The risk of exposure to asbestos depends on several factors. The condition of the material, type of disturbances, and the material’s friability play a large role in this. However, it could be argued that friability is the greatest factor. Friability refers to whether or not a material can be ground into a powder with hand pressure when dry. Once a friable asbestos-containing material turns into a powder, it is more likely that the fibers may be released and become airborne. In this blog we will discuss examples of friability.
Friable TSI & Surfacing Materials
Examples of friable asbestos-containing materials are often found in the thermal system insulation (TSI) and surfacing material classes. TSI would include the insulation used around water pipes, ductwork, and boilers. Materials such as thermal insulation often contain asbestos-laced paper, such as air cell pipe insulation or in a composite like magnesia block. These materials typically have a high asbestos concentration and can be rendered to a powder fairly easily. This is why it is imperative to repair or abate damaged thermal system insulation.
Surfacing materials are materials that are sprayed or troweled on to surfaces. Examples of surfacing materials include popcorn ceiling, plasters, spray- on fireproofing, among others. Surfacing materials are classified as high risk materials and nearly all of their application methods can render the materials friable.
There are also friable materials in the “miscellaneous” asbestos category. This category refers to all other asbestos containing materials that are neither thermal system insulation nor surfacing materials. Common friable materials that are miscellaneous are drywall, drywall joint compound, and ceiling tiles. While drywall can be asbestos-containing, it is most likely to be contained within the drywall joint compound. The asbestos concentrations of these materials are likely to have lower concentrations than TSI or surfacing materials but are still hazardous if disturbed, as there is no safe exposure for asbestos. Ceiling tiles that are asbestos containing are also considered to be friable.
There are also asbestos-containing materials that are non-friable, meaning they cannot be rendered friable with hand pressure under certain conditions. The most common example of this is vinyl floor tile. Asbestos-containing vinyl flooring is a mixture of organic binder with asbestos fibers ranging from 1 to 10% in concentration. Since the asbestos fibers are encapsulated in the binder, it makes it difficult for fibers to be released. Another example is floor tile adhesive, also known as mastic. Floor tile adhesive is typically composed mostly of binder, similarly to floor tile, with the asbestos ranges commonly in the 1 to 5% range. Other non-friable materials such as transite and galbestos are considered to have some of the highest asbestos concentrations and can exceed that of many thermal system insulations and surfacing materials.
While non-friable materials are generally unlikely to release asbestos fibers easily, in some cases these materials can be rendered friable. One way that this occurs is excessive wear on the materials from exterior weathering or contact, for example aged transite. Another way is through damage by mechanical means, such as scraping or nailing into vinyl floor tile — which may damage the binder enough to release fibers. Another common example is inexperienced contractors sanding or grinding asbestos-containing mastic off flooring,
Managing non-friable materials is generally easier than with friable materials, due to their ability to hold on to their fibers more effectively. Thus non-friable materials are considered to be lower risk than friable materials. In some cases under federal demolition guidelines such as NESHAP, certain non-friables such as floor tile can remain in a property during demolition if the material will not be rendered friable during those activities. Before disturbing asbestos materials regardless of friability, it is imperative that the material be tested by a professional such as Indoor Science.