While performing Home Inspections and Energy Audits in the Reno area I do come across Vermiculite insulation on occasion. Vermiculite insulation around here is usually found in the attics of older homes. Vermiculite was sold in bags which made it easy to pour into the attic, even by home owners. It’s R Value is about R-2 per inch.
Used for many different purposes it is a naturally occurring material that is mined. The large majority of the Vermiculite came from the Libby Mine in Montana until the mine closed in 1990. The EPA states that unless it is tested you should always treat Vermiculite as if it does contain asbestos. The EPA doesn’t recommend its removal and it is thought to be low risk as long as it's not messed with since it’s in the attic which is ventilated. Do not disturb Vermiculite. Some suggest posting signs in the attic saying "Cancer Hazard: Insulation contains asbestos, do not disturb or create dust."
During a Home Inspection or an Energy Audit it is important to look for and inform people of its presence. While it is not considered to be a great hazard it could make remodeling more difficult. During a recent Energy Audit I discovered the presence of Vermiculite in the attic. The owners of the home were unaware it was in the attic and it was not identified during the Home Inspection. Because other work was needed in the house they obtained a quote for the removal. The cost was in the 10K range for about 1500 sqft.
During the years Vermiculite often gets covered up by other insulation so it’s best to dig a little to see. If you suspect Vermiculite in your attic get it looked at by someone that knows what it looks like. If confirmation of asbestos is needed get it tested by a lab. For more information take a look at the EPA site http://www.epa.gov/asbestos/vermiculite.html