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Asbestos insulation

Asbestos insulation

Asbestos has been used as a thermal insulation material since the late 1800s, in the form of hand-applied lagging, asbestos-filled blankets, pre-formed asbestos sections and sectional materials that have a similar appearance to modern ridged section insulation.

Because the material has been used for thermal insulation it is generally easier to identify in properties than some other types of asbestos products.  The use of asbestos for these types of applications mostly ceased in the mid-1970s. Therefore, when considering these types of materials, the services to which they have been applied are going to be over 40 years old, so dealing with the asbestos in isolation could result in other issues. Removal of the material may cause damage to services, so consider removing the pipework with the asbestos still attached. This will still necessitate the use of a licensed asbestos contractor but should avoid legacy issues.

Over time a lot of this asbestos has been removed, sometimes in conjunction with the replacement of aged plant and pipework, which provides the most favourable conditions for achieving the complete removal of asbestos. However, bear in mind when dealing with older properties that even in these cases the standard of workmanship can vary considerably.

Common locations for this material are: plant rooms, where it was applied to boilers, vessels and pipework; service risers; and loft spaces, where it was applied to pipework. The material can take several forms, such as slabs applied to boilers or cylinders, hand-applied materials installed on boilers and pipework, and sectional insulation applied to pipework.

  • Risk to surveyors
  • Risk to clients

Risk to surveyors

Asbestos insulation can often be found in confined spaces such as plant rooms, roof spaces, services risers, and tunnels. Disturbing these materials can produce substantial levels of airborne asbestos fibre. In a confined space, the levels of fibre will not reduce quickly, and this can result in greater risk due to protracted exposure. Past shoddy asbestos removal often left residue on walls and ceilings, so surveyors should look out for this during inspections. Although generally confined to commercial properties, this type of insulation can also be found in domestic properties, particularly larger dwellings constructed prior to the 1970s.


Risk to clients

Although these materials present a significant risk to health, they are generally only found in locations where staff access is limited. The risk to clients can be mitigated by having appropriate management strategies in place for services.

Case studies

  • An asbestos survey has identified asbestos insulated pipework within several risers in a building. The survey report has been reviewed by several building professionals and contractors prior to work starting on site, and the information had been incorporated into a pre-site health and safety file. Upon commencement of works on site, the contractor breaks open a wall and discovers an unreported riser containing asbestos insulation.

    The issue with this site is that the report did not consider the full extent of the services; asbestos risers were identified on the ground, first and third floors but not on the second or fourth floors. An understanding of the building heating flow and return system would have identified that the survey was insufficient and due consideration had not been given to the possibility of risers on other floors. Further investigation in conjunction with a service engineer identified asbestos-containing risers were present on all floors, and within both the roof space and basement, forming a flow and return system.

    The impact of this was significant as the client’s original objective with this building, which was going to be used for educational purposes, was to remove all of the asbestos. The failure to identify the additional asbestos had not been budgeted for, and the cost of removal increased threefold, meaning all of the material present in the floor voids had to be left in situ to reduce costs.

    Damaged asbestos insulation on stairwell (© Thames Laboratories)
  • This involved a listed property where the client planned to replace heating services over a five-year period. The specification was drawn up for the removal of asbestos insulation applied to pipework in floor voids. Phase 1 of the work was undertaken, with the asbestos removed and the pipes left in situ. Following this work, the client experienced an increase in leaks to the pipework in the areas where the asbestos had been removed. Examination also revealed that where pipework was close to the ground, not all of the asbestos had been removed, as contractors had been unable to clean the rear of the pipes, and moving the pipes was inducing leaks. All the contractors and consultants involved in the phase 1 work were removed from the project, and the solution identified was the systematic removal of asbestos and pipework to ensure all of the asbestos was removed, and the installation of new pipework in a phased programme of work.

    Asbestos insulated pipework in floor void (© Thames Laboratories)
  • A programme of heating replacement had been undertaken at a university, and buildings moved from a central boiler room supply to standalone heating systems. The focus of this work was the local disconnection of the old heating supplies and the installation of the new boilers. In doing this, properties were disconnected from the district supply, the central boiler rooms were refitted as a recreational space and the assumption was made that the asbestos on site had been dealt with. No consideration was given to the distribution system as part of the plan, and asbestos insulated pipes remained throughout the site, some in close proximity to areas of high pedestrian traffic, with no appropriate management processes put in place.

    External asbestos insulated pipework with hard set exterior (© Tim Elliott)
  • A building surveyor undertakes a valuation of a large domestic property. The surveyor notes the presence of an old boiler, but does not note the presence of insulated pipework. The client subsequently purchases the property, begins refurbishment work and discovers asbestos insulated pipework in the floor voids and loft of the property, which subsequently results in a claim against the surveyor.

    Sectional asbestos insulation in floor of residential property (© Tim Elliott)
    Sectional asbestos insulation in roof space of residential property (© Tim Elliott)