Dangers of Asbestos Contaminated Vermiculite Insulation in Your Home

Vermiculite insulation between floor joists in attic.
Vermiculite insulation between floor joists in attic.*

Vermiculite is a popular insulation material, but much of the vermiculite used in the U.S. during the 20th century was contaminated with asbestos. Removal of vermiculite insulation can be costly and complicated; but in some cases, you may be able to leave the material in place with proper precautions.

If your home or office has vermiculite insulation, here’s what you need to know to protect yourself from exposure to dangerous asbestos.

The Vermiculite/Asbestos Connection

Vermiculite is a natural flaky mineral (similar to mica) that expands like popcorn when heated. Vermiculite is used in insulation, fire retardants, cement aggregate, fertilizer, and potting soil. The most popular vermiculite insulation in the U.S. was sold under the brand name Zonolite by W.R. Grace & Co.

Vermiculite insulation granules
Vermiculite insulation granules.*

Until 1990, most of the vermiculite sold in the U.S. came from a mine near Libby, Montana, that contained a deposit of asbestos which contaminated the vermiculite.

Asbestos is a mineral fiber that can easily become airborne and causes serious lung diseases such as asbestosis, mesothelioma, and other types of lung cancer. It only takes being exposed to asbestos one time to get mesothelioma and other lung diseases. Some of these illnesses can take 20-40 years to show symptoms after exposure. Visit the Mesothelioma Cancer Alliance website for more information.

The Libby mine was closed in 1990, but not before contaminated vermiculite insulation made its way into millions of homes and buildings. The problem is so widespread that the EPA recommends that all vermiculite insulation should be assumed to be contaminated with asbestos.

Indentifying Vermiculite Insulation

Vermiculite insulation is pretty easy to identify. It’s pebbly and loose and resembles very lightweight gravel or small packing peanuts. Most other types of insulation are fibrous or woolly.

Vermiculite insulation may be poured inside framed walls or cinder (concrete) block walls, as well as spread out between attic rafters or under floors.

How to Deal with Vermiculite Insulation

If you find vermiculite insulation in your home, the most important step is not to disturb it. Asbestos is only a danger if it becomes airborne. Sometimes the best solution is to leave the insulation in place, and take steps to protect your home against any airborne asbestos particles.

In dealing with existing vermiculite insulation in your home:

    Vermiculite insulation granules next to paper clip for scale
    Vermiculite insulation granules.*
  • Assume Asbestos Contamination: There’s no firm cut off date for asbestos contaminated insulation; so to be safe, treat all vermiculite insulation as if it contains asbestos. Testing is expensive and inaccurate, and the probability of asbestos contamination is so great, that the EPA recommends erring on the side of caution rather than testing for asbestos.
  • Do Not Disturb Vermiculite: Never stir, handle, or move vermiculite insulation, or do anything to it that might create dust. Even small movements can send asbestos particles into the air. If the asbestos is undisturbed, and it’s sealed away from your home’s living space (such as in a ventilated attic or inside the walls), many homeowners decide to leave vermiculite insulation alone, rather than spending thousands of dollars on remediation.
  • Professional Asbestos Removal Contractor: If you’re doing remodeling that will stir up vermiculite insulation or you want to remediate the building, be sure to hire a professional asbestos removal contractor. Professional negative pressure systems can protect your living space from air contamination during the removal process. At the very least, have someone inspect your home to make recommendations for encapsulating the insulation and preventing leakage.
  • Vermiculite insulation granules
    Vermiculite insulation granules.*
  • Keep Out of Contaminated Areas: Don’t store anything in attics insulated with vermiculite, and make the area is off limits.
  • Seal Off Vermiculite Insulation: Make sure any area containing vermiculite insulation is sealed off from the interior of your home. Use caulk or spray foam around seams, light fixtures, fans, and switches, as well as plumbing pipes or other openings where insulation dust might filter in. Hire an asbestos contractor to install attic flooring that completely covers and seals off the insulation.
  • Warn Workers About Vermiculite Insulation: Talk with anyone working on your home to make sure they understand the risks of working around vermiculite insulation. Special precautions should be taken before cutting a hole in the walls or ceilings if the vermiculite insulation might be disturbed. You may also want to put up signs in the attic, as a warning to workers who may disturb the insulation by accident.
  • Wear Protection Around Vermiculite Insulation: If you must be exposed to the insulation for even short periods of time, wear goggles and a HEPA respirator (not just a dust mask). Walk only on the floored part of the attic, and don’t touch or disturb the vermiculite particles. Clean up small amounts of dust with a wet cloth or HEPA filtered vacuum. However, remember that it’s much better not to have ANY contact with vermiculite insulation!

*Photos from the Environmental Protection Agency.

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