There are millions of square metres of asbestos fibre cement roofing all over the country, covering commercial buildings, domestic homes, garages, outbuildings and agricultural barns. It was used until relatively recently (1999), because it was cheap, quick to lay and has a very long useful life.
In fact there is usually very little asbestos in this type of sheeting Typically only 10%-15% of the material comprises asbestos which is tightly bound into the cement and the material will only give off fibres if it is badly damaged or broken. The vast majority of these roof coverings use white (Chrysotile) asbestos fibres. This type of white asbestos is common in many older roofed areas, and is classed as a low risk material by the Health & Safety Executive.
The more dangerous ‘blue asbestos’ (crocidolite) or ‘brown asbestos’(amosite) are mostly found inside very old buildings used for lagging, insulation and paneling etc. In general roofing and guttering were manufactured using white asbestos as a binder. If there is any doubt a sample can be taken and a laboratory test arranged to pinpoint the exact type, however this is rarely necessary.
The Health & Safety Executive has stated in they would rather that asbestos roofs be left in place and not disturbed, if they do begin to leak it is preferred they are over-roofed or sealed. Not as foolish an idea as it first sounds. Doing this does mean the sheeting will not be disturbed, which is the only time there is any potential danger.
Also, it surprises most people to discover that the same identical looking material is still available today, and widely used. Although is now called Fibre Cement roof sheeting, other binders nowadays being used to replace the asbestos.
B & S Roofing – Simple Solutions…
B & S Roofing have many years experience with this material. The expensive option is to re-roof with similar or completely new roof coverings. Alternatively we have a unique economic and aesthetically pleasing over-roofing system available. This is a GRP (glass reinforced polyester) over-roofing system The new coverings are overlaid to the entire roof area. The new coverings match the profile of the existing sheeting, being secured through the roof sheets directly into the purlins.
The GRP sheets are specifically manufactured to each project, and are laid, where possible, in a single continuous run from ridge to eaves, thus eliminating any end-laps, this where the sheets overlap, the most common place for leaks to occur in old asbestos roofs, due to the sheets distorting.
Other options, mainly on commercial buildings are to over-roof using modern box profiled steel sheeting which usually incorporates an insulation layer.
