Spray foam insulation post-install chemical smell (not rotten fish)
I’ve read many articles on this subject, but I wanted to ask a more specific question as my case doesn’t seem to match the other’s horror stories with poorly-installed Spray Foam Insulation.
Our contractor came highly rated by a friend who is an architect in our area. He’s worked with this contractor on numerous occasions. I’d gotten quotes from ~5 different spray foam insulation vendors and this guy’s estimate was a good 50% higher than the others, but I felt he actually knew what he was doing. In conversations he seemed to say all of what I considered “the right” things. He does 100% spray foam insulation for high-end homes in our state of Connecticut.
They did a great job as far as the job site was concerned. They were extremely clean and really cared about keeping things orderly.
We had a very large job as our house is a two-story 5200 sq ft house.
They removed the blown-in insulation on the floor of the attic and sprayed BioBased 501w open cell foam on the underside of the roof deck (~10 inches on roof deck, and ~6″ on vertical walls).
Prior to spraying, they shut off the upstairs air handler that was housed in the attic and disconnected the ducts. They laid down plywood sheets on the floor and laid plastic on top of that, stapled to floor. All surfaces were covered. (A subsequent HVAC guy remarked that he’d never seen such a neat job of spray foam insulation installation.)
The foam was also covered with a fire-retardant paint ()
The contractor used an air handler in the attic that was attached to a removed window to vent the attic air to the outside.
The reason for this posting, however, is that we’re still smelling a chemical smell in the house when the vent is turned off. And this is now 2 months after the installation. Installation was done 2nd week of July and it’s now mid-September.
The smell is worse on hot days. It is not the dead fish smell that others have experienced, but it is evident.
It’s possible that I’m getting used to the smell, but my sense is that it IS getting better. Yesterday we had another 90-degree day and we could smell it and were worried, but I went into the attic and noticed that the 12-inch flexible tube out of the air-handler had detached and was not sucking air out at all.
That was actually encouraging because while there was a distinct chemical smell, it was less than it used to be. After re-attaching the air handler, the smell went away.
I know people have said the smell will never go away unless we take out the part that smells (assuming there’s an area that didn’t cure properly.)
However, I do feel that it is better. The contractor has assured me the smell will, eventually, go away.
I’ve read that if there is not adequate ventilation when the installation happens, initially, when the foam expands and forms it’s air bubbles it will pull in the accelerant gas that is present in the air. That slowly leaching gas can lead to a smell.
If this is what happened, it seems reasonable to me that the lingering (and decreasing) smell may just take awhile to go away, since this was a very large job. Plus the surface of the foam was covered in that thick, fire-retarding paint. If there is a gas in there that needs to come out to be replaced by fresh air, that paint has to be slowing the process, right?
Does this idea make any sense to any professionals on this list?
I have a call in to an air-quality tester to see if we can determine what the chemical smell is, and to set a baseline to test again later to verify whether it is, indeed, going away.
Looking for any guidance on this issue.