I first heard about the problem of smelly fiberglass batts from Michael Maines, a builder and GBA blogger who lives in Portland, Maine. Maines sent me an e-mail saying, “The latest problem with fiberglass insulation is that it smells like burnt brownies!”
I’ve collected a half dozen reports of this problem, all centering on EcoTouch brand fiberglass batts manufactured by Owens Corning. Two years ago, the company switched from a formaldehyde-based glue (or binder) to a new glue described as a “bio-based” binder.
Descriptions of the problematic odor vary. The odor has been compared to burnt cookies, burnt cotton candy, and burnt glue.
I interviewed two contractors who have had this problem. The first person I interviewed was an insulation contractor who was very forthcoming, but who prefers to remain anonymous. “It smells like something you burned in the oven,” my informant told me. “It’s a sugary smell — not a bad smell. The smell usually goes away if you air it out. But in this case, it just didn’t go away. They waited for the smell to go away before they put up the Sheetrock, but the smell never went away.”
At first, the contractor assumed that the smell came from another product. “It was a flash-and-batt job, and when I heard about the smell, I was worried that the problem was the spray foam,” he told me. “But it turns out that the spray foam didn’t smell. They were smelling the fiberglass. The Owens Corning rep came. He said, ‘We will pay to take it out and have it replaced.’ The owner didn’t want any more Owens Corning insulation, so after the smelly batts were removed, they put in Roxul. I know that this is not the first time it has happened. In one case they…