ASK THE INSPECTOR: Attic asbestos insulation best left alone

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This article was published 07/12/2013 (4290 days ago), so information in it may no longer be current.

QUESTION: I live in a two- storey home in River Heights, built in 1965. The attic entrance is in a bedroom, which has been converted into an office and is used many hours of the day. I have no idea if there is asbestos in the insulation, but I was wondering if the air in the office could be tested for asbestos. The entrance to the attic is covered but not sealed, and no one has been in the attic for about five years.

Thank you very much for your help, and I enjoy your column in the Free Press.

Arthur Cohen

ANSWER: While I commend you on your proactive attitude toward testing for a potential health or safety hazard in your home, in this case, that may not be prudent. In most homes, any asbestos that may be hidden in your relatively well-sealed attic should be treated as in the old cliché: out of sight, out of mind. This may seem like an irresponsible recommendation for me to be making, but in relation to asbestos-containing insulation in attics, it is best left undisturbed.

In most Canadian homes there is only one type of insulation that was widely used that is known to contain significant amounts of asbestos. That insulation is a specific brand of vermiculite, which is made by heat expansion of a type of mineral, which is similar to mica. The brand that is known to contain asbestos fibres is Zonolite, manufactured from vermiculite ore that was previously mined at a site in Montana. While Zonolite was produced for many decades from this source, it was not until the 1980s that the presence of asbestos fibres was discovered or disclosed. By that time, thousands of homes in North America had vermiculite insulation installed. In most cases, this fireproof insulation was only installed by pouring the material from bags into attics. In rare cases, it was also poured into hollow wall cavities, but that was not very popular due to the difficulty in installation relative to other types of batt insulation.

The problem with Zonolite occurs when the material deteriorates over time. This is primarily a natural process due the composition of expanded vermiculite, which contains several types of compounds. When this deterioration occurs, some embedded compounds can be released, including asbestos fibres. One thing that significantly accelerates this rate of deterioration is disturbing, moving, crushing or stirring the vermiculite insulation. For this reason, the less an attic containing vermiculite is entered or worked in, the better. That is the main rationale for my earlier recommendation to leave well enough alone.

Because vermiculite was installed in many homes at a time when much lower insulation levels were considered adequate, numerous homeowners have added more thermal insulation in subsequent years. This newer insulation is normally composed of fibreglass batts, but also may include blown-in cellulose, loose fibreglass or other products. This newer insulation is almost always blown or laid directly on top of the older vermiculite, which has numerous benefits. First, the increased insulation may completely cover any exposed vermiculite, preventing deterioration from air movement or wind currents within the attic due to typical ventilation. Secondly, the weight of the new layers of insulation will significantly restrict movement of the vermiculite, preventing deterioration and asbestos-fibre friability. Finally, the newer blanket of material will help protect against damage or disturbance of the vermiculite should anyone enter or work in the attic.

Returning to your original question, testing the air in your office or home may yield no significant results, even if you have asbestos-containing Zonolite in your attic. Because nobody has opened or entered your attic for several years, there is almost no chance any asbestos has penetrated your living space. Any indoor air testing that is looking for asbestos will come out negative whether your attic is full of Zonolite or has none. The only true way of determining any potential risk is to remove the attic hatch, look to see if there is any visible or covered vermiculite, then collect a sample and send it to a laboratory for testing. To accomplish this, you will have to risk potential exposure of your office to asbestos contamination,where none currently exists.

It is true that other building materials in your home, such as vinyl flooring, cement boards, boiler pipe, forced-air duct wraps and even some finishing materials may contain asbestos. These are also of minimal concern if not damaged. Many of these products have fibres embedded well within other components, which may only be released when they are sanded, scraped, cut or otherwise manipulated during removal or renovation. The only major exceptions to this are asbestos coatings and wraps used on older boilers and heating pipes, which can become friable over time due to heat and deterioration. Due to the age of your home, it should not have an older hydronic heating system with asbestos on the pipes or boiler. For those that do fall into that category, they should be frequently inspecting the heating system so any loose or damaged insulation can be encapsulated to prevent release of fibres into the air.

The recommendation by Health Canada, CMHC and other knowledgeable authorities in relation to vermiculite installed in attics is to leave it alone. If it does have to be disturbed due to repairs or renovations, all possible precautions should be taken to prevent contamination of the living space with any loose asbestos fibres. As far as testing your indoor air for asbestos contamination, unless you have visible asbestos insulation on your hot-water heating system, there should be no need to test or worry.

Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and president of the Canadian Association of Home & Property Inspectors – Manitoba (www.cahpi.mb.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at www.trainedeye.ca.

trainedeye@iname.com