Vermiculite Insulation

En Español (Spanish): Aislantes de vermiculita (PDF: 46KB/1 page)


Vermiculite is a naturally occurring mineral compound that expands when wet. A member of the phyllosilicate group of minerals, it resembles mica in appearance. In its pure form, vermiculite is clean, odorless, nontoxic and sterile. Recent findings about vermiculite ore contaminated with tremolite asbestos have caused concern over possible health effects for workers and others who had long-term contact.

Vermiculite insulation in an attic.

Vermiculite insulation

Click images to enlarge.

How does asbestos cause health problems?

For asbestos to cause harmful health effects, it must be present as a tiny fiber that could be inhaled or ingested. When disturbed, asbestos breaks down into fibers 1,200 times thinner than a human hair. If these fibers are inhaled, they become trapped in lung tissue or in tissue lining the lungs and cause scarring. Asbestos fibers can cause respiratory system and lung diseases, including cancer. There is no known safe level of asbestos exposure.

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How do I know if there is vermiculite insulation in my home?

Vermiculite attic insulation is a pebble-like, pour-in product and is usually light-brown, gray, or gold in color. It may have shiny flakes, and/or small accordion-like pieces (see photos above). You can also check for markings on the material or its packaging. One common brand was called Zonolite.

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What should I do if I have vermiculite attic insulation?

Leave it alone. If vermiculite insulation is disturbed, it may release asbestos fibers into the air. At this point the safest and easiest option for intact insulation is to leave it alone. If the insulation is exposed or spilling into living areas, immediate steps should be taken to seal the cracks. Although Minnesota law permits homeowners to remove small quantities of asbestos-containing material, the Minnesota Department of Health strongly recommends using a Minnesota-licensed asbestos contractor for the protection of your family's health. These contractors have access to removal and encapsulation (trapping) techniques unavailable to homeowners. They will also perform air monitoring to determine if the indoor air meets acceptable standards at the completion of the project.

Who can I contact for more information?

For more information, please contact the Site Assessment and Consultation Unit: Contact Us

Links —


Current best practices for Vermiculite Attic Insulation- May 2003 (PDF: 586KB/2 pages)

En Español (Spanish): Las mejores prácticas actuales para el uso de vermiculita en el desván (PDF: 123KB/2 pages)

EPA - Asbestos

ATSDR - Vermiculite Consumer Products

This information sheet was prepared in cooperation with the Agency for Toxic Substances and Disease Registry.

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Updated Friday, 16-Sep-2011 15:33:01 CDT