Asbestos Plaster Layers
Example of an older, asbestos plaster wall system on wood lath. While these plaster materials may look like any typical plaster, that's partly the point of this photo: asbestos-containing plaster might be present in any ordinary-looking plaster material; whether the plaster is troweled-on or spray-applied onto wood or metal lath, on gypsum wallboard panels, onto concrete or applied to any type of substrate. In this particular example, asbestos was found within the thicker, plaster base layer.
For a more conclusive determination about whether or not plaster contains asbestos (or any type of suspect material for that matter), multiple bulk samples of the material, including all layers of a "system", are to be properly collected by a trained, certified, and accredited ("licensed") asbestos inspector, and then tested via specialized, laboratory microscopy method(s) to determine asbestos presence or absence and its respective percentage therein. The testing can be relatively inexpensive, ranging on average between $6-to-$30 USD (or more) per sample, per layer, often depending upon required turn-around time
Another point of interest regarding the plaster system in the above example is that there are actually three layers of plaster: the bottom ("render") thick base-layer; the thin ("floating" or "setting") skim-layer, and a textured finishing layer. Each type of plaster layer, (base-coat, skim-coat, textured surfacing, etc.) has been known to contain asbestos.
The coarse, base plaster in this instance, sometimes referred to as "brown-coat" or "scratch-coat", in addition to asbestos, also contains small aggregate and animal hair fibers (likely bovine, equine, porcine, caprine, or cervine). These constituents are more visible in the inset image.
Although not in this particular case, sometimes the white, finish layer or "skim-coat" may contain asbestos. Or, even the textured finish, stucco-style spackling may contain asbestos as well.
Particular attention to different types of plasters, possibly applied in different areas, such as: mechanical rooms, boiler rooms, fan rooms, auditoriums, stages, arenas, churches/temples (or other places of worship), cafeterias, theaters, air plenums, utility areas, electrical rooms/vaults, workshops, stairwells, corridors, decorative applications, lobbies, elevator shafts, radiator shielding, instrumental-band/choir rooms, library/media centers, etc.; are all unique functional spaces that should be especially considered when evaluating the potential for differing types of plaster applications.
Further yet, ceiling plaster may contain asbestos and wall plaster may not, despite being in the same functional space and having similar appearance/texture.
Of further importance in distinguishing different types of plasters that may exist in a building is knowing the renovation history of the structure, and also if additions were constructed or patching was installed that contain plaster(s) applied at later date(s). Each plaster from differing dates of construction or patches should be assessed separately.
There are also examples of asbestos inspection surveys in multi-floor buildings where asbestos (> 1% content) was found in wall/ceiling plasters on certain floors, but not others (trace to < 1%).
Keep in mind that if asbestos (>1%) is identified in one layer of a plaster application, then the entire plaster "system" is treated as an ACM.
Additionally, don't forget about potential lead or cadmium-based paint or respirable silica dust exposure issues when dealing with older painted plaster materials during demolition or renovation activities.
Asbestos Plaster Layers
Example of an older, asbestos plaster wall system on wood lath. While these plaster materials may look like any typical plaster, that's partly the point of this photo: asbestos-containing plaster might be present in any ordinary-looking plaster material; whether the plaster is troweled-on or spray-applied onto wood or metal lath, on gypsum wallboard panels, onto concrete or applied to any type of substrate. In this particular example, asbestos was found within the thicker, plaster base layer.
For a more conclusive determination about whether or not plaster contains asbestos (or any type of suspect material for that matter), multiple bulk samples of the material, including all layers of a "system", are to be properly collected by a trained, certified, and accredited ("licensed") asbestos inspector, and then tested via specialized, laboratory microscopy method(s) to determine asbestos presence or absence and its respective percentage therein. The testing can be relatively inexpensive, ranging on average between $6-to-$30 USD (or more) per sample, per layer, often depending upon required turn-around time
Another point of interest regarding the plaster system in the above example is that there are actually three layers of plaster: the bottom ("render") thick base-layer; the thin ("floating" or "setting") skim-layer, and a textured finishing layer. Each type of plaster layer, (base-coat, skim-coat, textured surfacing, etc.) has been known to contain asbestos.
The coarse, base plaster in this instance, sometimes referred to as "brown-coat" or "scratch-coat", in addition to asbestos, also contains small aggregate and animal hair fibers (likely bovine, equine, porcine, caprine, or cervine). These constituents are more visible in the inset image.
Although not in this particular case, sometimes the white, finish layer or "skim-coat" may contain asbestos. Or, even the textured finish, stucco-style spackling may contain asbestos as well.
Particular attention to different types of plasters, possibly applied in different areas, such as: mechanical rooms, boiler rooms, fan rooms, auditoriums, stages, arenas, churches/temples (or other places of worship), cafeterias, theaters, air plenums, utility areas, electrical rooms/vaults, workshops, stairwells, corridors, decorative applications, lobbies, elevator shafts, radiator shielding, instrumental-band/choir rooms, library/media centers, etc.; are all unique functional spaces that should be especially considered when evaluating the potential for differing types of plaster applications.
Further yet, ceiling plaster may contain asbestos and wall plaster may not, despite being in the same functional space and having similar appearance/texture.
Of further importance in distinguishing different types of plasters that may exist in a building is knowing the renovation history of the structure, and also if additions were constructed or patching was installed that contain plaster(s) applied at later date(s). Each plaster from differing dates of construction or patches should be assessed separately.
There are also examples of asbestos inspection surveys in multi-floor buildings where asbestos (> 1% content) was found in wall/ceiling plasters on certain floors, but not others (trace to < 1%).
Keep in mind that if asbestos (>1%) is identified in one layer of a plaster application, then the entire plaster "system" is treated as an ACM.
Additionally, don't forget about potential lead or cadmium-based paint or respirable silica dust exposure issues when dealing with older painted plaster materials during demolition or renovation activities.