Question Box: What Is Vermiculite Insulation & Was It Used In Calgary Homes?

If you’re thinking of purchasing a home in Calgary built before ~1990, it would be prudent to take an additional step of determining what type of insulation was used.   Of concern is a certain type of vermiculite insulation that even had a processing plant here in Calgary.

From Health Canada: Vermiculite is a naturally occurring mineral mined around the world and has been used for insulation and agricultural purposes.  However Health Canada has found some brands of vermiculite insulation may contain tremolite asbestos and could present a health hazard.


Some vermiculite produced at Libby Mine in Montana from the 1920s until 1990, sold primarily under the brand name Zonolite®, has been found to contain asbestos. While not all vermiculite produced before 1990 contains asbestos fibres, it is reasonable to assume that if a building has older vermiculite-based insulation, it may contain some asbestos.

Since most of the vermiculite used in Canada was taken from the Libby mine, the odds are quite good that there is asbestos in the vermiculite in Canadian attics – including here in Calgary.

Did you know? In western Canada, plants processing Zonolite were operating in Winnipeg, Regina, Edmonton, Calgary, and Vancouver.
CBC The National

Use of this type of deadly insulation was spurred onward because it made the list of eligible materials for the federal government’s Canadian Home Insulation Program (CHIP), a program that offered grants to homeowners from 1977 to the mid-1980s.

Health Canada – Minimizing Your Risk

The best way to minimize your risk of amphibole asbestos exposure is to avoid disturbing vermiculite-based insulation in any way. If vermiculite-based insulation is contained and not exposed to the home or interior environment, it poses very little risk.

If you are concerned that your home may contain vermiculite-based insulation visit the Need More Info? section in this article or the Health Canada Web site to get the most up-to-date information as it becomes available.

If you know you have vermiculite-based insulation in your attic, take these precautionary steps.

  • Do not allow children to play in an attic with open areas of vermiculite-based insulation and make sure anyone working in the attic knows about the possible presence of amphibole asbestos.
  • Do not use the attic for storage if retrieving items from it may disturb the insulation.
  • If you must go into the attic, walk on boards in order to minimize disturbance of the insulation and use an appropriate respirator mask. Do not remain in the attic any longer than is necessary.
  • Common dust masks are not effective against asbestos fibres.
  • If you have vermiculite-based insulation and you decide to have it removed, speak to trained and qualified asbestos removal professionals to handle the insulation removal. They can be found by looking up experts in “asbestos abatement removal.”  NEVER attempt to remove the insulation yourself.
  • If you plan to remodel or renovate–for instance, by re-insulating your attic–in a manner that would disturb the vermiculite, speak to professionals who are trained and qualified to handle asbestos removal before proceeding with the work to be done.
  • Seal all cracks and holes in the ceilings of the rooms below the insulation (for example, apply caulking around light fixtures and the attic hatch) to prevent insulation sifting through.
  • If you suspect you have vermiculite-based insulation in your walls, as a precautionary step, seal all cracks and holes. For example, apply caulking around window and door frames, along baseboards and around electrical outlets.

Sources for additional reading

2 responses to “Question Box: What Is Vermiculite Insulation & Was It Used In Calgary Homes?

  1. lauren jonczak

    Great post. I have been doing a little research on attic insulation because I just found out that I have to redo mine do to squirrels. I have never heard of Vermiculite insulation before. I did know that some insulation can be harmful and that is exactly what I am trying to avoid. Thanks for the great information.

  2. Great post! Lots of homeowners and buyers are unaware of this hidden danger that can be found in your attic.

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