A review has found the government's gold-standard scheme to approve building products, CodeMark, is seriously flawed.
The quality of CodeMark certificates is already in question after an audit criticised how they had been used to approve types of aluminium composite panel similar to those used on London's Grenfell Tower - which proved highly, and fatally flammable.
The review questions the competence and technical expertise of companies that issue CodeMark certificates.
It faults the scheme's owner, the Ministry of Business, Innovation and Employment (MBIE), and the manager it uses, JAS-ANZ.
There are 135 CodeMark certificates in total, often used to help innovative or complex products win over designers.
The certificates are meant to be so foolproof that councils must accept them as part of a building consent.
The ministry has marketed CodeMark since it began in 2009 as an "unchallengeable form" of evidence of compliance with the Building Code that gives companies a "marketing advantage".
The review, carried out by Deloittes for MBIE, was completed in June 2017 but only released now, after an Official Information Act request by RNZ.
A key focus was the "level of competency" of the bodies issuing the CodeMark certificates and how the ministry and the scheme's manager JAS-ANZ were "assessing and monitoring that competency", the review said. "And, in particular, whether JAS-ANZ has sufficient technical expertise in the New Zealand Building Code and building environment to undertake the assessment and monitoring of competency."
The Australian building regulator discovered CodeMark's inadequacies six years ago and has been overhauling its version of the scheme ever since, and has almost finished that.
MBIE said it was still working on an overhaul in New Zealand and would seek feedback, due in September, and change the scheme's rules by next March.
The CodeMark review said councils had the lowest levels of confidence in the scheme, partly due to "perception", but also because of errors in some certificates or ones with so little information the council could not be sure a product was up to scratch.
Product manufacturers had the highest confidence in CodeMark, the review said.
Industry players RNZ has heard from suggest there has been widespread scepticism about CodeMark's quality for a long time, but at the same time they echo the review's assertion that the industry sees the potential for the scheme to speed up consenting and open a path for innovative products.
If the draft regulations issued in September did not address the real problems, "all bets are off", one industry consultant told RNZ.
The ministry gave a statement to RNZ earlier this month when questions were raised about the CodeMark high-rise cladding certificates.
"The current work MBIE is doing ... is in response to recommendations made by Deloitte to ensure that the scheme is fit for purpose," it said.
"The project is looking at regulatory and operational changes ... broader legislative changes for product regulation and assurance and the CodeMark Scheme are being considered as part of the review of MBIE's wider review of building product regulation and assurance systems, also underway.
"MBIE has been working closely with [JAS-ANZ] to clarify roles and responsibilities ... as well as seeking agreement to key procedures and processes, and monitoring and reporting requirements."
The wider review it refers to comes a year after a similar review, initiated by the previous government in 2016, was completed, with no substantive changes made.