Plaster materials & their relationship with asbestos

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Plaster material used for coating walls, ceilings and partitions is the most common building material received by Chemsafety’s Laboratory for asbestos identification.  After observing the last 100 samples received by our laboratory, we found that 58% were classified as plaster or textured plaster by us.  That is why we decided to dedicate this article to this material, so you can get to know it a little bit better.

Plaster materials are mostly made of gypsum, lime, or cement, and are used for a protective or decorative coating of walls, ceilings, moulding, and casting decorative elements.  When we describe the sample as “Plaster” in our analysis report, this usually means that the material was used in the building interior, but it can also be for external applications.  Another term used for this material is stucco or skim coat which is often produced with a surface decoration, rather than just being flat.  We refer to these samples as “Textured”.

Up until the middle of the 1980s asbestos was commonly added to plaster mixtures to make it more resistant to fire, increase the material flexibility and insulate buildings.  According to HSE Document HSG 264 (2012), textured coatings, paints and plasters used for decorative effects can contain up to a few per cent (3-5%) of white (chrysotile) asbestos.  The asbestos within plaster and textured materials are well contained, but may be released when the material starts to degrade or is disturbed by sanding or scraping.  This makes it very important to test for the presence of asbestos before you do any renovation or demolition of walls or ceilings in buildings built or refurbished before 2000.

It is very common to receive non-homogeneous plaster materials in our laboratory, meaning that the presence of asbestos is not evenly distributed in the material, e.g. some “pieces” have asbestos and other “pieces” don’t. The reason for this could be:

  • Different batches of plasters were used on the same wall.
  • The wall was refurbished/patched with different plaster (with or without asbestos)
  • The sample is a composite of different locations (e.g. the sample contains plaster material from different walls within the same room).
  • Different layers of plaster are present, this is why when collecting samples it is important to make sure that all the layers are accounted for in the sample.

Because of these peculiarities and for your own safety it is always recommended to hire an asbestos surveyor or sample collection professional, like Chemsafety, to do this job.  If the asbestos is present in a homogenous way or not, plaster on the wall, or walls of a room, should be treated as containing asbestos, and depending of the situation you will need to contact an asbestos removalist to remove the material.

Example of a textured material over plaster board without magnification (left) and under the stereo microscope - 40x magnification (right).