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Spray foam odor

pins2621 | Posted in General Questions on

Just had a question when it comes to spray foam odors. Everything that I have researched online about spray foam says that it should not give off odors if it is installed properly. It has been a week now that they finished spraying closed cell insulation in my half story and it still has a scent to it but not a fish smell like most people say just a odor like a new substance was installed for example if you paint it gives off a scent. This odor is only in the half story and you can not smell on the main floor at all. It was and still is around 40 degrees when it was installed so not for sure if that is keeping the smell less potent since people say when it gets warmer the smell can get worse. I also had a box fan exhausting out the half story for three days which helped but after turning off it came back. So is it normal for spray foam after being installed that it will have somewhat of a odor like paint does after being put on? Also would this fishy smell be pretty potent and obvious compared to just a smell that a substance gives after being installed? Finally what would be a good way to find out if it is a bad install other than just relying on the smells? Any help appreciated just want to be sure I don’t have a bad install.

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  1. Expert Member
    BILL WICHERS | | #1

    When I did a bunch of ccSPF in a renovation in my house last fall, I had it done on a Friday and then left town for the weekend. I left some windows cracked while I was away. It smelled a lot when I left, less so when i returned but still very noticeable. I think after maybe a week or so it was much reduced but there was still a smell similar to how new paint has a smell for a while.

    I’d wait at least a week or two for the worst of the smell to dissipate. If the foam was not applied correctly, you’ll have some gooey spots. Everything should be pretty hard (for closed cell), or at least completely dry, if it’s applied correctly. Nothing should seem wet or sticky.


  2. BrianPontolilo | | #2

    Before, you get too concerned, I'd wait a little longer and continue to ventilate the spaces where the foam was installed. However, if the odor persists, there may have been a problem with the installation, which is the most common cause of lingering odors. Unfortunately, this is a common story, something I heard about many times while I was working at Fine Homebuilding. Check out this article, which I think will answer a lot of your questions, and please let us know how things work out.

    1. Expert Member
      MALCOLM TAYLOR | | #3


      I know this is a judgement call - but given the frequency of stories about problems with spray foam, and the consequences of a defective installation, do you think it is simply too risky a technique for builders to rely on?

      1. BrianPontolilo | | #5

        This is a judgement call...

        Like Bill points out below, for every story we here about a bad install that leaves an odor or worse, the house catches fires, there are who-knows-how-many successful installations. So the key, like anything else in home building, is to find a skilled and experienced spray foam contractor.

        It does seem that with spay foam, the stakes are higher than with other types of insulation. A poor fiberglass install (and as we know, there are many), leaves the homeowners with a poorly insulated house. As I noted, a poor spray foam job can leave an odor or do much worse.

        It seems like there was a period in the early 2000s when a few brand-name spray foam companies threw a lot of resources at sales and market and lots of architects and builders jumped on board with the promise of great R-value and air sealing in one step. But it didn't take long before many of those architects and builders moved away from spay foam as they found that alone it wasn't a sufficient air barrier and has other drawbacks, like higher global warming potential, when compared to some other materials (never mind the risk of a bad install). In recent years I've seen more and more high-performance homes that don't have spray foam anywhere in the envelope.

        So, it can definitely be installed well and can be an effective insulator and part of a home's air barrier. And it may have some additional benefits. For example, I've heard from a few homeowners in urban areas who love how quiet their spray-foam-insulated home is. And there are instances where it is a problem-solving option.

        The bottom line for me, if I were building a new home or remodeling a home that didn't have any particular tricky-to-insulate area, I would opt for other types of insulation.

  3. Expert Member
    BILL WICHERS | | #4

    I think we hear about bad stories with spray foam because they are bad. I suspect there are far more good expieriences that just aren’t talked about so it skews some people to think there are more problem installs out there than there actually are.

    I also think there are a lot of new and inexpierienced spray foam contractors out there. I used someone I know from my commerical work. I had some time to talk to him on my project at home and he said it’s super critical that the foam compound is applied at the correct temperature and pressure to ensure it mixes properly as it’s applied. He was constantly calling out to his crew while working having them make changes to the pressure and temperature settings on his rig.

    I think there is some skill involved in getting a good spray foam application so expierienced contractors are important here.


  4. jrkd2015 | | #6

    I have a similar install with closed cell SPF. The presence of odors is an indication of misapplied SPF and the only way to know for sure is to have a core sample tested by a laboratory that specializes in SPF analysis. Its a very expensive process but well worth it. Our SPF looks normal but looks are deceiving especially when applied off ratio. The first thing you should do is to reach out to the installer and the manufacture of the SPF. Let me know if you need more guidance.

    1. Expert Member
      BILL WICHERS | | #7

      For clarity, the presence of odors long after installation is a sign of misapplication. There will be some smell for at least a few days after application and that is normal.


    2. homeowner007 | | #8

      @JRKd2015 if you have the names of a lab for SPF testing I'd appreciate it - I'd like independently confirm what product was sprayed in my attic.

  5. Robert Opaluch | | #9

    I guess many of you would consider me too opposed to site-applied closed cell spray foam.  But it pains me when people like pins2621 bring up their problems and worries about mis-applied site-applied spray foam.  Again and again it happens.  And again and again you suggest "competent professional" to consumers who don't know if their contractor or sub-contractor is all that competent. Or they just blew it on your job.  And you mention global warming potential, but then say its okay to do anyway.  Any you mention high cost. Hey, can't you just tell people:  Site-applied spray foam is too risky, it has too many negatives, including high cost, high global warming potential, possible (but unlikely) health risks, possible high cost of removal then needing to redo the job anyway, possible legal entanglements if you want to get questionable work redone or reimbursed, seriously affecting construction schedule, and creating a great deal of anxiety when there's already too much anxiety in building projects...   Why not just find another alternative, just for the reassurance of being safe and not taking unnecessary risk??  There's enough risk and high cost in construction and renovation already.  And there's enough excuses out there for causing global warming whenever we use concrete or other products, why not draw the line?  Site-applied closed cell spray foam is not a good practice IMHO, so avoid it whenever possible. Or maybe avoid it always.  I know GBA tries to be a big tent that doesn't want to be too exclusive, but if you value the planet, some things you gotta state you do not support any longer.  Hey I used a lot of XPS over 35 years ago, but I oppose using it today.  We change our minds as new data and new products become available.  Site-applied closed cell spray foam is so yesterday.

    1. aunsafe2015 | | #10

      Robert, out of curiosity, are you purposefully limiting your post to closed cell? Or do you also think the risks of open cell outweigh the rewards?

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