A while back I posted a blog on Environmental Concerns and gave a brief history on the use of asbestos in various products over the years. In the examples given, asbestos was purposely used to improve product performance. We all know the consequences of prolonged asbestos exposure. If you are unaware of the health concerns please visit Asbestos Exposure and Cancer.
During a recent inspection I saw what I believe to be Vermiculite insulation in an attic. I've inspected a few homes with this type of insulation before so I wasn't surprised to find it but I do know it's something that is a concern to the buyer. Anytime you say there's a potential for asbestos in a home people get nervous. I never make light of the possible consequences of exposure to potentially contaminated products but I also believe it's important to educate the buyer so they know what to expect.
Vermiculite is actually a naturally occurring mineral similar to mica that was largely mined in Montana. When exposed to heat vermiculite expands, think popcorn, into a light-weight and fire-resistant material to be used in various products including attic insulation. Vermiculite has an R value of about 2.1 per square inch. Current standards in my area call for about an R48 so you would need a substantial amount of vermiculite to meet that recommendation. In the photo above you can see the vermiculite is mostly covered by an R19 fiberglass insulation.
The concern with having vermiculite insulation in the attic is the potential for contamination with asbestos fibers. Between 1919 and 1990 approximately 70% of vermiculite was mined in Libby, Montana which also happened to contain a deposit of asbestos. This insulation was often sold under the brand name Zonolite. Zonolite was manufactured and installed in U.S. homes from 1963 until around1984. The Census Bureau estimates approximately 35 million homes were built from 1963 through 1984. Estimates of the number of houses with Zonolite insulation range from 12 million to 35 million. When I find vermiculite insulation my recommendation is as follows:
The attic contains what appears to be vermiculite insulation. Not all vermiculite insulation contains asbestos but prior to its close in 1990, much of the world’s supply of vermiculite came from a mine near Libby, Montana. This mine had a natural deposit of asbestos which resulted in the vermiculite being contaminated with asbestos. Attic insulation produced using vermiculite ore, particularly ore that originated from the Libby mine, may contain asbestos fibers. Recommend that homeowners make every effort not to disturb vermiculite insulation in their attics. If you occasionally have to go into your attic, current best practices state you should:
1. Make every effort to stay on the floored part of your attic and to not disturb the insulation.
2. If you must perform activities that may disturb the attic insulation such as moving boxes (or other materials), do so as gently as possible to minimize the disturbance.
3. Leave the attic immediately after the disturbance.
4. If you need work done in your attic such as the installation of cable or utility lines, hire trained and certified professionals who can safely do the work.
5. It is possible that vermiculite attic insulation can sift through cracks in the ceiling, around light fixtures, or around ceiling fans. You can prevent this by sealing the cracks and holes that insulation could pass through.
6. Common dust masks are not effective against asbestos fibers. For more information regarding the risks of asbestos check out the download to the right (Vermiculite Insulation), or the EPA’s website at http://www.epa.gov/asbestos. The EPA also has a free printable brochure on vermiculite insulation that can be downloaded here.
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