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Asbestos Surfacing Materials

Plaster on Lathe

Have you ever seen a popcorn ceiling in a property built before 1980? It is possible that this material is an asbestos-containing surfacing material. Asbestos-containing surfacing materials are materials that are sprayed or trowelled on surfaces. Examples of this include plaster, spray-on fireproofing, and textured ceilings such as popcorn ceiling. Asbestos provided these materials with enhanced durability, acoustics, and fire resistance. 

Plaster

Plaster is a common building material often used as the finished surface of walls and ceilings in a property. Plaster is also used for its protective and decorative nature. It often starts out as a powder and then is mixed with water to make a paste-like substance. The paste-like substance is typically applied to a substrate known as a lathe. The lathe can consist of either wood strips or metal (and even horsehair in very old buildings). The lathe is connected structurally to the wall studs or ceiling joists and the plaster is then applied. Plaster is often multi-layered with the most common appearance being a brown or beige inner coat, and a white soft coat on the exterior. Plaster can be used decoratively in properties and be molded into elaborate designs. It can also be used for acoustical purposes to dampen sound in areas and be used for fireproofing purposes. When sampling plaster, one should include all layers present from the exterior to the lathe. In my lab experiences, I have seen plaster range from 1 to 20% asbestos depending on the variety being analyzed. Acoustical, fireproofing, and decorative plasters tend to have a higher concentration than traditional plaster, but this isn’t always the case.

Textured Ceiling

Textured ceilings were used for decoration in many properties before 1980. Similar to plaster, textured ceilings are mixed with water and applied in various ways depending on the design. For popcorn ceilings, the mix is applied by spraying the mixture on a substrate such as a wall or ceiling. Popcorn ceilings are a friable material and with age and wear and can be rendered into a powder. It is possible to have a textured ceiling made out of stucco that is not considered to be surfacing materials by the Occupational, Safety, and Health Administration (OSHA). In a letter, they clarify that stucco does not normally contain asbestos and if asbestos is present, it may be in lower concentrations and tightly bound. Therefore, it would not be in the high-risk category of surfacing materials. 

Spray-on Insulation

Spray-on insulation was applied typically on structural areas of properties for fireproofing, soundproofing, and condensation protection. The fireproofing variety may contain amphibole asbestos such as amosite, tremolite, or crocidolite, but it may contain other varieties of asbestos as well. It is also known that vermiculite may also be found in spray-on fireproofing. Asbestos-containing spray-on insulation can typically have a high asbestos concentration, on par with thermal system insulation (TSI). 

Conclusions 

As stated in the previously referenced OSHA letter, surfacing materials are considered high-risk materials due to their friability. Also note, not all troweled-on materials are considered surfacing materials such as floor tile mastic, leveling compound, or paint. This is due to the material’s fibers being tightly bound. If you suspect asbestos-containing surfacing materials, contact Indoor Science to provide asbestos testing.   

Jordan Thomas

Jordan Thomas

Jordan Thomas is a Project Manager that performs indoor air quality assessments with a specialty in asbestos and lead. Mr. Thomas holds a Bachelors of Arts degree in Earth Science from DePauw University. Jordan is an ACAC Council-Certified Indoor Environmentalist (CIE), Licensed Lead and Asbestos Inspector, Licensed Air Sampling Professional, and HAZWOPER certified. He also holds an asbestos microscopist certificate from the McCrone Research Institute. Prior to working at Indoor Science, Jordan worked as an Industrial Hygienist at Environmental Analysis, Inc and as an Asbestos/Lead Analyst at Metro Technology Laboratory. In his words… “While not in the field, I’m a Nu-Jazz and movie enthusiast.”

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