A complaint about the safety of a common earthquake bracing system has been rejected by officials, but has exposed weaknesses in the engineering system.
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Investigations have been going on for more than two years into an allegation - from a commercial rival of a manufacturer - that a common type of brace which is used to anchor ceilings in schools, hospitals, and supermarkets was not tested properly, or strong enough.
Officials have rejected the allegation but have also now asked the company to review its testing, and are suggesting that finding solid ground when it comes to seismic design is difficult because it relies so much upon engineers' individual opinions.
Engineers were left to interpret information about the steel brace straps that had the "potential to create confusion", the Ministry of Business, Innovation and Employment (MBIE) wrote in documents released under the Official Information Act.
In communications to the manufacturer of the braces and its major supplier, the ministry said the information "refers to strengths and safety factors that are for a design method that is no longer used to design buildings in New Zealand".
The ministry and the Commerce Commission got a structural seismic expert to check the bracing.
"We are satisfied that there is no apparent material safety concerns posed by this product," the ministry said.
It "is neither dangerous nor unsafe".
The allegation was that "dynamic testing" of the brace was not being done.
"Dynamic tests would normally be used to show their performance under dynamic loading," the ministry said.
It has asked the company to review if it was doing enough testing to meet the Building Code, and to review its technical information to ensure it was "accurate and consistent".
A warning or a ban was not needed, MBIE concluded.
But it has asked Engineering New Zealand to get involved, to try to get a better consensus among engineers about what they need to know about the testing and use of critical safety products.
"Conflicting views from experts dealing with seismic bracing systems are understandable," it said in the letters.
"Complaints we receive about these systems reflect a range of decisions that engineers need to make."
Meeting the Code depended as much on the competence of each engineer as it did on the product information, it said.
"Much of the ambiguity about seismic bracing systems can be attributed to the way engineers interpret and use the product information provided by suppliers and manufacturers."
It was this high level of ambiguity that had earlier stymied the Commerce Commission.
It could not decide if any fair trading laws were breached in the bracing case, partly because of the "lack of clarity around the compliance requirements for these types of products", the ministry said.
The commission then passed the ball to the ministry, hoping to get more clarity.
The ministry has pinned its hopes on engineers reaching a consensus that could then be used to "clarify or revise" the Standard (NZS4219).