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Polyurethane spray foam concerns

3rdLhJYtbj | Posted in Green Products and Materials on

FYI: I’m a consumer but really value your site. I’ve found out so much on here and hope you might help me with my query:

We have just done an energy audit on our house using the local Green
Building company. We have a lot of air coming in from our crawlspace through our wood floor, and that is the main place we need to seal up to get healthier indoor air as well as energy savings. Currently we just have (newly installed after a rodent infestation) Eco Batt fiberglass batts as insulation under there. I probably should have used the Ultra Touch cotton batts in retrospect due to less toxicity and environmental friendliness, but I was concerned it wouldn’t be good in a crawlspace environment. After further research it probably would have worked, but still would not have fixed the air leakage issue.

Please know before I go on that I have chemical sensitivity issues so this is why this decision is such a big deal to me.

Our choices to seal the area (as per our builder) are to take down the current fiberglass and tape and caulk the gaps in the floor from the crawlspace side , then either:
1.) Just put the Eco Batt fiberglass back up over it.
2.) Tape and caulk then apply rigid polystyrene foam boards (EPS) then put the Eco Batt back up. (I am almost totally going to take this option out of the equation as I heave been reading on your site all the concerns about EPS and XPS such as flame retardant chemicals and ozone depleting manufacturing practices)
3.) Take down the fiberglass and use a closed cell polyurethane spray foam product called Spraytite by BASF. The builder would like to do this option since it would totally seal the area and make it air tight. He firmly believes that after a 24 hour period of ‘curing” in which we would have to vacate the home, it is totally non-toxic and safe for chemically sensitive individuals. The BASF folks also tout this product as being safe for chemically sensitive people.…

We have the option of doing a 2” layer of the foam and then putting the fiberglass back up over it or doing a 4.5” layer and not using the fiberglass at all.

Even with all this reassurance it will be safe for me and my family. I have severe reservations about using the spray foam even though the Green Builder feels it is safe and is the best option. While I trust him, I always need to do as much research as I can due to my chemical sensitivity. I hope you might have some information that might help me in my decision making process.

Thank you, and I appreciate you reading this. I know that you are all aware how hard it is to navigate the toxic world out there and hope that you appreciate how desperate I am for more information so I can make the right decision.

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  1. JphaYjYFPw | | #1

    I am assuming that they are putting the 4.5 inches in the floor. that will be the .5lb open cell foam. DO NOT DO THAT: without painting a vapor barrier paint on the open cell foam. The manufacture has to recommend that. the 2 inch average is the right way to go and you do not need anything else like to hang fiberglass that will be useless and wasted money. Check insurance, Training, and visit if you need any more help. "2inch average of closed cell" not 4.5 inches of interior foam.....

  2. JphaYjYFPw | | #2 has the only foam that passed the NFPA-286. (not needing a fire coating), did the foamer tell you about the coating needed on the foam in the roofline? What else did he tell you that you believe to be true?

  3. GBA Editor
    Martin Holladay | | #3

    1. Your builder is right that the best way to air seal the floor above your crawl space is with spray polyurethane foam. If you decide to go this route, I would recommend that you install the recommended 4.5 inches (or more), not 2 inches. But I can't comment on your chemical sensitivity -- that is a medical question. It's quite possible that your medical condition precludes the use of spray foam.

    2. The best way to address your crawl space is to seal up any vents and to insulate the crawl space walls. That way, it doesn't matter if the floor above your crawl space isn't air sealed. Here's more information on that option: Building an Unvented Crawl Space.

  4. SLSTech | | #4

    While I can not speak tothe BASF product, we use Demilic CC Foam for chemically sensitive people & those with major allergies due to its air sealing abilities. While 1 day should easily do it, we generally recomend 2 days.
    During that time we completly air out the house & run the ERV non stop to help make sure there are no pockets of air that might contain any chemicals. While this is probably overkill (especially based on the VOC readings after just a few hours) we like to make sure.
    With that said, a sealed crawl space as Martin says is generally the best option

  5. 3rdLhJYtbj | | #5

    Thank you for your replies. I should clarify, the spray foam planning to be used is closed cell, not open cell. The builder says only closed is applicable for this situation. I don't seem to understand Eric Price's comments. I don't understand about what you mean by "foam in the roofline?" The foam would be on the underside of the flooring, applied in the crawlspace. I also don't understand about paining a vapor barrier, as the closed cell is a vapor barrier itself, right?

    As far as the other answers, thank you. I didn't post because I don't trust the builder, I certainly do, I am just really concerned due to my chemical sensitivity to try the foam option. Yes, I agree, if I am going to take the foam plunge I will go for the 4.5 inches. I think he was offering the 2 inch option plus adding the existing fiberglass on to equal R30 as a way to save money while still blocking airflow, which is the main reason to do the spray in the first place, since the crawl-floor issue was the main air leakage point in the energy audit.

    If we do the foam, I like the idea of waiting 2 days instead of 1 to return to the house, and airing it out. If we are not there, do I assume the builder would go in and air it out for us? As far as the ERV, we do not have one. We have an exhaust fan which would take the air out, but it doesn't bring new air into the house.

    As far as the sealed crawl space...Here is my question about it. It was never an option brought to my attention though the energy audit though I have read about it elsewhere. The floor of our crawl space is dirt, covered by a 6 ml vapor barrier black sheeting. The walls are concrete with vents and the ceiling just has the R30 fiberglass batts. If we were to "seal" the space with spray foam instead of fiberglass, and block up the vents and insulate the crawl walls, wouldn't we have to also do something to the floor like concrete? Because a sealed space with a dirt floor (even if it's under a poly vapor barrier sheeting) seems like a bad idea. If rodents tunnel under again up through the dirt and poly sheet there would be no ventilation and it would get really gross....

  6. GBA Editor
    Martin Holladay | | #6

    It's certainly possible to do a sealed crawl space with poly over a dirt floor. Crawl space remediation specialists do it all the time. Look at the two photos of remediated crawl spaces in the article I linked to.

  7. 3rdLhJYtbj | | #7

    Thanks Martin. just read the article. It does mention one can add a 2-3'' concrete slab over the vapor barrier called a 'rat slab'. I think that's a good idea if we go this route since the rats tunneled under the house into the crawlspace last time up through the old poly vapor barrier. I couldn't imagine the air quality concerns if they did that again and the crawl space was enclosed. I will ask my builder about this option.

    However, it seems if we decide we want to enclose the crawl, then the only option we have would be to use the spray foam, correct? I still need to get more confident regarding my concerns about toxicity and offgassing of the product due to my chemical sensitivity.

  8. GBA Editor
    Martin Holladay | | #8

    If you have a sealed crawl space, you move your thermal barrier and your air barrier to the crawl space walls. You no longer have any need to air-seal your crawl space ceiling.

    You can insulate your crawl space walls with rigid foam if you want to avoid spray foam. Of course, you still need to pay attention to air sealing at the rim joist area.

  9. 3rdLhJYtbj | | #9

    Well, that certainly makes sense. However, here is the thing...We had a major rodent infestation in our crawlspace. Rat feces, urine, dead rats, rat nests everywhere. After discovering it and trapping all live rats and sealing off all the access points with the guidance of a pest control person, we got the crawlspace cleaned by a crawlspace cleanup company. New vapor barrier, new fiberglass. However, even though the materials used are brand new and the space is rat free, I still don't know how much of the original contamination remains in the area though it looks clean visually. Sealing up the vents and thus making the crawlspace sort of like a "basement" worries me due to any residual rodent "yuck" therein. One of the reasons we got the energy audit initially was because I wanted to air seal the crawlspace ceiling so no possibly contaminated air (who knows if rodents will ever get back in there without us knowing) could pass through. We have areas where you can actually feel the cool air of the crawlspace coming up through the floor so I knew it was an issue even before the energy audit.

    So I guess we could choose to air seal the crawl and leave it the way it is, vented....Or seal it the way you described which makes good sense but I still would want to air seal the crawl ceiling, thus still going back to the issue of spray foam or not????

    A question to Martin (or anyone else), do you think if we decided against the spray foam due to chemical sensitivity concerns, would taking off the existing insulation, caulking/taping up all visible gaps and then rehanging the fiberglass be a sensible choice to consider? If we choose to do that, do you think there is any difference between Eco Batt fiberglass or the Ultra Touch cotton batting as far as helping to block air transfer on the other side of the caulk and tape? If the Ultra Touch has any superior characteristics vs the existing Eco Batt, we can always use our existing Eco Batt for another project.

  10. Foamer | | #10


    Seems to me that you have two separate (pun intended) issues. You need to prevent future rat problems and you need the best insulation strategy for your crawlspace. For peace of mind, pouring a rat slab sounds like the way to go to solve the first issue.

    As to your second problem, I would urge you to not even think about putting any kind of fibrous insulation in the crawlspace. We have removed enough of the stuff to know that it just doesn't belong in that environment.

    Conditioned crawlspaces work very well and closed cell spray foam is the most fool proof material available to construct them.. If you can stand more articles about conditioned crawls, here is a good one:

    If you are concerned about lingering effects of your rat infestation, you can have the space tested. Contact the Indoor Air Quality Association who can provide you with the names of people in your area who are well qualified to sample and test your crawlspace air.

    That leaves your chemical sensitivity issues, which could be a show stopper. When we have clients who are concerned about out-gassing, we provide them with a good sized sample of the foam to let them live with it for a while before they make their decision. I am sure your contractor will be happy to do the same. One lady put a string through our sample and wore it around her neck before she was confident enough in the product to proceed.

    Caulking and taping the crawl ceiling would be a nightmare. If you find that you are okay with the spray foam, your contractor can apply a thin coat of closed cell material to the area, which should do the job.

  11. user-939142 | | #11

    heck if you want to test your 'chemical sensitivity' have the contractor spray a garbage bag full of foam for you while they do another job. you can then bring it home and set it in your bedroom and see if it affects you for a couple of days. it is sorta silly, but about as silly as being sensitive to chemicals. the foam is inert for all basic purposes if sprayed properly. the unpleasant issues tend to come from 'baking process' that may linger at home or disturb other issues.

    i don't see EPS/XPS foam board being any different than closed cell spray as far as health issues.
    it really might just be luck if you 'feel' susceptible to a component of either, which are mostly the same

    most the eco tags on any of the foams are just marketing or twisting of misunderstood legal definitions. just because one brand passed some certification doesn't mean it is worthwhile to you, or that any other brand couldn't easily pass it as well

    realistically, if you mask everything properly or excessively and if you do some excessive venting during the spray and cure process, like a large unobstructed path between open door and basement and another open door/window with large blowers, there should be no 'residuals' left. a lot depends on your sprayer mixing and spraying properly

    note: while some like foaming the underside of the floor, others in the past have commented that it may not be so wise for a number of reasons. something to research

  12. 3rdLhJYtbj | | #12

    Hello Torsten,

    That was a very helpful reply! Thank you. I just looked up the IAQ on your recommendation but the practitioners in my area when I look at their websites seem to focus solely on mold and asbestos. Perhaps if I contacted them individually they might be helpful about air quality due to rodent issues, though it doesn't seem like they work with that much from their websites...I'm going to call tomorrow and ask them.

    The article you linked was very interesting but I have to admit after reading it I don't think I fully understood it, being a layperson myself and not a building professional. So If we do decide to go with the spray foam, do we then have the option to either create a conditioned/enclosed crawlspace with a rat slab and close the vents, or put the spray foam in and keep the crawl the way it is with the vapor barrier/ open vents around the perimeter? I ask because the quote I have for the spray foam is just for the foam itself, applied to the crawl ceiling to stop the air transfer as part of our energy assessment...It doesn't mention anything about enclosing the rest of the crawl to create a conditioned crawlspace. Because we want to do many of the suggestions which came from the energy assessment (such as sealing up all our light fixtures, replacing a door, installing new exhaust fans that run 24/7, etc) I am concerned about the cost of adding a conditioned crawl to the list. Also the builder never mentioned it was a possibility to me, I found out only through reading about it on GBA and your responses. Perhaps he doesn't do them?

    Would it be a bad move to just do the spray foam on the crawl ceiling and then not condition the space? Because with the spray foam, it doesn't seem to be a place the rats could nest in like they did with the fiberglass...So perhaps it would not be inviting. Or to do the foam and also pour a rat slab but not fully condition the space? (Leave the vents the way they are, don't insulate the walls.) I ask about these options because it is nice to know when planning financially all the possibilities out there.

    Finally, in regards to the chemical sensitivity/spray foam issue, my builder did offer to give me a piece of foam I can take home at some point. He told me to sleep next to it. So what I wonder is...This is a really small piece of totally cured foam that has been in existence for how long, maybe a year? How does it really compare to newly installed foam in a 1500 sq/ft crawlspace? I worry that even if I tolerated the small piece of foam sample, after 24 hours when we return to the house after the application of the spray...What happens if I then get a reaction? Can spray foam ever be removed if it causes a severe problem to an individual? It makes me scared to have something that I see as permanent installed in my house, not like the current fiberglass which could be taken out (and most likely will be.)

    PS...That brings one more question to mind. I guess we always have the option to do nothing at all and just leave things at the status quo if none of the other options work. You mentioned that I should "not even think about putting any kind of fibrous insulation in the crawlspace". Well, that fibrous stuff is already there right now...Other than being completely inefficient in solving our air leakage issue, and being a possible future nesting material for rodents, are there other major issues to fiberglass (or cotton batts) in a crawlspace environment?

    Thank you in advance for your advice! This forum is incredibly helpful.

  13. 3rdLhJYtbj | | #13


    I like the idea of getting a piece of "newer" spray foam to test. However, it' s not really silly like you mentioned, that I am sensitive to chemicals. It's been a huge problem in my life. I don't have MCS but I have had documented health problems to a variety of chemicals, it has gotten worse over the last 5 years. I've been treated by a MD and it's a hard thing to live with. It arose around the same time as my diagnosis with an autoimmune disease. I don't know if the 2 are related but I assume so. This is a huge part of my life, and that is why I am working with a "Green Builder" and posting on "Green builders" because I feel that you all would be understanding of those with chemical sensitivity problems.

    You stated "while some like foaming the underside of the floor, others in the past have commented that it may not be so wise for a number of reasons. something to research". I've been researching this exact issue both on this site and a variety of other resources over the last few weeks. So I don't think I have come across the comments you have mentioned about it not being wise. Can you please summarize then or direct me to a link so I can read for myself?

    PS...From my research I do see EPS/XPS as possibly a worse choice than the spray foam due to the flame retardant HBCD which it is treated with (a known health risk to humans if it gets into "household dust"--I read about it on this site specifically.) Also the CFC/HCFCs used to manufacture it are very concerning to me as well from an environmental viewpoint.. I understand spray foam is far from "green" as well, but the info I've found about the polystyrene panels has shocked me.

  14. 3rdLhJYtbj | | #14

    What do you all think about Air Krete as far as an option?

  15. YUqszt383T | | #15

    The odds of you having a chemical sensitivity to a water blown closed cell are very very slim. HOWEVER when spraying any spray foam the A side chemical has MDI 4,4 in it and that is what people are sensitive to. When using a water blown closed cell there is no off gassing to speak of once the foam is cured so sleeping with a piece of foam won't tell you anything. The MDI in a properly ventilated job site is gone with in the first 24 hours after spraying is completed.

    Make sure you find a contractor that knows how to properly ventilate your house and I would recommend not coming to the house for 2 days after completion. Demilec dealers received a packet about this issue earlier this year and other manufactures have done the same in recent months.

    Hope this helps.

  16. 3rdLhJYtbj | | #16

    I might have found an alternative!? Siga tape and Siga membrane under the fiberglass next to the crawl ceiling. I just talked to the distributor and he says no-VOC and very airtight.

    I'm still researching AirKrete (as far as a non toxic spray insulation alternative) but think it's probably not a good air barrier. I've called my local installer but no word back yet.

    I have been researching turning it into a sealed conditioned space as Martin wrote about in his great article...However even in the article it says that in our area (PNW) vented crawlspaces actually are more efficient than sealed as per a WSU study. We are right next to the area of that study so I guess save my money on the sealing and use it for more energy improvements?

    While PU spray might be very safe for 99.9% of people I still can't help but be VERY wary of anything that requires evacuating my home for 24 hours (or 48, or 72 based on different replies to this thread). So I keep looking for a better alternative.

  17. user-659915 | | #17

    Morgan, I think you need to decide your lead concern and stick with it. If energy efficiency is at the top of the heap, and nothing else really counts, leave the crawl vented and go with a spray foam solution. But if you have any concerns about chemical sensitivity, stay away from spray foam, the marginal energy benefits are really not worth it. Even of you do the take-it-home test, there's still a small possibility that your installation could go wrong due to a bad batch of materials or poor workmanship, and then that stuff will be so hard to remove. Forming the air barrier by means of a crawl space sealed with rigid foam at the foundation wall is a foolproof answer as the material can easily be removed if you have a problem. And use Polyiso board, not XPS/EPS.

    By the way, vented crawl or no, you absolutely have to deal permanently with the rat issue, period. And if you have any ductwork and/or mechanicals in your crawl space sealing that baby up is really a no-brainer.

  18. BhH5hCn7U6 | | #18


    I found your post while researching EcoBatt material. We also live in PNW and have a large crawl space like yours. We have been battling some mysterious smell in the basement for the last few months. We did do clean space encapsulation in the crawl space. But that's not the root cause of the smell. Now our focus is the existing fiber glass insulation underneath the living space, above the crawlspace. One of the insulation contractors told us if there was a mice problem (which we did, we hired a pest control to take care of those mice), their droppings and pee in the fiberglass insulation will linger for many years. The only way to get rid of them is to replace the fiberglass. They also pointed out that the penetration points in the crawlspace for the HVAC, plumbing, building vacuum, electrical are not foam sealed, which create air leak. That's why we have smells penetrating into the basement, even though the crawlspace does not smell too bad from crawlspace stand point. I am wondering whether you experience smell issue in the living space when you had the rat problem. Did replacing the insulation with Ecobatt resolve that issue?

    BTW, I don't recommend encapsulation after spending $$$$ on it. Yes, the crawl space looks very nice. But with crawlspace completely sealed, if there is any smell in the crawlspace, it will force those scents into the house. In the end, we asked the contractor to remove the crawlspace vent cover and installed a couple of crawlspace vent fans instead to improve the air circulation in the crawlspace.

  19. 48KhFGjPAX | | #19

    I hope closed cell foam works for you. But BASF SPRAYTITE has been a closed cell foam from hell for us. An applicator in SC purchased the SPRAYTITE® polyurethane foam materials from a supplier near Charlotte, NC. The crew applied it in Feb 2011 to our garage ceiling. After a week it started smelling like rotten fish. After five months the applicator removed about 60% of it and resprayed it.

    The new application seems to have less odor. But the garage still smells. I wish we had never used this product. We would NEVER use again.

  20. 48KhFGjPAX | | #20

    My suggestion is DO NOT do it.

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