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Asbestos insulating board

Asbestos insulating board (AIB)

Asbestos insulating board is a low-density board that has been used for a wide variety of construction purposes. It should not be confused with asbestos cement boards, which are more compressed and have a lower asbestos content.

The widespread use of AIB means that it can be found in all types of properties built or refurbished after World War 2. The material has been used as a fire-retardant board for compartmentalisation, as well as a general building board for dry-lining purposes, forming ceiling bulkheads and soffits, service ducts, etc.

Although not as friable as sprayed coating or insulation, this material is very friable and should only be worked on by a licensed asbestos contractor. The period of use was extensive, from the 1950s through to the 1980s, and the boards have the appearance of modern products such as Supalux, Masterboard and Glasroc board. It can be difficult for untrained personnel to distinguish between AIB and modern alternatives, especially once painted or decorated. This means surveyors should be aware that not all the asbestos on site may have been identified.

In addition to the commercial use of the material, the products were also sold for domestic use, meaning AIB can be encountered in unexpected places.

  • Risks to surveyors
  • Risk to clients

Risks to surveyors

Building surveyors and those inspecting premises will encounter AIB in a wide variety of forms. Surveyors inspecting commercial properties may disturb ceiling tiles, service riser covers, or fire door linings as they undertake property inspections. Those surveying domestic properties may encounter the material where it has been used as the backing to loft hatches.

If maintained in good condition, AIB should not present a health risk but often the condition of these materials is poor. Surveyors acting as agents in properties where use of AIB is extensive should be aware of the additional costs that will arise for the operation of the building. In addition, where the material has been used to line service risers, consideration should be given to the age of the services within the riser, as the presence of the material will prevent ready access to them.

Risk to clients

Many system-built structures made extensive use of AIB. An example of this is the CLASP building system used in the education sector, and to a lesser extent mining and railway sectors. This is a system with a steel framed structure where AIB has been used to clad the structural steels, provide infill panels around windows, and offer fire protection to service risers. During the construction of these types of properties, insulation board offcuts often found other uses such as packing around doorframes and lintels.

The higher incidence of asbestos use in some system-type properties means that clients will encounter increased difficulties and cost in the day-to-day management of the property.

In commercial buildings the use of AIB can be extensive. Here are a few examples:

  • backing to raised/computer floors where the board is applied for fire protection
  • cladding and core for fire doors to enhance fire protection
  • general boards for service risers and infill panels
  • formation of ducting
  • ceiling tiles and
  • plant and machinery.

In domestic premises, AIB has been used both internally and externally: internally for ceiling lining, lining to boilers and airing cupboards, and fire protection for garage ceilings; and externally to form soffits.

Case studies

  • AIB was used for heat containment in manufacturing premises. Here the board had been cut and used for making counter tops, heat shields and the boxing for ovens. In this case, the material was identified during due diligence of the business and had an adverse effect on the sale.

    Asbestos insulating board used for heat containment in industrial processes (© Thames Laboratories)
  • AIB ceiling tiles were present in an office building. Examination of the site identified that in some locations the material was being regularly disturbed to provide access to the ceiling voids. The risks of this had not been adequately considered and were not documented. Disturbance of these types of materials is generally unplanned and is associated with a wide range of activities, from electrical and plumbing work, to installing alarms and data cabling.

    Asbestos insulating board ceiling tiles (© Thames Laboratories)
  • This relates to a system-built residential property where the external cladding was asbestos cement. To provide fire protection for the property, the kitchen walls were lined with AIB and the cavity between the first and ground floor was also lined with AIB. To remove the AIB from this property, the building would need to be dismantled.

    Prefabricated residential property with extensive use of asbestos both internally and externally (© Thames Laboratories)
  • Here, AIB was used as compartmentalisation within the loft space of a property. The material is unsealed and is likely to have been cut in situ so dust from it may be present throughout the loft. This presents a potential risk to surveyors as they inspect properties or items that are stored in such locations.

    Asbestos insulating board firebreaks in roof space (© Thames Laboratories)
  • In this example, AIB was found forming cases for displays to provide fire protection. It was also found as a lining for picture frames, where it was used to protect pictures from smoke damage or as a mounting board.

    Fine art framed in the UK in the 1950s and 1960s was occasionally backed with asbestos insulation board. Some of the artworks encountered bear the label of Jeremy Simmons, Specialist Frame Maker, Great Hormead Dane, Near Buntingford, Hertfordshire. It is not known if this framer attached the artworks to the board or simply framed artworks that were already attached. Some of the artworks attached to AIB at that time were later reframed and so AIB may be encountered in more modern frames and framer’s labels may have been lost or covered.

    During 2016 a group of 38 artworks with a seven-figure insurance valuation were carefully separated from asbestos insulation board backings at Museum Conservation Services Ltd. in Cambridge. The artworks were all cleaned on the recto, verso and edges and any areas where asbestos fibres could have been hidden, such as between imperfectly adhered layers of paper/board were also dealt with. 

    The artworks had been mounted in the 1950s or 1960s. Not all bore framer’s labels but those that did were labelled ‘Jeremy Simmons, Specialist Frame Maker, Great Hormead Dane, Near Buntingford, Hertfordshire’. It is not known if this business attached the artworks to the board or simply framed artworks that were already attached, though one artwork bore a framer’s inscription giving measurements accompanied by the word ‘asbestos’. Some of the artworks had certainly been reframed at a later date. A variety of British and foreign artists were represented in the group and so this is not restricted to a particular artist or school. Artworks that appear to be mounted in a similar manner can be seen in fine art auction catalogues though from the illustrations it is impossible to be certain.

    Asbestos insulating board used as backing to picture frames (© Museum Conservation Services)