The country's leading supplier of aluminium composite panels for high-rise buildings has pulled out of the government's troubled CodeMark scheme.
The supplier, Symonite, said it has "simply lost faith in [the] ability and decision making" of Codemark, which the Ministry of Business, Innovation and Employment markets as the gold-standard of building product assurance schemes.
"In recent months, we have had cause to question the veracity of this scheme," Symonite director John Cobb said in an email to customers.
Last week MBIE suspended six certificates covering 13 types of panel, saying they lacked evidence of compliance with the Building Code.
A few days before this, RNZ obtained a review of Codemark which MBIE had not previously released. It found multiple fundamental shortcomings with the scheme.
This followed an audit prompted by the fatal Grenfell Tower fire in London a year ago, and multiple other fires around the world fuelled by panel products in high-rise buildings over the last few years.
However for at least two years, one critic has raised issues with CodeMark certificates.
John Cobb said Symonite was "extremely disappointed" its CodeMark certificates for two types of panel - Alubond and Symonite Reynobond FR - had been suspended.
That was despite providing MBIE with "extensive information", that came at a considerable expense to the company.
"We were encouraged by MBIE to participate [in CodeMark] and took part in good faith that this was a well administered and well managed scheme", only to end up questioning it, he said.
The audit "has not unearthed any evidence that our products are dangerous", Mr Cobb said, adding they were fully compliant with the Building Code.
CodeMark is voluntary, but is the only scheme that provides a certificate that isn't able to be challenged by council building consent officers.
"Further, there is no ban in place nor is there any connection to recent high-profile fire events like Grenfell," he said of the company's products.
The Grenfell Tower had panels of highly flammable polyethylene cores sandwiched between two aluminium sheets -- the panels affected by the suspension here in New Zealand have less-combustible cores.
Insurers in the UK are pushing to ban these on high-rises and Australia is making moves to crack down on any panel with a core of more than 30 percent polyethylene.
MBIE won't say if the Australian company that issued the suspended certificates, Certmark International, is being investigated.
Certmark has rejected criticism from the National Party's construction spokesperson. It said Andrew Bayley was incorrect to release a statement saying the panels had been "banned", when the temporary suspension was to give certificate holders the opportunity to address concerns.
The certificates for the panels could not specify exactly how panels should be safely used, so needed back up from fire engineers or other qualified people at the building site, Certmark said.
It has said that none of the FR panels would pass the new fire tests used in Australia, because of the burning debris that falls off them. However, New Zealand does not use these Australian tests, but a much older US test.