For more than 80 years, roofing felt was used in the roofing of many different business and residential structures. As was the case with a large number of building materials manufactured between 1900 and the 1990s, most roofing felt contained asbestos fibers in order to give it greater tensile strength as well as fire resistance. This roofing felt, which usually also contained asphalt, was mostly employed in structures with flat roofs but can be found in more traditional pitched roofs as well.
Asbestos roofing felt generally contained between ten and fifteen percent asbestos by volume. This asbestos was generally of the chrysotile, or common “white” variety usually found in the serpentine rocks of western Montana , California , and Quebec , where it is still commercially mined. Once the health dangers of asbestos became widely known starting in the 1980s, U.S. manufacturers began phasing out the use of asbestos in roofing felt and other building materials. Nonetheless, it is still commonly found in large numbers of homes throughout the country.
If you encounter asbestos roofing felt in your own home, there is no immediate cause for worry. If the roof of your home is in good condition, chances are that any asbestos-containing products present are not in a “friable” state – which is to say that they are not in a condition in which they are crumbling into dust and spreading asbestos fibers into the atmosphere. However, vapor barriers that are made from chemically-impregnated paper are considered to be friable, and can easily cause the release of fibers if cut, drilled, sawed or ground.
If your roof is in good condition, the best course of action is to leave it be. If you are working on a roof and do not know when it was last repaired or replaced, the safest course of action is to assume that the roofing felt and other materials contain asbestos fibers.
Most states allow homeowners to remove asbestos containing materials from their own property provided that it is their primary residence. Landlords engaged in renovation of rental property are subject to all state and federal laws and EPA regulations pertaining to asbestos abatement; however, any asbestos-containing materials that are to be removed from said property must be contained in plastic bags no less than 6mm thick, sealed with duct tape, and clearly labeled before being taken to an approved toxic waste facility.