Is it possible to paint asbestos siding?
Your question is very timely, but not in the way you may think. We have heard and will be hearing a great deal about asbestos in homes lately, due to the recent discovery of asbestos content in some types of Vermiculite insulation. I am going to diverge completely from your concern and will expand on this further, but first I will answer your question, directly.
Yes, painting asbestos cement siding is not only possible, it is recommended. The reason is that it will prevent deterioration, which may cause some of the asbestos fibres to become friable and get into the air outside the home. Painting or encapsulation of products known to contain asbestos is an acceptable way to prevent any possible health concerns. Asbestos cement siding poses very minimal, if any, health risk, due to the nature of the asbestos fibres that are fully embedded in cement. This will minimize the possibility that they will become loose or friable, unless the siding is damaged.
This type of siding is very durable, but is also brittle and may be subject to damage. Special care must be taken when painting the siding to avoid breaking the individual tiles, as well one other particular precaution. This material should never be sanded or scraped, as this may release asbestos fibres into the air, where they can be breathed in by the individual working on the renovations. Dust masks or respirators should be worn when working on the home, if the material is deteriorated or needs excessive cleaning.
As with all building materials, especially exterior products, the key to a good paint job is preparation before finish coating. Proper cleaning should be done before painting the siding with the appropriate primer, which must be fully dry before the finish coat is applied. Contact the paint supplier where the finish paint is purchased for the appropriate primer that will be compatible. Pre-tinting the primer may help with the coverage and appearance of the final product.
Asbestos has been used in building products such as insulation, flooring, and siding for many years due to its strength and fire resistant properties. It has been phased out of many of these materials during the last 25 years due to the health risks involved. Many older homes still contain insulation, flooring, siding, fireplaces and other materials that have some asbestos content. These building materials pose little risk if the fibres are encapsulated or embedded in the material, such as the siding mentioned or vinyl asbestos floor tiles. These products only pose a potential health risk if the fibres become loose or friable and become airborne.
Diseases related to asbestos, such as certain types of cancer and Asbestosis, may be fatal to people who have had long-term exposure to the material. There are many cases of disease and deaths in industrial and commercial situations, but little evidence of any illness from residential situations. Most of the evidence in these cases is anecdotal and don’t have proven direct links to building materials within the home. Regardless, care must always be taken when working near or handling materials that are know to have some asbestos content. Protective breathing apparatus, goggles and protective clothing should be worn to prevent inhaling the fibres.
The recent revelations about Vermiculite insulation produced with minerals from one mine, under the Zonolite brand name, having a possible asbestos content has brought this issue back into the forefront. This insulation has not been sold in Canada for over 20 years, but may still be present in many older homes. Health Canada has recently produced a document entitled “Vermiculite Insulation Containing Asbestos”. In this document they state that, “The best way to minimize your risk of 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”. Most of this insulation was installed in attics, away from the living space, but may also be present in walls or concrete block within homes.
There is a tendency for the media and other institutions to initially overreact when new information on possible health concerns, such as this recent case, arises. The key to proper precautions and concerns is education on the subject. Any homeowner who has this type of insulation in their home, and is planning renovations, should obtain further information from reputable sources such as Heath Canada, Natural Resources Canada, the Canadian Mortgage and Housing Corporation (CMHC) or the U. S. Environmental Protection Agency (EPA). All these sources have excellent information on their websites.
The Health Canada article cited can be found on their website at: http://www.hc-sc.gc.ca/english/iyh/products/insulation.php.