Asbestos An unholy problem? by ALAN PECK of Tersus Consultancy
H
ailed as the wonder building material when first used in the 1890’s and reaching its peak use in buildings around the mid 1970’s it’s not unreasonable to find asbestos used extensively in schools and churches. Asbestos containing materials take on many forms and have many uses in construction from simple floor tiles to board materials, anti-condensation products and, of course, thermal insulation. So good was asbestos that asbestos containing materials could be mixed with other materials to produce rigid products which could be moulded, formed, compressed, machined or just used in its raw fibrous state as pipe and boiler insulation or sprayed onto surfaces as an asbestos coating. Tradesmen became so adept at working with asbestos they produced mini works of art – one can only admire the perfect roundness of hand applied pipe insulation in many, still operating boiler houses or the alabaster type finish they managed to apply as sprayed coatings to the soffits of commercial offices, department stores, hotels, hospitals, schools and churches. The thing is, of course, it is very difficult to know what is asbestos and what is not which is why the largest group at risk from asbestos is currently tradesmen and why around 5,000 people per year die from asbestos related diseases. Asbestos was finally prohibited in the UK in 1999.
Case Study Who would have thought the ‘decorative’ finish to the underside of a church roof in Yorkshire was asbestos? Over the years, water penetration had caused the surface of the asbestos coating to deteriorate and even start to delaminate in certain areas causing the risk of asbestos fibres being released to increase dramatically. The only option was to remove the problem area and to fully encapsulate the remainder. The asbestos was found to be clearly marked on the original architect’s drawings for the church but for some reason did not appear on the asbestos register. It was clear that a definitive asbestos survey was required in order to fully locate the presence, condition and location of any asbestos containing materials. Access to the high level areas was extremely difficult as elevating equipment had to be sourced that would fit through a standard door and be capable of reaching the height required. Following a thorough site inspection it was possible to formulate an asbestos management plan and confirm that all areas, with the exception of the two areas of low level
Tersus surveyor taking samples of sprayed asbestos roof, were sound, well encapsulated and posed a manageable risk. The recommendation therefore was the removal of the whole of the sections of roof containing the damaged areas and to commence an air monitoring regime within the church to check the airborne fibre concentration of the remainder of the building. This was to prove that the building would continue to be safe for occupation by unprotected people after the removal works. Asbestos removal works presented their own problems. Firstly the removal contractor had to be carefully selected to ensure they had the experience to deal with this type of asbestos material and could approach the works in a sympathetic manner given the nature of the building. The other problem was that the church was regularly used, allowing only seven days to complete the work between weddings. The removal of this type of asbestos, commonly known as limpet, is notoriously difficult as the individual asbestos fibres adhere to any rough surface. The material is also extremely friable and capable of releasing fibres many thousands of times above the control limit. Under these circumstances fibre suppression is all important, not only for the safety of the operatives but to reduce the amount of free fibre when the area is finally cleaned and decontaminated. To cope with the very rough surface, the underside of roof was hand painted with an asbestos encapsulation product to lock down any residual fibres prior to being plaster rendered and redecorated by other tradesmen to match the treated areas. q
Above (left) – damage to sprayed asbestos coating visible either side of the lower roof valley; and (right) – inside the asbestos enclosure, an asbestos operative carefully removes the asbestos under controlled conditions
• The Control of Asbestos Regulations 2012 requires all dutyholders to formulate an asbestos management plan for the property for which they are responsible. The starting point for this plan is an Asbestos Survey Report in accordance with HSG 264, preferably by a UKAS accredited consultancy to ISO/IEC 17020.
19