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My house inspection noted that the exposed blue foam insulation in my basement is not to code and (if there’s a fire) could be dangerous due to noxious fumes. The insurance provider has told me to remove it, or cover it with drywall to ensure ongoing coverage. I am trying to decide which path to take, without spending a large amount of money.

Options (as I see them):

  • Remove it
  • Cover with drywall (without framing) and using concrete news/screws
  • Vapor barrier, frame it, cover it with drywall (probably not actually an option because I can’t afford it with current lumber prices)
  • Something else?

More Context: I’m in Atlantic Canada (winters are long and cold). The house is old (1928), and already not very efficient. The basement is not usually wet, but there can be some pooling/dampness when the snow thaws in spring. With this in mind, I’m worried that covering the blue foam with drywall might present a mold issue unless I invest much more money in the solution.

Question: Am I crazy to remove the foam entirely? Will I be affecting efficiency a ton by doing this? (this is my favorite option)

Additional context:

  • The foam does not cover all walls. Probably about 2/3 of the basement wall surface is covered.
  • I have no plans to ever finish the basement
  • I can’t afford to fully waterproof my foundation at this time (we have a sump pump, and that will have to do for now)

Covered section of wall (see damp staining)

Uncovered section of wall

isherwood
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    First I would verify that the foam is a problem contact the MFG, I can’t even count the number of times a home inspection has made claims that are not fact! – Ed Beal Jul 13 '21 at 13:47
  • How thick is the foam? The thicker it is, the greater the R-value and the more insulation value you'd be losing by removing it. If it's 1/4" (~6mm), you're not losing much. – FreeMan Jul 13 '21 at 13:52
  • I think this is https://www.dupont.com/content/dam/dupont/amer/us/en/performance-building-solutions/public/documents/en/SC00133-STYROFOAM%20Brand%20SM%20Insulation-PIS-Digital2.pdf - although in normal use it is supposed to be on the outside of the foundation. – Jon Custer Jul 13 '21 at 14:01
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    4/6? Looks more like 8/12 to me. :P – isherwood Jul 13 '21 at 14:28
  • You'd have to do the math to calculate heat loss with respect to your heating system, heating habits, fuel costs, etc. No one here is going to be able to give you a confident answer with the little information we have. Assuming that your floor is roughly at grade, the concrete will likely be somewhere between 40 and 55 degrees F in winter (warmer down low). How much heat is lost into it is a complex thing to figure. – isherwood Jul 13 '21 at 14:32
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    I would probably remove it to appease the insurance company, then, when lumber prices aren't stupid, build energy walls throughout and reuse (or sell) the foam. That's assuming I was planning to stay a while, and assuming various other things about my life. – isherwood Jul 13 '21 at 14:36
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    What's on the other side of the foundation wall? Is it dirt or is the majority of that wall exposed to the open air? If the former then you might not notice much of a difference by removing it. If the latter then your basement will most certainly feel colder. – MonkeyZeus Jul 13 '21 at 14:42
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    While you're at it, consider getting some sort of insulation in between those floor joists in the ceiling of that cellar. It'll pay for itself in a couple of years, and the room above will warm up quicker, and feel more comfortable. – Tim Jul 13 '21 at 15:40
  • @Tim, you'd only insulate the floor if the basement is intended to be unheated. We don't know that to be the case. In fact, since there's insulation on the walls, I'd guess not. – isherwood Jul 13 '21 at 16:08
  • @MonkeyZeus, the soil up there in Canada freezes down three feet or more. You'd feel the difference. – isherwood Jul 13 '21 at 16:10
  • @isherwood - 'I have no plans to ever finish the basement.' Does that really say OP's going to heat it? – Tim Jul 13 '21 at 16:39
  • My basement isn't finished. It's a workshop and storage/play area. It's quite well heated (and insulated). Same with my previous home, and my brother's, and my dad's.... #anecdotes #ftw – isherwood Jul 13 '21 at 16:40
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    Wow, thanks for all of the great insight! For further clarification on a couple of the above points.

    • It’s mostly dirt on the other side, maybe only about 1ft exposed above grade. But yeah, it gets really cold

    • @Tim/@isherwood - The house is heated by oil. The furnace is down there, so it certainly warms up with all of the rad pipes in the ceiling, but it’s not purposely heated (although I do use it as workplace/storage too). Sounds like it could be worth throwing in some insulation between the joists at some point

     –  Jul 13 '21 at 18:10
  • Wouldn't covering the foam with drywall leave it still a fire hazard - only now one that's hidden from sight? – Vikki Sep 08 '21 at 00:53

2 Answers2

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Get that blue stuff out of there, it will burn very aggressively and turns your house into a firetrap. Houses are actually more flammable these days and stuff like that is why.

Petroleum based foam can even make a hard rock mine burn, generally thought impossible. In that incident, it was not only a powerful accelerant, it emitted toxic smoke which incapacitated people.

It's why the latest advice is to sleep with your bedroom door closed.

If you want to put up other kinds of insulation when the insane building market calms down... that's fine.

Note that the pinch point on lumber is the milling not the harvesting. if you have the means to mill logs into boards, lumber is cheap.

Harper - Reinstate Monica
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    I have decided to go with this answer because -- safety first. -- However, I have also decided to re-visit suggestions from this answer as a way to get back some of that efficiency, without risking being overcome by toxic smoke if there were to be a fire. –  Jul 15 '21 at 17:41
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The Styrofoam product and the products like it will be part of a class-action lawsuit in 20 years (like asbestos) because of how quickly it burns and the toxic fumes.

Also a note on your basement. This thin of insulation is not really doing anything other than acting as a solid barrier. Framing/drywall would do the same thing. If you are in a freeze zone in Canada you should have something much thicker there.

The other thing is your joist caps. I see that crappy thin insulation and then right above it nothing. This is the area that you have to insulate the most. If you insulate joist caps (where I see insulation on the one wall) and basically take Roxul about 1 foot out and 6" down... that provides a very tight air barrier to the outside and is the most effective way to keep a basement conditioned. R-value doesn't mean crap when cold air is getting in. Having more r-value and covering the caps is 90% of insulating a basement. The concrete itself is already doing that on the walls - yes you can add to the concrete but priority should be the top.

And based on your comments about the other side of the walls being mostly dirt with maybe a foot at the top exposed... all the more reason to be more concerned with insulating the cap area better. In the midwest we only insulate about 1' below grade So you would insulate the top 2' of your wall as there are no returns past that. Being colder climate though this top 2' is still most important but you should have r-10ish at least for the rest just for energy efficiency.

DMoore
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