Timber preservative passes test

A preliminary report says there is no evidence to suggest the spray-on preservative TimberSaver does not perform, but building experts are worried about the way products enter the market and about builders' knowledge of their use.

The report has found no basis for withdrawing accreditation of the boron-based surface coating.

But the month-long inquiry by the Department of Building and Housing highlights confusion in the industry about use of the orange-dyed product and its substitution for H1.2 timber, which is fully penetrated with boron.

The report recommends further investigation of the robustness of the product-testing and accreditation process used for TimberSaver.

Wood treated with TimberSaver, branded T1.2, was approved last year after the Government reverted to the use of treated framing timber following the leaky buildings scandal.

Building Officials Institute members polled in the inquiry reported no sign of the product failing, but noted it "has not been on the market for sufficient time to show any signs of failure".

They said builders had little knowledge of conditions of use, such as the need to have tins of the coating on hand to seal cuts, notches and holes.

The officials were also concerned about the practicality of conditions of use, including that the wood not be exposed to the elements for more than two months.

The inquiry was sparked by wood scientist Robin Wakeling's claims that the coating had not been sufficiently tested and would be prone to leaching when wet.

Building experts were concerned that the timber was being misrepresented as H1.2 wood and used for external framing.

National MP Nick Smith branded the product shonky and slammed the department's predecessor, the Building Industry Authority, for approving it.

Yesterday, TimberSaver manufacturer Osmose NZ called on Dr Smith to apologise for calling the product a "con" without evidence.

Osmose technical sales manager Terry Smith said the performance-testing and accreditation process undertaken by the company and the BIA was proven to be sound and correct.

He said the claims had caused unnecessary angst and uncertainty for homeowners and the entire building industry.

The company faced an arduous task to repair perceptions of the product and was disappointed the accreditation process would be subjected to further review by Branz, the Building Research Association.

Mr Smith said sufficient information about the product was passed from the manufacturer to the merchant, but from that point "things went astray".

"Information that builders use when using framing products seems pretty woeful."

Building surveyor Greg O'Sullivan said the preliminary report was thorough but highlighted considerable scope for improvement in the industry.

It remained a concern that the Building Industry Authority had allowed a product that did not meet the requirements of H1.2 treated timber for use in the same situations, he said.

"There were sound reasons to move to a level of full sapwood penetration and those reasons are the same today."

He said the episode sent a clear signal to the department and to the manufacturing and supply side of the building industry.

"An awful lot of people were given timber they didn't order."

National's Dr Smith refused to apologise, saying the report vindicated his concerns about testing, impractical conditions of use and communication within the industry.