New 'leaky homes' standards not mandatory

11.45am - By SIMON RANDALL

Councils, builders and architects do not have to comply with new building standards, aimed at ending "leaky homes" problems.

Untreated timber can still to be used in internal framing in houses and in "low risk" outer walls under revised standards announced by Standards New Zealand (SNZ) and backed by the Building Industry Authority (BIA) today.

Although the revised standard specifies treated timber for framing external walls when that framing is behind certain cladding types, such as monolithic cladding systems, the BIA's official citation of the standards does not make them mandatory.

Designers and builders are free to deviate from the standards if they can satisfy local councils that buildings will be designed and built without being susceptible to rot.

The BIA hoped councils would use the new standards as a benchmark, authority chairman Barry Brown said today.

Although the BIA hoped the standards would see an end to leaky homes being built, the authority could not offer a "100 per cent guarantee", he said.

"If buildings are well built they'll survive, if they're not (well built) there's a good chance they won't," Mr Brown said.

Under the standards, untreated timber, such as douglas fir, can be used in walls deemed at "low risk" of leaking, such as brick veneer buildings. It can be used in low-risk floor framing, trusses and ceiling joints and interior construction.

But in a major change, untreated timber cannot be used in situations where there was "significant risk" it would get wet and therefore rot, SNZ general manager marketing Grant Thomas said.

The standards were "less conservative" than proposed, but comprehensive, Mr Brown said.

"The authority is not prepared to take risks with new forms of construction at the expense of home owners."

Timber must now be colour-coded to ensure builders can easily identify treatment levels, to reduce concerns about timber getting mixed up on site.

Under the new standards, the cost of building a low-risk brick house, which comprises a third of the market, would rise by up to $2000. But the cost of building a higher risk house could rise by $5000, Mr Brown said.

The BIA estimated the moves would benefit the economy by between $94 million and $1.1 billion over the next 25 years.

Last Friday, the BIA confirmed the standards would be cited as a means of compliance with the Building Code, taking effect from April 1 2004.

"Although a considerable number of designers and builders had already moved to using treated timber in some situations, the publication of these standards, and the BIA's decision to cite them, gives the whole industry clear guidelines on the appropriate use of untreated and treated timber in houses," Mr Thomas said.


The New Zealand Forest Industries Council (NZFIC) today welcomed the standards on use of treated timber, but remained concerned about standards for treated timber in external frames.

"It is good to have this matter resolved," NZFIC chief executive Stephen Jacobi said in a statement.

However, the industry was concerned the BIA was allowing use of untreated radiata pine and douglas fir behind brick veneer but required treatment in other situations, he said.

The decision was not justified by scientific analysis of the leaky homes problem.

Building methods, not materials, had been the proven "culprit" in leaky homes, Mr Jacobi said.

Mr Brown said the cladding standards aimed to give a second line of defence for frames against moisture if outer walls leaked.

Douglas fir forest owners and sawmillers have said they will continue to seek a judicial revue of BIA and SNZ decisions.


- NZPA