One of the country's biggest steel manufacturers has been selling critical earthquake-reinforcing mesh wrongly certified as having been tested by a top laboratory.
In fact, all the strength testing of the mesh has been done in-house by Steel & Tube itself.
It says the logo and contact details of the Holmes Solutions lab were inadvertently kept on the certificates from when the lab helped it develop its testing regime four years ago.
It cannot explain how that happened.
The top 50 stock market company has issued thousands of these test certificates to customers including major building companies.
Holmes Solution, which is based in Christchurch, is one of the few accredited testing labs for building products in the country.
Steel & Tube told Holmes Solutions about the certificate issue in the last three weeks.
RNZ News has five of the one-page certificates. Each shows Steel & Tube's logo at the top, with the logo, name and contact details of Holmes Solutions at the bottom. Directly above are the names of the person who did the test and the lab manager, and above that the test results.
Steel & Tube chief executive Dave Taylor said it was a mistake.
"We inadvertently continued to include their logo on these certificates. That was a mistake," he said last night.
"I don't know the number off the top of my head but there would be many thousands of them because there were many thousands of sheets of mesh. We only came across it last week ... maybe, maybe it does seem incredulous but that's the reality of it."
Mr Taylor said Holmes Solutions "understands" what had happened. Asked if there would be any compensation for the lab, Mr Taylor said he was "not prepared to discuss that".
"We all acknowledge that it would be better if the Holmes Solutions' logo was not on the certificates produced by Steel & Tube personnel.
"I think we accept that and we have apologised to Holmes Solutions for that, and it is removed and will not be on future certificates that are issued."
Asked what a mesh buyer would think about what the certificates with the logos on them meant, he said: "I can understand why some people may think that there's a degree of ambiguity there."
He said his firm's steel mesh, as tested in-house, was fully up to standard.
Steel & Tube is one of the top three mesh-makers in New Zealand.
The Commerce Commission is investigating two of Steel & Tube's rivals over whether they falsely advertised their quake-grade mesh.
The commission has said this imported mesh failed tests it conducted recently, but that has been hotly contested by the biggest of the two under scrutiny, Eurocorp.
Mr Taylor said that inquiry was a trigger.
"We were just checking out [our] own systems and procedures and that's how it [the test certificates] came to light."
Holmes Solutions has declined to be interviewed by RNZ News or comment about this.
Need to reassure customers - Master Builders
Registered Master Builders Association chief executive David Kelly told Morning Report Steel & Tube needed to contact its customers to reassure them of the product's safety.
"This is something that they need to take seriously. I think that they need to satisfy their customers, and potentially the consenting authority, that their product is fit for purpose.
"Now, how they do that - whether they do that through an independent testing is one way, or they may have another path - I put the ball back in their court to demonstrate that the product is fit for purpose."