We just had fiberglass batt insulation installed in the crawl space under our house. There is a strong odor coming from the crawl space that was not there this morning before the work was done.

I've never smelled anything like it and it is hard to describe. It's sickly sweet and also reminescent of something charred or slightly burned. It is what I might imagine burned cotton candy would smell like, maybe, but with other overtones as well. It's quite unpleasant.

I realize this isn't a lot to go on, but does anybody have an idea of what the odor might be, and if it is harmful? I would not have expected fiberglass insulation to have any odor at all.

I've emailed the contractor and asked for MSDS but probably won't get a response until tomorrow or Monday.

1 Answer 1


Your comment about "burnt cotton candy" triggered my memory of this article that I read a while ago. From Green Building Adviser on smelly eco-friendly fiberglass.

The article describes the glue used as having a sweet burnt smell:

According to Frank O’Brien-Bernini, an Owens Corning vice president and chief sustainability officer, “The new binder was introduced a couple of years ago. We have totally converted our entire product line to this product.”

O’Brien-Bernini admits that you can smell the binder when you open a fresh bag of insulation. He reminded me that old-fashioned formaldehyde-based glues also have an odor — one that is sometimes compared to cat urine. “Our prior insulation also had an odor to it that was far less pleasant,” O’Brien-Bernini said. “When we started developing this product, we did an aroma test. Most people said the new aroma is far preferable to the aroma of the prior product.”

  • That's it exactly! "Burnt brownies" is a good description, though it's a lot less pleasant. Commented Jul 8, 2016 at 14:49

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