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Closed-cell spray foam insulation – is it safe?

cmferguson | Posted in Green Products and Materials on

We are reading lots of things about spray foam insulation, and have just had the attic space in our new home spray foamed with a closed cell variety. We are contemplating fiberglass batting in the rest of the house after reading that the offgasses from this spray foam installation can cause respiratory irritation, even after the initial 72 hours, particularly for those already suffering with asthma. The American Lung Asssociation recommends spray foam insulation. The EPA cautions about the respiratory irritation. What to do? Is this a safe product for home application?

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  1. Siffe | | #1

    Caroline, I'm sure you'll hear arguments on both side of the fence. One of the spray foam constituents, MDI, as you may already know, is under an EPA action plan. See

    MDI is not the only potential problem; it may or may not offgass for long, but the flame retardants (HBCD, etc.) probably will offgas forever and are toxic and they bioaccumulate. No spray foam for me; the precautionary principle applies.

  2. GBA Editor
    Martin Holladay | | #2

    The vast majority of spray foam customers are happy with their choice of insulation and report no negative health effects from living in a home insulated with spray foam.

    A small minority of spray foam customers have experienced problems: Spray Foam Jobs With Lingering Odor Problems.

  3. cmferguson | | #3

    Ok, great. Now that we have this stuff in our attic above all of our bedrooms - it's all over - what could we possibly do if there are adverse health affects? There is no apparent odor at this point, but the house is not completely closed yet. Does Fiberglass present an equally dangerous health issue?

  4. cmferguson | | #4

    We have two air exchangers in our HVAC system. Does that help?

  5. GBA Editor
    Martin Holladay | | #5

    Relax. The vast majority of spray foam installations work well, without any complaints at all. If there is no apparent odor, everything sounds just fine.

    The vast majority of fiberglass batt jobs, just like the vast majority of spray foam jobs, do not result in any odor complaints or health complaints.

    When you refer to "air exchangers," I assume you are referring to heat-recovery ventilators (HRVs) or energy-recovery ventilators (ERVs). If you have either type of appliance, and if the appliances were properly installed, that means that your house should be well ventilated, which is a good thing.

  6. davidmeiland | | #6

    Is the foam in your attic exposed? If so, there's an upside, which is that you can keep an eye on what's happening up there (sometimes foam doesn't stay stuck to the framing). On the other hand, it is probably supposed to be covered with something to protect it from flame.

  7. cmferguson | | #7

    It is exposed. Is it better to have it exposed re the offgassing issue over time?

  8. GBA Editor
    Martin Holladay | | #8

    Building codes require that spray foam needs to be protected (covered) for fire safety.

    Most building codes, including the International Residential Code (IRC), require spray foam insulation (including foam installed on the interior of basement walls) to be covered with a 15-minute thermal barrier. However, if the spray foam is located in a crawlspace or an attic “where entry is made only for service of utilities,” the code permits the installation of a less stringent covering: an ignition barrier rather than a 15-minute thermal barrier. In sections R314.5.3 and R314.5.4, the IRC defines an ignition barrier as one of six permissible materials: 1 ½-inch-thick mineral fiber insulation; ¼-inch-thick wood structural panels (e.g., plywood); 3/8-inch particleboard; ¼-inch-thick hardboard; 3/8-inch-thick gypsum board; or corrosion-resistant steel having a base metal thickness of 0.016 inch. Presumably, code officials also permit the installation of thicker versions of any of the six listed materials.

  9. Siffe | | #9

    Martin: "If there is no apparent odor, everything sounds just fine."

    That statement is inaccurate. The well-known odor, when it happens, is due to underprocessing of the foam. Just because it is processed correctly and does not smell absolutely does not mean that it is not off-gassing. Neither formaldehyde nor MDI have any odor. Caroline, please read carefully the last 5 or 6 comments on the article Martin referred you to:

  10. GBA Editor
    Martin Holladay | | #10

    I stand by my advice. Caroline's house already has spray foam installed in the attic. She evidently has two HRVs. She reports, "There is no apparent odor."

    I'm advising her to stop worrying, but to figure out a way to install a thermal barrier or ignition barrier for fire safety.

    If GBA readers adopted your advice, and worried to the same level you propose that we worry, our mental health would suffer.

  11. dickrussell | | #11

    Ed Siff, you wrote: " Neither formaldehyde nor MDI have any odor." Surely you didn't mean that. Formaldehyde is among the most noxious-smelling gases there are. Didn't you dissect a frog in high school biology lab? The formalin the frogs are preserved in is a water solution of formaldehyde, and it stinks!

  12. cmferguson | | #12

    Hi there. We have Demilec Soy closed cell spray foam in the roof of our attic space. We plan to cover it with drywall. We chose not to have it sprayed with fire retardant. There doesn't appear to be any other fire retardant in it, but maybe we're missing something. So far, no smell.
    I appreciate both of your comments. Really. It's sometimes good to have both sides of the spectrum. Can you tell me what your backgrounds are with this material and in general? Thanks much.

  13. cmferguson | | #13

    We have an individual with asthma and allergies in our home already - not due to any spray issues.

  14. Siffe | | #14

    Dick Russell : I should have said formaldehyde odor is not detectable by most with low level off-gassing. Of course, concentrated, thus volatile, formalin or formaldehyde smells pretty bad.

  15. Siffe | | #15

    Martin: "If GBA readers adopted your advice, and worried to the same level you propose that we worry, our mental health would suffer."

    I don't see where I have directly given any advice. I'm simply trying to make people aware of the potential problems.

  16. Siffe | | #16

    Caroline: "Can you tell me what your backgrounds are with this material and in general?"

    Obviously, I have no experience with spray foam :-) I am a consumer with a medical background and a great interest in environment/health friendly building materials. As I and my wife both have various sensitivities, we have researched extensively for the two houses we have had built. I wish you much luck.

  17. Expert Member
    MALCOLM TAYLOR | | #17

    "If GBA readers adopted your advice, and worried to the same level you propose that we worry, our mental health would suffer."

    What absolute nonsense. Ed has pointed out legitimate concerns which may be attached to long term exposure to some of the constituent parts of spray foams. Your dismissal of this as an inconvenience to GBA readers is well beyond your remit as an advisor here.

  18. GBA Editor
    Martin Holladay | | #18

    Malcolm and Ed,
    I am an editor and journalist. My advice is given freely, and is worth no more that what people pay for it.

    Of course, Caroline has heard many pieces of advice on this page, and may prefer the advice given by Ed to the advice I have given. I make no claims to being a chemist or health expert.

    Caroline: if you or anyone in your family is experiencing health problems or symptoms, you should consult a physician. A physician is in a much better position to give health advice than anyone who responds to a question posted on this web forum -- including me, of course.

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