A government taskforce is leading an inquiry into the scale of the leaky home problem, which is something Building and Construction Minister Maurice Williamson said was bigger than he had imagined.
"The best estimate we have currently is that the repair bill will be about $3.6 billion -- a huge number," he told Build magazine. "We think that's about 20,000 properties."
Mr Williamson said as part of the drive to protect those getting houses built, a warranty insurance scheme would be introduced to ensure they were fit for sale.
Changes to building regulations also mean houses built in the last year are unlikely to suffer from leaky home syndrome.
Mr Williamson said efforts to try and solve the leaky home disaster to date were not satisfactory.
"It's just dreadful. We are going to completely revamp the whole process because the whole weathertight resolution process so far has seen huge chunks of money go into the hands of lawyers and litigation and tribunals and almost nothing going into fixing the rotting buildings," he said.
The warranty scheme was likely to be done through builders or insurance companies.
Mr Williamson last month said that on top of the known extent of the leaky homes problem, there would be further houses yet where issues hadn't surfaced.
He said the focus of the Weathertight Homes Tribunal investigating the problem needed to shift to coming up with fixes instead of paying fees to lawyers.
Problems with design, product, cladding, low skilled workers, rules and checks were all to blame in different houses, Mr Williamson said.
