5 Things You Need to Know About Vermiculite

Updated: Dec. 21, 2023

If your home was built before 1990, you might have vermiculite insulation in your walls or attic.

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What is vermiculite?

Vermiculite is a mineral that was used for insulation. If your home was built before 1990, you might have vermiculite insulation in your walls or attic. Up to 85 percent of all vermiculite insulation in the U.S. came from a mine in Libby, Montana, sold under the name Zonolite.

Why is vermiculite bad?

Nearly all vermiculite contains asbestos, which can cause lung cancer when inhaled. While it’s true that undisturbed, encapsulated asbestos doesn’t pose a health risk, the asbestos in vermiculite insulation isn’t encapsulated and can easily become airborne during cleaning, maintenance or remodeling. And, the type of asbestos found in vermiculite—called amphibole—is even more hazardous than the chrysotile asbestos that was more commonly used in the U.S.

Federal guidelines are weak

The EPA (Environmental Protection Agency) recommends that if you have vermiculite, it’s best to assume it contains asbestos and leave it alone. You can have it tested for asbestos, but here’s the rub. The EPA defines an asbestos-containing material (ACM) as having greater than 1 percent asbestos. If it’s found to contain less than 1 percent asbestos, it’s not considered an ACM. That’s misleading, as it seems to imply that the product is safe. But, as part of a major class-action lawsuit, a study determined that exposure to vermiculite with less than 1 percent asbestos is still a potential health hazard and the product should be considered an ACM.

What to do if you have vermiculite in your home

Contact an insulation contractor. In Minne­sota, where I live, an insulation contractor’s first step is having the insulation tested for asbestos. The vast majority of tests come back having less than 1 percent asbestos. That means no asbestos abatement contractors get involved, and removal of the vermiculite insulation is done with essentially a giant vacuum. The risk of airborne particles in this method is high. And according to the Zonolite Attic Insulation Trust (see “The good news” below), the presence of vermiculite is tantamount to the presence of asbestos. For this reason, I recom­­mend having this work done by asbestos abatement professionals regardless of the test results.

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The good news

The Zonolite Attic Insulation Trust was established in 2014 to help homeowners with the cost of removing Zonolite Attic Insulation from their homes. The trust reimburses homeowners for 55 percent of their removal and reinsulation costs, with a maximum payout per owner of $4,125. So, if you have vermiculite insulation, look into this. In the meantime, leave it alone, even if you had it tested and the test came back “clean.”
For more information, visit zonoliteatticinsulation.com.

Meet the expert

Reuben Saltzman has been a home inspector since 1997 and is the president of Structure Tech, a home inspection company in St. Louis Park, MN.

Next, read: How to Improve Attic Ventilation.