Asbestos is a naturally occurring substance, so some
asbestos fibres are naturally liberated into the atmosphere. Everybody
is exposed to some asbestos fibres at all times, whether working under
an asbestos cement roof, playing in the local park or sailing across the
ocean. At the very low natural levels they do not cause a danger, they
become dangerous when the level of free fibres is increased by the inappropriate
use by man
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.
It does not mean that asbestos-containing materials
should be removed just because they contain asbestos, this would be counter
productive. The DETR give the guiding principles for the management of
asbestos materials as:
- Asbestos materials, which are sound, undamaged and
not releasing fibres should not be disturbed. Their condition should
be monitored on a regular basis.
- Where possible damaged materials should be repaired
and then protected as necessary, provided that the repair or sealing
will be durable and not likely to be disturbed.
- Removal should only be performed where repair is
not possible or the material is likely to be disturbed.
The Health and Safety Executive (HSE) published in 1999
guidance in the form of ‘Working with Asbestos Cement – HSG
189/2 @ £7.50. Other important reading is the Approved Code of Practice
‘Work with materials containing asbestos, Control of Asbestos Regulations
2006’ L 143 @ £13.50, A comprehensive guide to managing asbestos
in premises HSG 227 @ £12.50 and should be required reading for
anyone working on products, which may contain asbestos.
The handling of low-density insulation boards and spray
coatings containing asbestos is a skilled job that must be carried out
by a contractor licensed by the HSE to handle these products and is not
covered by this guidance note. The following advice is given for those
working with asbestos cement products.
Asbestos Cement is primarily a cement-based product
where about 10% to 15% w/w asbestos fibres are added to reinforce the
cement. Asbestos cement is weatherproof in that although it will absorb
moisture, the water does not pass through the product. It was 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. 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 and since they were
not weather resistant, if they had been fixed outside they would have
broken down long before now. If the product is moulded it will be asbestos
cement as low-density products were not moulded, except as half rounds
for pipe lagging.
When cementitious products like asbestos cement were
manufactured, they had a cement-rich surface. The asbestos fibres were
encapsulated within. Thus, occupants of buildings with asbestos cement
sheet or slate roofs are unlikely to be at any greater risk than people
outside in the fresh air. The small quantities of fibres released during
natural weathering are unlikely to be dangerous but significant and possibly
dangerous amounts of fibre can be released if the products are subject
to any abrasive cleaning or working. Thus, roofing operatives are more
at 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 his building and advises any contractors of their position,
so that they can take the necessary precautions.
General Guidance on the Working with Asbestos
The precautions required when working with an asbestos
cement product are relatively easy but must be followed or there is the
risk of creating dangerous quantities of fibres. If the precautions listed
below are followed it is unlikely that the Control level or action level
will be breached. There is not a requirement to use a “licensed
contractor” but the contractor should be competent.
- Carry out a risk assessment and write a method statement
to ensure that the risk is reduced to the minimum possible and certainly
that any fibre release is below the 10 Minute Limit and Control limit
and set out in the Control of Asbestos Regulations 2006. Information
on the 10 Minute Level and Control Limits can be found in the 'Approved
Code of Practice The Management of Asbestos in Non-Domestic Premises',
L127, ISBN 0 7176 6209.
- Ensure the operatives know that they are working
on asbestos containing products and that that they are adequately trained.
- Segregate the working areas with warning signs
- The operatives should preferably wear a disposable
mask that is CE marked to EN 149 with FFP3 particulate filters and disposable
overalls, which should be disposed of at the end of the shift as asbestos
- When working at heights follow the advice in HSG
33 Health and safety in roof work (1998). Old asbestos cement sheets
are very fragile.
- Keep the material wet when working on it.
- Avoid using power tools and breaking asbestos containing
products but carefully remove or crop fixings so that the product can
be removed in one piece. Carefully carry to the ground and either double
wrap in polythene or place in a covered skip.
- Where it is necessary to cut or drill asbestos cement
sheets, ensure the material is wet and if possible scribe and break,
if this is not possible use hand tools, preferably in the open air.
- Keep the site clean and tidy at all times and clean
up after work by dampening any dust and carefully placing in a polythene
bag for disposal as asbestos waste.
Where an asbestos cement roof or cladding is being repaired
it is lawful to reuse the existing asbestos cement sheets as long as the
correct working practices are used to keep asbestos exposure of the operatives
to the minimum possible. The AIC does not accept that this is good practice,
removing and replacing a sheet will put extra stress on to it and shorten
even further the second hand sheets life. We recommend that whenever an
asbestos cement product is removed it be replaced with a non-asbestos
Where an asbestos cement corrugated roof has come to
the end of its economic life, rather than replacing it, it may be safer
and more cost effective to leave the sheets in place and over-roof with
a non asbestos roofing sheet, adding insulation if required. This should
be discussed with you Competent Contractor or Designer.
Cleaning Asbestos Cement Roofs.
This should only be carried out if it can not be avoided,
moss and lichens although some may think them unsightly are not normally
detrimental. Asbestos cement is very fragile and so 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,
both can produce dangerous quantities of free asbestos fibres. Either:
- Use remote cleaning. This technique 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
- Cleaning with surface biocides. The biocides are
applied with low-pressure sprays or as washes. The roof is then left
for the moss and lichen to die, when it can 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 placed in plastic
bags and disposed of as asbestos waste.
Asbestos waste is any waste, which contains more than
0.1% w/w asbestos. It is subject to the waste management controls set
out in the Hazardous Waste (England and Wales) Regulations 2005 and the
agricultural waste regulations, with most properties if more than 200kg
of asbestos containing waste (500kg for agricultural asbestos waste) is
removed from site then the site has to be registered as a hazardous waste
producer with the Environment Agency. The waste must be consigned as soon
as possible by a licensed haulier to a dump licensed to take asbestos.
Your local authority should have a list of licensed haulier's and waste
dumps in you area.
The above is only a brief guide, it is not a complete
guide to Health and Safety responsibilities when dealing with asbestos
containing products, for more information contact your competent contractor,
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.
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