Asbestos Products
Asbestos products are unlike other construction materials because, aside from exposure during manufacturing, they often become hazardous only when they begin to degrade. These materials were widely used during the Industrial Revolution as insulating material for high temperature applications, such as boilers, ovens, kilns, steam piping, etc.
The use of asbestos products peaked between 1950 and 1975. During this time period, thousands of miles of asbestos cement pipe were laid throughout the United States for drinking water distribution, and many of those conduits remain in use today. Asbestos cement pipes have an estimated lifespan of 70 years, but could last much longer under favourable conditions. They are frequently encountered in rural areas and in agricultural applications. When in use, asbestos cement pipe poses few health issues. However, when the pipe fails and must be removed and replaced, workers can be exposed to airborne asbestos fibres in dust particles.
Asbestos products were often used as insulating materials. Manufacturers supplied large, woven sheets of asbestos that end-users wrapped around piping, boilers, ovens and kilns as thermal insulation. Asbestos insulation was a very desirable material at the time because the fibres were very pliable and easy to work with, and the material was inflammable and resistant to many chemicals. Asbestos products could also be applied as a spray to insulate or fireproof structures. They were even widely used in the automotive industry to coat brake linings, clutch pads, and other mechanical parts where friction was expected to create heat.
In construction applications, contractors used asbestos products both inside and outside of commercial and residential buildings. For example, exterior asbestos products included asbestos cement corrugated roofing panels, roofing felts, roofing shingles, soffits, siding panels, asphalts and mastic paints. Interior vinyl floor tiles and sheet vinyl flooring were commonly constructed with asbestos products or used an asbestos paper backing. Uneven floors were levelled with an asbestos compound. Asbestos products were used in ceiling tiles, drywall joining materials, stucco coatings and acoustic finishes. It was the preferred insulation on old wiring was blown into wall cavities as loose fill insulation.
When dry materials that contain asbestos can be crushed into a powder by hand, they are said to be “friable.” Ceiling tiles, drywall joining materials, stucco coatings, and sprayed-on pipe insulation are friable materials. Roofing shingles, vinyl asbestos floor tiles and asbestos cement sidings are non-friable materials because they cannot be crushed by hand. When remodelling, demolition or burning occurs, however, these materials can become friable.