Vermiculite, Zonolite & Asbestos
Vermiculite is a naturally occurring mineral used for several decades as building insulation because it is lightweight and fire resistant with good acoustic performance. The majority of vermiculite was mined in Libby, MT between the 1940’s and 1990’s and marketed under the brand name Zonolite. It’s estimated that 35 million U.S. buildings may have Zonolite insulation.

What’s the Real Problem?

Most of the vermiculite used for Zonolite was found to be contaminated with asbestos from a nearby mine. In fact, some samples contained tremolite asbestos which is up to10 times more carcinogenic than the more common chrysolite asbestos. Exposure to contaminated Zonolite increases the risk of life threatening diseases such as mesothelioma, lung cancer and asbestosis.

The Montana vermiculite mine is now a Superfund site with more than $120 million spent on cleanup so far. The mining company was subject to lawsuits from miners, people who worked in Zonolite manufacturing, and the occupants of contaminated buildings.

Solving the Problem with science

If you suspect that your home has vermiculite, DO NOT disturb it! And, DO NOT PERFORM A DEPRESSURIZATION BLOWER DOOR TEST. This would draw air through the contaminated insulation and possibly send asbestos fibers into the living areas.    

Assume it contains asbestos until proven otherwise. Even collecting samples yourself can expose you or loved ones to harmful fibers. The best course of action is to contact an asbestos abatement expert who can identify asbestos and remove it safely. While the process can be involved and expensive, you may be able to receive some compensation. The Zonolite Trust website is a good resource for testing, abatement and possible financial assistance.

Once the contaminated insulation is removed, you can contact a certified Energy Professional to learn about current best practices for air sealing and insulating your home. 

Next steps

  1. Read information at the Zonolite Trust to get general information on Vermiculite, asbestos, and the process necessary to get assistance in testing and abating.
  2. Contact a local Asbestos Abatement professional
  3. Find a certified Energy Professional to discuss opportunities for performance improvements that would be well suited to incorporate with said situation.

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