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Asbestos is common in chimneys, furnaces, and wood stoves in homes and other buildings constructed before 1980 because of its abundant use in construction materials in past decades.[1] Asbestos resists fire and heat, making it useful for insulation in stoves and furnaces.[2] Originally used to make homes safer, these materials may release asbestos fibers and cause harmful exposure.

Many chimney flues, exhaust pipes from fireplaces contained a material called transite.[3] This was a brand of asbestos-containing cement material created by Johns Manville.

Transite was originally a brand name; however, the term became a common word for any similar material. Originally, transite was made with cement mixed with 10 to 50% asbestos. Asbestos in transite was phased out by 1980.

Homes built before 1980 are likely to contain transite with asbestos, most often in chimney flues—the material lined chimney flues in commercial buildings and residential homes. The purpose of the flue lining is to resist fire and keep heat from escaping.

Chimney flues were not the only flues that used transite with asbestos, however. Any venting flue, even connected to water heaters, furnaces, and other appliances, may contain asbestos, especially in older homes.[3]

Asbestos is no longer used in chimneys and other venting flues; however, it may still be present in older homes. Renovation or construction work on the chimney and flue can expose asbestos, sending fibers into the air.

Even without renovation work, asbestos in older flues can harm residents. The lining material of the flue may deteriorate over time, causing blockages that in turn cause exhaust gases, along with asbestos fibers, to vent back into the home.

Furnaces are also a potential source of asbestos in older heating systems. It is not just the venting flue that may contain this material. Several types of material containing asbestos were used to insulate furnaces and protect surrounding walls. These materials include:

Furnace gaskets also contained asbestos before 1980. Gaskets are rings that connect two materials to prevent leaks. Furnace gaskets used asbestos to prevent heat from leaking out.

The doors of furnaces were often lined with asbestos materials. Vents and ducts leading to and from furnaces may also have been insulated with asbestos.

Asbestos materials can be dangerous today because heat from the furnace can cause asbestos to become friable over time. Friable means the asbestos can easily crumble, causing fibers to become airborne. Since friable asbestos is particularly dangerous, it should be removed by a trained asbestos abatement professional.[4]

Another asbestos source in heating systems of older homes is the wood-burning stove. In addition to ducts and the flue used to vent gases, asbestos may be found in components of the stove itself.

It may also be found in insulating material around it. Also, a wood stove may have millboard, cement sheet, or asbestos paper and tape for insulating and fireproofing.[2]

Older stoves may also have asbestos in door gaskets. Wood-burning stoves with cook-top surfaces may contain asbestos in their pads and trivets.

The heat of the stove can cause insulating asbestos to become friable; therefore, asbestos-containing wood stoves should be inspected and abated by trained asbestos professionals.

For the layperson, identifying asbestos is problematic and potentially dangerous. Determining whether or not you have asbestos materials in your chimney flue, furnace, or wood stove is a task best left to trained professionals. Every state has its own licensing and training requirements for asbestos professionals, so check for a local professional.

Finding asbestos in your heating systems does not mean your family is in imminent danger. Well-contained asbestos that has not become friable poses no real risk; however, if you have a professional inspect your home and finds friable asbestos, you will need to have it abated.

Abatement does not necessarily mean removal. Whether it is most practical to remove the asbestos depends on the asbestos type of asbestos and its condition.

Your professional can determine if removal is the best option. The alternative is asbestos containment. If containment is the route you take, be sure to have it regularly inspected for damage or deterioration.[5]

Asbestos can cause many worries, especially if it is in and around the elements that heat your home and vent gases. With a professional’s inspection and abatement, asbestos materials should not pose a significant health hazard. If you are unsure if your heating components contain asbestos, have them checked by a licensed professional. This is particularly important if you plan renovations or repairs. Having the inspection done first is crucial and could prevent your family from being exposed to harmful asbestos fibers.

Dave has been a mesothelioma Patient Advocate for over 10 years. He consistently attends all major national and international mesothelioma meetings. In doing so, he is able to stay on top of the latest treatments, clinical trials, and research results. He also personally meets with mesothelioma patients and their families and connects them with the best medical specialists and legal representatives available.