About 9000 home owners will never receive compensation for damage to their leaky homes, leaving thousands of New Zealanders unable to repair or sell their properties.
A PricewaterhouseCoopers report issued yesterday estimates between 22,000 and 89,000 homes are affected, with a consensus figure of 42,000.
The review, commissioned by the Government, said only 3500 homes had had repairs done and about 9000 had gone beyond the 10-year legal liability limit period. Any failures that occur outside the 10-year period become the owner's responsibility.
Based on the figure of 42,000 affected homes, the report estimates the total repairs at $11.3 billion.
Philip O'Sullivan, a director of leaky homes specialist firm Prendos who was credited with bringing the problem to light, said the numbers were ball-park figures but realistic and the total costs were what he expected.
"But it's crystal ball-gazing - no one really knows."
John Gray, a leaky-homes campaigner, was pleased the report had been released. "The top end is more in line with what we believe, but it's a good basis for what we do next."
He said the report missed the point that leaky homes were more than just an Auckland problem - it was New Zealand-wide.
He hoped that whatever the Government decided to do it would include the homeowners caught outside the 10-year limit.