB, the roof semi standing seam metal. Given the huge mismatch in thermal mass and insulating potential of ICF versus a 'stick built' roof, I wanted seal and insulate the roof really well in this very hot climate. I don't believe in venting if you can seal a roof solid, so I went for spray-on foams.

    Icenyne was installed, fulling filling the 2X10 top chord space, then sawed back flush. I was not here when it was installed. My wife reported that the installers struggled some trouble with their truck during installation, but the foam all looks consistent in cell size and good in all the exposed areas, and we have no detectable residual odors. What is uder the exposed foam, as to some areas blown on way off stoichiometric, I have no way of knowing directly.

    This foam has remained standing open these last 10 years with no vapor barrier, and we have only curtains and not doors between the utiltities service runs of the 'attic' and our bedroom and office. One complaint is when we fetch stuff from the attic and rub agaist the underside of the roof, we get 'foam buggers' on our clothes.

    For ventillation of this very tight house we have an ERV or energy recovery ventillator, which runs most of the time, exchaging air with the outside.

    I have been concerned about outgassing for three reasons:

    - After installation something all the exposed copper wires of our electrical work in process

    I attributed this to outgassing from the foam during cure. Later, when I heard horror stories about Chinese drywall, I checked that out too. Nope, I have American drywall, and there are no odors.

    - My wife and I have noticed that to this day a cup of water standing open next to our bed will have the water tasting funny by the morning, and worse if left there a few days.

    This one fact makes me very concerned, because whatever is creating the off taste has to be coming from the air. I will do an experiment (should have done this before) to leave the same water standing open in a space not having icenyne foam as a control. If the water does not change, there is something reacting with the water in the air. That would be scary, as I am mostly made of water!

    Now I suppose I could have this water examined, control and experiment, for chemical differences, but don't know where to send the water to. It seems we are talking very low ppm here.

    - I have developed a cluster of possible auto immune-related problems.

    The first is aching in the joints. This has been with me since before I have lived in this structure, but has gotten worse with each passing year. I attributed this to age (I am 53) and past body abuse. Last year I developed Papulo-pustular Rosacea, a skin problem with some auto immune component. The cause was ascribed to stress at work. The Rosacea responded well to a treatment similar to acne treatment, with a blast of Azithromax followed by daily dosing at sub-therapeutic levels of slow-release doxycylene that is supposed to be more anti inflammatory than antibiotic. I have also developed some sensitivity in the colon to foods. Some irritability. I used to be able to eat anything. Now I have to watch it.

    I am otherwise robust and healthy. I understant the human tendency of 'perception is reality', and want to examine this objectively and not get carried away with the kind of blame the other guy thinking that is ruining our society. Objective is to test the water. If something is in there the next step would be a barrier to slow outgassing. Given the very rough surface of the exposed, sawed icenyne, I suspect paint will be a piss-poor sealer, more feel good than anything. The attic does not allow putting up drywall. Just not enough room, and plastic sheating will just get torn off as we pass through.

    Any suggestions, comments?

  50. Anonymous | | #50

    Response to Confusion by Anonymous and others
    The American Lung Association (ALA) has never approved or endorsed spray polyurethane foam insulation, or any insulation type for that matter. The ALA does have a "Health House" program but they do not specify certain products or types of materials. They have established "Health House" criteria and these are the following, as excerpted from their website:

    What are the typical components of a Health House® Home?

    Foundation waterproofing and moisture control
    Advanced framing techniques
    Air sealing and advanced insulation techniques
    Energy efficient, high performance windows
    Energy efficient and sealed combustion appliances
    High efficiency air filtration
    Whole house ventilation
    Humidity control
    Carefully selected and reviewed interior finishes

    There have been a couple of marketers of polyurethane spray foam insulation who have claimed it is approved by the ALA in some of their advertisements, but this is not true and is deceptive marketing. In truth, spray polyurethane foam insulation was just used by a builder who built a house according to the ALA criteria and the house was given the Health House designation. And of course, with all the deceptive advertising being spread about this insulation material-- "no off-gasing, green, made from soy beans, eco-friendly, all natural, bio-based, etc.", it is easy to understand how the true health ramifications of this material could be overlooked. The builder himself, most likely didn't know the truth about this material.

  51. Anonymous #3 | | #51

    The realities of spray foam installation A+B does not equal C
    When manufacturing spray polyurethane foam insulation in a house or building, it is very difficult, if not impossible, to get a full and complete reaction of the diisocyanates (part A) with the polyols, flame retardants, catalysts and other ingredients (part B) due to a large number of factors, so A+B seldom ever equals C.

    If you have ever watched and studied the foam insulation manufacturing process, especially the operators and the equipment, and then thought about the physics and chemistry of making spray polyurethane foam insulation on-site in a building (which is a lot less controlled than making polyurethane pillows, mattresses and other polyurethane products in a factory) it becomes quite obvious that a perfect reaction seldom, if ever, occurs.

    The key factors involved in making spray polyurethane foam insulation in a building or house that mitigate against A+B=C include:

    1. Operator(s) knowledge, training, skill and diligence.
    2. Quality of the mixing of the ingredients at the spray nozzle.
    3. Cleanliness and maintenance of the spray nozzle.
    4. Maintenance and performance of all other equipment, including the pumps, the heater, the proportioners, the hoses, the supply tanks and the quality or purity of the part A and part B ingredients.
    5. Pressure at the nozzle
    6. Temperature of the ingredients at the nozzle
    7. Ambient temperature
    8. Humidity
    9. Wind
    10. The type of surface it is being sprayed on.
    11. The temperature of the surface.
    12. The moisture content of the surface.
    13. Heat build up in the sprayed on foam layers.

    With so many variables, it is inevitable that A+B will never fully = C and that part A and B vapors, unreacted aerosols, reacted fine particulates, overspray and other combined or uncombined ingredients will be generated during the process. This is why the SPFA and CPI recently created a new website emphasizing all the health and safety precautions that workers must take to prevent damaging their own health as they are spraying polyurethane foam insulation in a building. There are always unreacted vapors and residuals to which exposure needs to be prevented. Otherwise, spray foam operators would not need the personal protective equipment, including fresh air-supplied respirators. The new SPFA/CPI website is found at:

    So the next question is where do these toxic residuals go that are generated when a worker produces spray polyurethane foam insulation in a building or someone’s house, that the workers themselves are trying to prevent exposure to? Do they just disappear? Of course not, they suspend in the air for a time period, some of the gases migrate to other areas of the building, some evaporate, or in spreading to other areas become diluted with air to below harmful levels. The particulates or aerosols remain suspended for some time, and then eventually settle out on the floor or other surfaces in the building. If unprotected individuals enter the building too soon, or if the building is never ventilated properly or the settled particulates never cleaned up, there is the likelihood that these unprotected individuals will be exposed to these chemicals through inhalation or deposition on the skin. Make one of these individuals a diisocyanante sensitized person with asthma, and you may have a serious health problem.

    Finally, with so many factors that prevent A+B from ever fully equaling C, one must ask the last question -- when these factors compound, will the final foam insulation product be created correctly and will it be fully chemically stable or inert? If the foam is not produced correctly (given all the factors described above), will there be an imbalance in the chemistry of the finished foam that could lead to off-gassing and the vapors or odors that people claim they are experiencing? If this is the case, then the final insulation foam may not be fully inert.

  52. Ravi | | #52
    Well we can say that if there is a leak in a roof, then one should get it repaired as soon as possible before it spoils any of the other wood.

  53. Phil_in_FL | | #53

    Removing the fumes
    I had an install done of 6.5" of Sealection 500 2 months ago, and had residual fumes which I found irritating to my lungs, and smelled sweet - I assume this is Isocyanate. I called the company that installed it, and they set up an appointment for Demilec to come out and check out my install. Not sure what they'll do or say yet, but in the meantime, I found a satisfactory (temporary) solution. I bought some bulk Activated Charcoal, made a makeshift filter with fiberglass and the charcoal, attached it to some fans, and put the fans in the attic, as well as a HEPA filter - with the fans running, the strength of the vapor is much much lower in the attic, barely noticeable, and completely unnoticeable in the house, and my lungs are no longer irritated. I'm not satisfied for the long term with having just a "small amount" of the vapor in the attic, so assuming it's not decided that a complete removal/reinstall is necessary, I plan on just ramping this up and putting much more activated carbon / fans in the attic, adsorbing the vapors until they are completely gone. Unfortunately, I've read that MDI has an extremely slow evaporation rate, so I'm not sure if it will ever completely finish outgassing in my lifetime.

    I believe the problem with my install was they did not ventilate the attic during the install, and while I paid for 6.5", I think there is probably 8-10 inches in most places, and it wasn't applied in layers -- I've read that for thicker installs you should do multiple thinner coats to allow for a more proper curing.

  54. Dave | | #54

    Question to Phil_in_FL "Removing the Fumes"
    Phil, I am in a similar situation. Do you mind letting me know what the result was after the Demilec representative came in to your home? Was there any solution? Did they discuss removal of the foam? Demilec is also coming in to my home this week.

  55. Phil_in_FL | | #55

    Demilec's rep said "it smells
    Demilec's rep said "it smells like foam" and that it was not an acceptable level of outgassing, and they are trying to work out a solution with the installer to either use a fogger (no details yet on what they would be aerosolizing, but i plan on studying the msds before allowing it) or fans to enhance ventilation.

    In the meantime I have been dealing with this as much as i can, as this is clearly a higher priority for me, and I would rather work on fixing this problem than do nothing:

    1) rigged up fans on my own connecting to a duct i ran from the attic to the outside. The constant negative pressure in the attic has very noticeably reduced the smell to an undetectable level in the house, and much less strong in the attic.

    2) placed air filters around the house with an activated carbon and HEPA layer

    3) placed around ten new houseplants throughout the house (Plants actually use many airborne toxins as food and filter the air)

    I did not ask about removal as I believe the cause of the problem was inadequate ventilation during the install and that likely the vapor is trapped mainly in the wood and not the foam, so removing it would be pointless, and possibly create a new problem due to dust creation, and there is no question that this stuff is highly effective as insulation.

    Its too early to tell, but i think the strength of the odors exhausted is going down which suggests that more ventilation will solve this. I think with the amount of ventilation I currently have (estimated at 300 CFM for a ~2700 sqft attic) it will take 1-2 months 2-4 months to achieve zero odor in the attic. Also, I noticed and demilec confirmed that outgassing is accelerated when heat and/or humidity is high, which is bad as far as odor in the house is concerned but good as far as ventilation is concerned.

    I suspect when summer is over, even if nothing was done, the odor will go away until next summer, but assuming nothing is done by demilec, I plan to ventilate as much as I can this and if necessary next summer until the odor is completely removed, even in the attic.

    Also, most of my guests can not smell the odor, except in the areas i can smell it strongest. Both my girlfriend and I can smell it all over if the fans are not running and we come home after being away for a few hours, but lose the sense of smell except in the strongest areas after only a few minutes. Our main concern is the health effects og the gas, not the smell.

  56. Dave | | #56

    Demilec Technical Rep Visit
    Thanks for all of the information Phil. I will update the post further after Demilec visits my home which will hopefully be soon. You are welcome to contact me further at [email protected] if you would like to communicate further about the problem and solutions.

  57. Anonymous | | #57

    Take the warnings seriously !!!
    used closed cell foam in my basement. Installed by a reputable installer. I thought I did my homework. Discounted the opinions on this site. Now 2 months later. Outgassing wont dissipate. Had I known, I would never have used the stuff ! Take the warning you read here seriously.

  58. Anonymous | | #58

    The OTHER foam insulation -- Air Krete
    I'm amazed that in the article itself or the ensuing discussion, no one has mentioned Air Krete until now ( If you go to their web site, you can see a great descriptive video segment from Renovation Nation.

    The basic raw material components of Air Krete are water, magnesium oxide, and ceramic talc, mixed together with compressed air and non-toxic foaming agents to form a very lightweight & fluffy MGO cement. When wet it looks and feels like shaving cream.

    Unlike chemical foams, this material is completely non-toxic and fireproof; but like chemical foams it's pest-resistant and provides excellent air-sealing -- in addition to insulation. Al Gore insulated his personal estate with Air Krete in October 2007.

    I insulated my own home with Air Krete two years ago, and I LOVE the result. The insulation and air sealing is nearly (not quite) of Passive House quality. There is absolutely no smell or odor, and my friends with chemical sensitivities have not even noticed its presence.

    No product is perfect: the two biggest drawbacks that I know of are (1) price, and (2) drying time INSIDE enclosed cavities. Let's discuss these potential drawbacks separately:

    Until recently, Air Krete was patent-protected; now that the initial patents have expired, we may see some competition (and the falling prices that come with it).

    The drying question is more complicated: I insulated my home by pulling off the interior walls. The installer then put up a lightweight mesh screen and shot Air Krete foam through it. As long as the interior walls remain off for at least a week after installation there is no problem, but I've heard that if it's shot into a closed wall cavity, Air Krete can take a long time to dry. IF this is true, it would limit the usefulness of Air Krete in situations where a homeowner doesn't want to put up with the mess and expense of removing interior walls. (I plan to test the closed-wall drying time in another installation quite soon.)

    For open-wall installations there's no contest: when Air Krete and similar products become more available and the price drops -- I can't imagine why green builders would want to use anything else.

  59. 2tePuaao2B | | #59

    No Brainer
    This stuff is dangerous, why do GBA advisors tip toe around it? Much less advise it's use as Green????

  60. GBA Editor
    Martin Holladay | | #60

    Response to Roy
    Can you please show me somewhere where one of the Green Building Advisors declared that spray foam is green?

  61. 83xJyfqaJU | | #61

    How is Spray Foam a Green Product
    There is nothing in the product that is not man made. All chemical based. It emits a gas. And the gas is played down because Dow, and a few others that have allot of money invested in it and have attorneys that can keep studies from popping up. Remember how the Freon in your car was bad so Dow and the boys came up with new and improved. It was about money and patients.

  62. 83xJyfqaJU | | #62

    Future Law Suits
    The day may come when Spray foam is deemed unsafe because of emissions (gassing) and by that time the manufacturers will have made tons of money the law suits will be small in comparison. The Soy base Foam has 2% soy in it to make its claims of green. 98% same out stuff.

  63. 4HCR9rhnie | | #63

    Spray Foam Problems
    I had Demilec Sealection 500 (two part open cell urethane) installed into my home this past November. It has been an absolute nightmare. Same issues as other posters. Constant odor and associated resperatory distress. Unlike other homeowners, I ventilated the space from day one (for four months now), and it has not helped one bit. I have spoken with the EPA and I am in the process of undergoing independant air testing. From my discussions with EPA it has become apparent that removal of the foam can create its own set of new problems as airborn particulates created when the foam is disturbed can present additional problems. I Am a lawyer, though I do not specialize in tort actions or product liability. I am however looking to connect with other homeowners who have had a similar problem. I have little doubt that in the end I am going to have to tear out the shingles, roof decking, and rafters to resolve this nightmare. God only knows what the long term effects of this exposure will be. I would like to coordinate a discussion group and share experiences, health problems, and test results.

    This is not meant to be an attack on the industry. I am not trying to engage those of you who have had good results from properly installed foam. My concern is finding a way to help myself and those others who have experienced the nighmare of issues relating to an improperly installed product.

    Pease contact me at [email protected] only if you are experiencing similar problems.

    Upstate NY.

  64. Harsdesigns | | #64

    I was at a Eco-friendly new residential construction open house and the basement walls were sprayed with Icynene and were exposed. The house has been up for over 4 months. The smell was so nauseating I had to leave. I am not chemically sensitive but it was so overpowering. It must have been still off gassing to create such an odor.

  65. wS77DrpEsJ | | #65

    Studies of remaining free isocyanate in polyurethane foam
    I'm coming to this discussion rather late, but because most of the data in this thread is anecdotal or speculative (not that anecdotes and speculation don't often lead to the truth!) I thought some scientific articles would be helpful, and I'm lucky enough to have broad library access. As you might expect, the articles fall on both sides of the issue, but they do correct some common misconceptions:

    I found only one useful study of spray-foam installation, which found that isocyanate levels during spray foam installation generally exceeded OSHA limits, although levels of free isocyanate were undetectable 75 minutes later. However, a different study suggested that sensitized individuals can react to isocyanates at concentrations below the detection limit, so this doesn't necessarily exclude the possibility that someone sensitized during installation (or in a completely unrelated event) could continue to react afterward.

    I did find several articles about remaining free and bound isocyanate groups in polyurethane foam in general.

    One lab tested a variety of consumer products (beds, sofas, etc.) and found that detectable levels of free isocyanates can remain in foam for up to 30 years, although concentrations were significantly higher in newer foam (detection limits ranged from 1.3 to 2.7 micrograms per gram).

    Also, according to this study, in foam manufacture, an excess of isocyanate is always used, although as one earlier commenter noted, an excess of polyol would be safer. I couldn't find an explanation for this choice. Another study (albeit one done in 1965, so to be taken with a grain of salt) found that free isocyanate remained even when less than the stoichiometric amount of TDI (toluene diisocyanate) was used. In general, the use of blowing agents (which speed up the reaction time) increased the amount of free isocyanate remaining.

    Another study (by Dow Chemical, and thus to be taken with even more salt than the old article) found that after 3 days, polyurethane foam did not produce high enough air quantities of TDI to be of concern, but it did tend to trap (which is different from reacting with) greater than 99% of free TDI present in the air. Other studies pointed out that various conditions (e.g., contact with skin oils) could free that trapped TDI.

    Although isocyanates are extremely reactive, they can remain surprisingly stable residues -- one study found significant amounts of unreacted isocyanates (up to 1.08 mg/kg) on 5 of 19 polyurethane-laminated food packages.

    Finally, the effects of isocyanates on health are poorly understood. One new-ish theory that seems pretty convincing is that skin contact with low levels of isocyanates can be sensitizing and can lead to more generalized immune responses (e.g., respiratory problems and increases in allergies). There are also studies that blame polyurethane exposure for the rise in childhood asthma.

    Full disclosure: I became interested in this topic because I have severe asthmatic reactions that always seem to occur in the presence of polyurethane foam, so I was trying to figure out if it was the culprit. Thus I'm not entirely impartial.

    For those of you who have access, here are the links to the most relevant articles:
    Airborne Methylene Diphenyl Diisocyanate (MDI) Concentrations Associated with the Application of Polyurethane Spray Foam in Residential Construction

    Isocyanates in Flexible Polyurethane Foams

    The determination of the ability of polyurethane foam to release toluene diisocyanate into air.

    Polyurethanes and childhood asthma.

    Liquid chromatographic determination of residual isocyanate monomers in plastics intended for food contact use.

  66. user-1146678 | | #66

    Come to my house and smell it yourself
    I do have the rotten fish smell BASF blue closed cell foam and Icynene.
    Both smell differently and it gives me a headache. I will be removing the Icynene now, the BASF was (thank God) installed outside where it doesn't bother me that much

  67. airtight-reg | | #67

    It is my belief and has not been proven that when you make a house airtight by using polyurethane it's not the polyurethane off gas you need to worry about it's the off gas of all the products in your home. Caulking,glues in plywood,chemicals in your furniture,cleaning supplies etc. Polyurethane is buy far in my opinion the best way to insulate but you must have an air ex changer to remove the off gas of "all the products" in your home as they will be trapped and move fresh air through out your home. It also helps to flush toxins from your body! by doing some type of toxin body flush.

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