Asbestos has been added to a huge variety of products and whilst certain factors will help indicate if the product contains asbestos the only way to be sure is for the material to be sampled.
Key dates for Identifying Asbestos
A key factor will be the age of the premises – by understanding when asbestos ceased to be present within certain materials you are likely to have a reasonable idea as to whether the material contains asbestos e.g.
- Textured coatings were often manufactured with asbestos up to 1984.
- The asbestos prohibition regs 1985 banned the import, supply and use of Amosite and Crocidolite. So the use of Asbestos Insulation Board (containing these types of asbestos) should in theory have stopped after this date. A voluntary ban on the importation of Amosite was introduced in 1980.
- The use of asbestos within sprayed insulation was stopped in 1974 – use of Crocidolite ceased in 1972.
It MUST be noted that these dates are a guidance only and stocks of products are known to have been used long after these cut off dates or machinery used to produce AIB was then used to produce ‘Supalux’ and it is not uncommon for the ‘Supalux’ to be contaminated with asbestos!
Properties of Asbestos
A second factor in understanding if a product contains asbestos is understanding the properties of asbestos. Asbestos fibre is mechanically strong and highly resistant to heat and chemical attack. Because of its fibrous nature asbestos fibre can be woven into fabrics and used as reinforcement for cement and plastics. With this simple knowledge and the age of the property a surveyor is able to predict where asbestos materials may have been used and even the type of asbestos that is likely to have been used. Some obvious examples would be;
Asbestos Cement
- Asbestos cement – Cement by its nature is a relatively hard and resistant material but the asbestos ( between 10-15%) is added to further strengthen and reinforce it. The material is therefore associated in areas of buildings where characteristics such as strength and rigidity are required in addition to its heat resistant properties. Examples would be external panelling or roofing sheets or where it is used as a shuttering to set concrete. Whilst all 3 of the main asbestos type have been used Chrysotile is most associated with this material because of its high tensile strength (long, wavy fibres) and the fact that more Chrysotile was imported into the country than all of the other asbestos types. A good indication of asbestos cement is a pimpled pattern on the surface of a profiled sheet. Asbestos cement was replaced by a modern fibre cement, containing synthetic fibres in the 1980’s. Unfortunately this product was produced to closely resemble the original asbestos cement and sampling may be required to determine if the material contains asbestos.
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Close up of asbestos cement roof panel
A close examination of the edges of the cement panel will often reveal clumps of white fibres (Chrysotile – white asbestos) – this is particularly evident if you use a small magnifying glass.
Asbestos Gaskets
- Gaskets have a widespread use with the construction industry. Gaskets are required as a friction product, needed to be tough and flexible and are needed to resist high temperatures. The ideal material for this product is asbestos and the ideal asbestos type is Chrysotile, which can be used to form compressed gasket material for use between pipe flanges or as a string or rope which can be used as a seal around skylights or windows to provide an airtight joint.
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Compressed asbestos flange gasket to pipework
