Up to 36,000 quake-damaged Christchurch homes may be tested for asbestos providing a bonanza for companies in the asbestos testing and removal business.

Asbestos fibres are a potential health hazard because of their association with cancer and were used building materials, such as textured ceilings, cladding, roofing, and in backing for older floor tiles and vinyl. The material normally poses little risk unless disturbed - which is increasingly an issue in Christchurch were so many damaged homes are being repaired or demolished.

Fletcher EQR is managing repairs on about 80,000 Christchurch homes and says all houses built between 1940 and 1990 which have damaged ceilings will have to be tested for asbestos.

EQR says the figure of 36,000 is consistent with estimates based on historical building data but it is too early to say how many homes will return positive results.


However industry sources suggest about half the samples being collected (often more than one per property) are positive, and the number of homes needing remedial work on asbestos could run to thousands.

Capital Environmental Services (CES) in Wellington does bulk asbestos testing and consultant Linda Dwyer says Christchurch samples now make up 80 per cent of the company's work load, whereas previously it was only 5 or 10 per cent.

Over recent weeks CES has received between 40 and 60 samples a day from Christchurch buildings, mostly residential properties, and so far this year just under 40 per cent of textured ceilings have tested positive for asbestos.

Chemsafety collects samples and checks homes to ensure they are safe to reoccupy once asbestos-related repairs are completed.

Company owner Mike Gray says work in Christchurch has increased markedly and of the 200 samples a week sent to Auckland for testing, about half show asbestos is present. "The textured ceilings that look like oat meal, 80 per cent of them come back positive for asbestos."

Removing damaged asbestos ceilings costs between $90 and $130 per square metre and one company specialising in this work has quoted to treat close to 500 homes since the quakes started almost two years ago.

Another company, Canterbury Heating Ltd, has about 150 houses on its books awaiting attention and owner John Wilder says the scale of the work is mindboggling. "Nobody really realised what a huge job we have got in front of us, it's thousands of houses."

EQR has four options for dealing with damaged ceilings containing asbestos. They include covering with plaster board (encasement), repairing (raking out, re-plastering and painting), sealing with paint or resin, or complete removal and replacement.

Wilder says the disadvantage of encasement is that it poses a future risk to DIY homeowners or tradesmen unaware asbestos is present. "If you cover it up with gib board and an electrician drills a hole to put a down light in and gets asbestos on himself, he's going to go ape."

In May Canterbury District Health Board CEO David Meates raised concerns about encasement because he said nailing up batons to erect false ceilings disturbed asbestos-containing material and this method also covered up a significant issue which would still need to be addressed at some stage in the future.

The Labour Group of the Ministry of Business, Innovation and Employment has talked to contractors about asbestos at hazard identification workshops run in Christchurch.

Labour Group Christchurch Service manager Margaret Radford says ideally asbestos should be removed from buildings; however there are situations where encapsulation, sealing or covering may be acceptable alternatives. "We do not have any reason to express concern over the standard of work done to date."

Chemsafety's Mike Gray says an asbestos register is needed so buyers of commercial or residential buildings can establish whether asbestos is present and where it is located.

EQR provides homeowners with records of repair work carried out on quake-damaged properties, but the Christchurch City Council says owners are not obliged to lodge copies of those documents on council property files where they can be viewed by prospective buyers.