The government and a key agency are at odds over what's being called a "broken" and "failing" building products assurance scheme.
The accreditation agency JAS-ANZ, which runs CodeMark from its base in Australia, has rejected key findings of a review that faults its expertise and monitoring of the flagship CodeMark scheme.
However, officials are using that self-same review to overhaul the scheme.
Construction industry players said CodeMark's failings are eroding efforts to introduce innovative building products.
"We suspect that CodeMark is having implications for housing affordability because it means we don't necessarily have the cheapest and best product on the market," Matt Paterson of the Property Council said.
CodeMark was expensive, slow and uncertain: "A product can be declined after sitting in the bureaucracy for years, with no explanation."
"We've known about the bureaucracy for a long time because our members have been struggling with CodeMark - we were not aware of the quality issues until [RNZ's] reporting on it," Mr Paterson said.
"That makes it even worse, that there's these huge bureaucracies that aren't actually delivering quality products."
RNZ wanted to ask the Ministry of Business, Innovation and Employment (MBIE), which owns CodeMark, how JAS-ANZ's rejection of the review might impede its ongoing attempts to overhaul the scheme, but it declined to be interviewed.
The ministry had the review for 13 months before releasing it due to an RNZ request this week.
It would have been nice to see it sooner, said Mr Paterson.
"Some of our members will be concerned that the products that they thought were quality may not have the quality that they wanted.
"The liabilities if there are any, are going to have to lie either with the government or with councils because people took these certificates in good faith."
The ministry said it had already acted on some of the review's recommendations, including increasing resources for JAS-ANZ to monitor CodeMark.
'We were never engaged as technical experts'
But JAS-ANZ chief executive James Galloway did not admit to any shortcomings in that monitoring in the first place.
"There are definitely instances of deficiencies [by certifying companies] but the system is set up to detect and correct them," he said.
Dr Galloway also rejected the review's suggestions that JAS-ANZ lacked the required technical expertise in the New Zealand building code and construction industry.
"I just don't necessarily accept the assertion made in the report.
"We were never engaged as technical experts ... what we bring is understanding of the certification process at a national and international level."
JAS-ANZ hired outside experts where it needed them, Dr Galloway said.
He also took issue with the review presenting JAS-ANZ as though it was the MBIE-appointed manager of CodeMark.
"That's not true... I realise it comes out of that report but that's never the basis on which we were engaged... We are not the managers of the New Zealand scheme."
It does manage the Australian version of CodeMark, but that has already been overhauled after its shortcomings were identified six years ago.
One CodeMark certificate issuer, CertMark of Queensland, is under particular pressure from a ministry audit of its certificates for aluminium composite cladding - a semi-combustible type similar to the fully combustible type used on London's Grenfell Tower.
CertMark said CodeMark was too slow, citing applications for certification for home prefabricated building systems that were in the wings waiting.
'Very professional'
But as for making JAS-ANZ improve its monitoring, CertMark's head John Thorpe rejected that.
"The current surveillance ... by JAS-ANZ is ... very professional and appropriate," he said.
"Adding of layers of bureaucracy is only going to burden all involved with paper work to verify what is already adequately verified."
Like the Property Council, the Building Industry Federation had not seen the MBIE-commissioned CodeMark review before now either.
That's despite the ministry calling for the federation's input - as the industry body of products suppliers - into a wider review into product quality that began two months ago.
They had hints all was not well with CodeMark, said the federation's Bruce Kohn.
"It certainly does matter because there's been an increasing tendency of building consent authorities to question the validity of products covered by CodeMark."
Despite being in place for nine years, CodeMark has only issued 135 certificates, fewer than 15 a year, among the tens of thousands of building products.
Mr Kohn and Mr Paterson's groups, and the Residential Development Council, all point to this low market penetration as proof of how little the scheme has been helping get cheaper and better products into New Zealand, when the need for a robust and widely used quality assurance scheme has never been higher.