Over-roofing is presented as an environmentally friendly and cost-effective alternative to the removal and disposal of asbestos roofing. It involves installing a new roof over the existing asbestos roof, leaving the asbestos in place. This avoids the health risks of asbestos removal and the high costs associated with removal and hazardous waste disposal. Some benefits of over-roofing include minimizing disruption to building occupants, eliminating costly asbestos removal and disposal, reducing project timelines, improving worker safety, increasing energy efficiency when insulation is added, and preventing further environmental degradation from asbestos in landfills. The existing asbestos roof provides a work platform, while a specialized vacuum captures any dust or fibers created during the installation process.

1. ASHGRID
Over-Roofing Asbestos Roofs
The Environmentally Friendly & Energy Efficient
Alternative to Removal and Disposal
www.ashandlacy.co.za
Manufactured by
Ash & Lacy Buildings Systems Ltd UK
Distributed by
Ash & Lacy South Africa (Pty) Ltd

2. ASHGRID
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Asbestos in the South African Roofing Industry
Asbestos is a naturally occurring fibrous material that, due
to its non-corrosive and thermal properties has been used
to manufacture a vast range of asbestos-cement roofing
products in South Africa. Asbestos fibres are known to pose
life threatening health risks when inhaled such as asbestosis
and mesothelioma. Use of asbestos containing products is now
banned in South Africa however the legacy will remain with us
for many years to come as asbestos-cement roofing products
were the preferred choice of roof covering for many years.
Asbestos Cement is primarily a cement-based product where
about 10% to 15% 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, soffits, rainwater gutters,
down pipes and fascias.
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 however significant and possibly
dangerous amounts of fibre can be released if the products are
subject to any abrasive cleaning, damage or removal.
Where an asbestos cement corrugated roof has come to the
end of its economic life, it is safer and more cost effective to
leave the sheets in place and over-roof with a non-asbestos
roofing sheet whilst adding insulation if required.
Over-Roofing
Over-roofing is an environmentally sound way to deal with roof
coverings that contain asbestos. The Asbestos Information
Centre of the United Kingdom http://www.aic.org.uk states:
“Asbestos materials, which are sound, undamaged and not releasing
fibres, should not be disturbed. Their condition should be monitored
on a regular basis. Removal should only be performed where repair is
not possible or the material is likely to be disturbed.”
Enclosure of asbestos-cement roofs by means of over-roofing is widely
recognised internationally as a safe, cost effective & non-invasive
alternative to removal.
What are the benefits of Over-Roofing?
• Minimises building occupants risk and disruption of trade
South African legislation stipulates that occupants of a building where
asbestos roof sheets are being removed vacate the premises. Leaving
the existing roof covering in-situ allows the occupant of the building
to continue with their ‘day to day’ business operations without costly
disruptions to trade. Consequential damage due to inclement weather
& falling debris usually associated with conventional re-roofing are
eliminated when over-roofing.
• Eliminates rising costs associated with removal & disposal
of asbestos
South African legislation stipulates that the removal & disposal of
asbestos may only be carried out by registered asbestos removal
contractors. Removal & disposal costs are high due to safety
procedures, transportation & disposal costs.
Over-Roofing Asbestos Roofs
Installation of the Ashgrid
Over-Roofing System
Existing asbestos-cement roof sheets are left
in position eliminating the labour intensive
and dangerous task of removal.
The innovative Ashgrid system is installed in the troughs
of the existing asbestos-cement roof sheets with the
brackets fixed through the roof sheets directly into the
existing steel or timber purlins. The Ashgrid brackets are
available from 60mm to 280mm to create a cavity for the
installation of insulation to achieve the required r-value.
All drilling is carried out in conjunction with a specialised
H-Series vacuum which is designed to capture any dust
and asbestos fibres created during the drilling process.
This powerful vacuum cleaner is fitted with a Ulpa Filter for
99.999% efficiency at 0.12 micron. It is ESD safe, meets
HSG264 standards of surveying and is fully compliant with
BS EN 60335-2-69.
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3. ASHGRID
3M +27 832151782 (International)www.ashandlacy.co.za
• Labour & time savings
Leaving the existing roof covering in place
eliminates the removal phase. This in turn
reduces the duration of the project which
contributes to significant financial savings.
• Improved Health & Safety
The existing asbestos-cement roof sheets
remain in place providing the contractor
with a platform to work off. This significantly
simplifies the fall protection plan required.
The majority of loose asbestos fibres are
present between the sidelaps of the existing
asbestos-cement roof sheets. These fibres
are only at risk of being released when the
roof sheets are lifted and removed. Leaving
the existing asbestos-cement roof sheets in
position eliminates the risk of releasing fibres
and exposing the contractor or occupants to
contamination.
• Energy Efficiency
Over-roofing with the Ashgrid Spacer
System creates an engineered, structurally
defined cavity between the old and new
roof coverings. When insulated this cavity
dramatically improves the overall energy
efficiency of the entire building. With ever
increasing electricity prices in South Africa,
energy consumption has become a big
concern for most property owners and
tenants. Significant financial savings are
possible over the life cycle of the new roof
covering when insulated appropriately.
• Acoustic performance
Creation of an insulated cavity dramatically
improves the acoustic performance of a roof.
Acoustic performance is imperative when a
condusive environment is required in places
of learning, libraries, broadcasting facilities,
court houses etc.
• Environmental benefits
Our landfill sites are filling up at a rapid rate.
Over-roofing asbestos-cement roofs prevents
further deterioration of the product rendering
it inert & safe. Whereas asbestos-cement
products that are disposed of in landfill sites
continue to degrade due to exposure to
the elements. This continued uncontrolled
deterioration has a severe impact on our
already fragile environment.
• Security
Over-roofing incorporates a second layer
of roof covering which provides additional
security. The majority of commercial break-
ins occur through the roof. This additional
layer of roof covering provides an extra barrier
to deter criminals.
The new outer roof covering is
installed directly to the bars of the
Ashgrid system. The Ashgrid system
is compatible with all forms of
pierced and concealed fix profiled
steel sheets and is engineered to
evenly distribute the loads into the
existing roof structure.
Insulation is installed to the newly created cavity based
on the required thermal, acoustic and fire performance
requirements of the specific project. Installation of
insulation is not a prerequisite.
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4. Ashgrid SA reserve the right to amend product specifications without prior notice. The information, technical details and fixings
advice are given in good faith but are intended as a guide only. For further information please contact Ashgrid SA. All products are
supplied in accordance with the Ashgrid SA & Conditions of Sale.
www.ashandlacy.co.za
Manufactured by Ash & Lacy Buildings Systems Ltd UK
Distributed by Ash & Lacy South Africa (Pty) Ltd
M +27 832151782 (International)
F 086-5376079
E dion.marsh@ashandlacy.com
August 2014