Evan Renwick, P.E., Senior Engineer
Atlantic Testing Laboratories

Vermiculite was used throughout the 20th century in construction materials, including as loose-fill insulation for commercial buildings and residential homes. It was also commonly used as a potting soil additive. Vermiculite is not an asbestos mineral, but when mined in places like Libby, Montana, it became contaminated with tremolite asbestos deposits located within the vermiculite mines. As a result, loose-fill vermiculite, known commercially as Zonolite, is considered a Presumed Asbestos-Containing Material in the State of New York.

Vermiculite used in wall cavity (above) and floor (below)

 When loose-fill vermiculite is installed, asbestos fibers settle toward the bottom over time due to gravity. If a sample of settled material was analyzed, it would not be representative of the asbestos content of the loose-fill vermiculite. Therefore, there is no approved laboratory analysis method for loose-fill vermiculite in New York State. For that reason, if loose-fill vermiculite is encountered during an asbestos survey in New York State, it must be quantified and assumed to contain asbestos.

Loose-fill vermiculite is typically found in attics and wall cavities where it was placed as insulation. Walls constructed with concrete masonry units (CMU) were commonly insulated with loose-fill vermiculite. Because CMU wall cavities are not typically exposed to view during an asbestos survey, caution should be exercised when impacting these walls during renovation/ demolition projects. It is recommended to confirm that loose-fill vermiculite does not exist in CMU wall cavities prior to impacting these walls. If a CMU wall is impacted, and loose-fill vermiculite is released, the area should be evacuated immediately, and an Incidental Disturbance Assessment performed to determine the extent of contamination.

Atlantic Testing Laboratories, a WBE Certified Company, provides Asbestos Inspection, Incidental Disturbance Assessment, Asbestos Abatement Design, and Asbestos Abatement Project Monitoring Services throughout New York State.

For more information, contact Evan Renwick, P.E., at 315-386-4578 or Erenwick@atlantictesting.com.


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