Builders stung to action on house rot

By GREG ANSLEY

The building industry has called for a tough new national inspection system after revelations that many of the country's new homes are in danger of rotting inside because of design and workmanship failings.

Almost two-thirds of the new homes surveyed in one Auckland study leaked.

Failures in cladding and framing revealed by the Herald on Saturday may also open the door to litigation as homeowners seek redress.

Under statutory building codes, cladding should be durable for at least 15 years, and structural framework for 50 years.

Liability for repairs could cover not only builders and sub-contractors but certifiers and local authorities.

Building industry officials said yesterday that the causes went well beyond the use of untreated kiln-dried timber and extended throughout a cut-throat supply and construction chain.

They also said existing inspection and certification systems were not adequate to deal with dramatic changes in the materials, design and construction of houses over the past 10 years.

The potential scale of the problem was shown in research presented to a Certified Builders Association conference at the weekend.

It was told that a census of 287 pre-purchase inspection reports on Auckland houses between 1996 and 1999 found 60 per cent leaked to some extent.

The owners of one two-year-old house worth $450,000 faced repairs estimated to cost $150,000.

Building industry officials said that although the replacement of chemically treated timber by kiln-dried wood had been blamed for the increase in rotting houses, the real causes lay in leaks and inadequate regulation.

Over the past 10 years, they said:

* Designs had moved away from water-shedding details such as eaves.

* New cladding and insulation hampered drying by air circulation inside the walls.

* Window flashings increasingly relied on sealants, often with lives of only two or three years.

The industry also blamed intense competition that more often than not placed cost ahead of any other consideration and encouraged the use of cut-price contractors and cheap imported materials.

Dr Mick Hedley, a project leader with Forestry Research at Rotorua, said more research was needed into the impact of new designs, materials and techniques.

But, he said, no single body was able to coordinate or pay for complex new studies into waterproofing homes.

The Hamilton conference was told that problems existed with untreated kiln-dried timber because it was being used in high leak-risk areas or where dampness was likely.

But the Auckland Master Builders Association president, Eric Miller, said lack of attention to design detail and intense competition contributed to the problem.

He also said that because of dramatic changes in the industry, new and increased inspections were needed.

Rose McLaughlan, president of the Auckland area Building Officials Institute, said inspectors were hampered because framing was often clad before inspection and certifiers had to rely on statements by contractors.

"We need to say 'stop' and go back look at the entire inspection system," she said.

"I think all buildings need something like a warrant of fitness and the regulation of all tradespeople involved in housing construction."