Home Home Improvements An asbestos cement roof

An asbestos cement roof


Only recently I was phoned by a frail elderly lady who was concerned that a rogue builder was proposing to charge her hundreds of pounds to remove and replace her garage roof. I popped round to see her and found that the work was not really required as a matter of urgency and in her circumstances, should not have been prohibitively expensive.

The roof was shallow pitched with a central asbestos capped ridge and all weathered in corrugated asbestos cement panels, probably some 30 or more years of age. Asbestos was banned from use in buildings in 1999 but is still seen in many dwellings, often in rainwater goods, soffits and water tanks. Asbestos cement building materials typically contain between 10-15% of white asbestos (there are three main types), bound in a cement base. It is the fibres from the asbestos that can be a danger to health if they are inhaled so asbestos Containing Materials (ACMs) should never be abraded to create dust.

In this instance the roof was leaking where metal fixings secured the panels to the roof frame, and also where the asbestos sheets overlapped.

I arranged for a contractor to have the roof cleaned with a biocide to remove moss and other debris, then to apply heavy builder’s flexible mastic to the overlapping joints.

Chris Ennis, Property Doctor, Chartered Surveyor
Chris Ennis, Property Doctor

If water penetration continues, then a coat of proprietary water proofing barrier (Aquapol or similar) over the joints should further extend the life of the roof. This repair is not expensive or time consuming, but care should be taken if climbing on to the roof since asbestos sheets can be brittle with age. Always use crawling boards. With good fortune the complete renewal of the roof might be delayed by 5 years or so.

Asbestos disposal regulations allow any domestic householder to dispose of reasonable quantities of ACMs without charge if they are double wrapped in plastic sheeting prior to consignment to a local tip with facilities to collect this hazardous waste. – I believe Shoreham amenity site is the nearest. However, if a building contractor removes the waste, a charge will be made.

Chris Ennis FRICS is a Chartered Surveyor Tel: 01903 261217 email: surveyor1@talktalk.net www.propdoctor.co.uk