What is Asbestos Cement?
Asbestos cement is primarily a cement-based product where about 10-15% w/w of asbestos fibres are added to reinforce the cement.
As well as an insulation and fireproofing aid, asbestos cement was used due to the fact that it is weatherproof in that, although it will absorb moisture, the water does not pass through the product.
What was Asbestos Cement used for?
Corrugated sheets, slates, moulded fittings, soffits and undercloak, water cisterns, rainwater gutters, down pipes, pressure pipes, underground drainage and sewer pipes, sills, copings, chalkboards, fascias, infill panels, etc.
Identifying Asbestos Cement
It is sometimes difficult to tell the difference between an asbestos cement product and a low-density insulation board. Where the product has been used as a roofing or cladding product (open to the weather), you can be confident that the product is asbestos cement.
Manufacture of all low density products was stopped in the late 70’s; as they were not weather resistant, if they had been fixed outside they would have broken down long before now. If the material is moulded then it will be asbestos cement, as low-density products were not moulded, except as half rounds for pipe lagging.
Is asbestos cement safe? Who is at risk?
The asbestos fibres in asbestos cement are found within the cement itself; the asbestos cement will have a cement-rich surface, and thus the fibres are contained.
The small quantities of fibres released during natural weathering of asbestos cement are unlikely to be dangerous.
However, significant – and possibly dangerous – amounts of fibres can be released if the cement is subject to any abrasive cleaning or working.
Thus, roofing operatives and those in other similar professions face increased risk from fibre exposure than any residents inside a building. It is important therefore that building owners keep a note of any asbestos containing products in their building and advises any contractors of their position, so that they can take the necessary precautions.
- Residents of a building constructed from asbestos cement are quite safe.
- Roofing operatives and other professions involved in working directly with asbestos cement should take the necessary precautions.
Working with asbestos cement in your job or project? Ensure you and your workforce are adequately trained for working with asbestos – invest in an online Asbestos Awareness training course.
Cleaning Asbestos Cement Roofs
This advice should only be actioned if cleaning of an asbestos cement covered roof or area can not be avoided.
As asbestos cement is highly fragile, the recommendations in HSG 33 Health and safety in roof work (1998) must be followed:
- Do not clean by dry scraping or by pressure washing, as both can release dangerous quantities of asbestos fibres. Instead, use:
- Remote cleaning: a technique that involves skilled operatives using units with enclosed rotary cleaning heads and high-pressure water jets. the filtering of the water run off and the disposal of the filter waste as asbestos waste. It should only be carried out by skilled specialist contractors.
- Cleaning with surface biocides: after applying biocides with low-pressure sprays or as washes, the roof is left for the moss and lichen to die, when it can then be gently brushed from the roof with soft brushes. It is important that the roof is kept wet during the brushing and the waste is carefully collected and placed in plastic bags to be disposed of as asbestos waste.
Please note that although many regard them as unsightly, moss and lichens are not usually detrimental to a roof surface.
The Asbestos (Prohibitions) (Amendment) Regulations S.I. 1999 No. 2373/99 imposed a total ban from November 24th, 1999 on the selling and fixing of asbestos containing products. This ban extends to selling and fixing second-hand asbestos cement products. It does not affect the sale of property that contains any asbestos cement product.
Disclaimer: All of the above information should be used only as a brief guide – not a complete guide – to Health and Safety responsibilities when working with asbestos containing products; for more information contact a competent contractor or designer.
The above guidance is given with the best intentions but nothing in this advice shall create or be deemed to create any obligations, whether expressed or implied, on the AIC.