A steel quality expert is questioning whether the rules are tight enough around thousands of tonnes of Chinese steel going into the country's tallest residential skyscraper.
Seascape Apartments on Customs Street, at 52 storeys and 187 metres high, is being built by a Chinese contractor, using structural steel manufactured in China.
New Zealand's strict seismic steel standards make welding beams and frames difficult.
Australasian Certification Authority for Reinforcing and Structural Steels (ACRS) executive director Philip Sanders said problems with tainted steel supply worldwide meant his organisation was not coy about asking questions about the steel supply for the Auckland project.
It was crucial to ensure testing at every stage - of the product, the manufacturing processes, and how it was supplied.
"It really needs to be [an] independent party that sets the test plan ... for international best practice it should not be under the auspices or control of the [steel] supplier."
Random testing was also needed to ensure inferior product was not sneaked into the supply chain after an order had left the factory gates, Mr Sanders said.
Industry insiders have suggested to RNZ that this was what occurred over 1600 tonnes of substandard Chinese steel that had to be binned at a Waikato highway project in 2016; the Transport Authority and contractors have never provided information about what happened in that case.
At Seascape Apartments, supplier JingGong Steel is in charge of the inspection regime, alongside the main contractor, China State Construction.
JingGong is not ACRS certified but certification is not compulsory.
While some in the industry play down ACRS authority and have suggested it was used to protect Australian steelmakers from Asian competition, the certification was the first thing Auckland Council looked at in its new rules.
The Building Code allows for multiple ways to get approval. Whichever way is taken, council independent oversight will apply to JingGong and Seascape.
A council spokesperson said finished steel samples would be sent to a variety of testing providers, including some in New Zealand.
"JingGong Steel is to provide all the logs and details of testing undertaken."
Mr Sanders said there would normally be an independent person unconnected with the supplier independently monitoring the construction process, materials and testing.
"If there proves to be a problem, would there be any incentive for the supplier's agent on the site to not do what they should do?"
Auckland Council had recently put in more checks and balances on structural steel supply; also, tighter nationwide requirements around structural steel come into full force in July, under changes made by the Ministry of Business, Innovation and Employment to outdated 20-year-old parts of the Building Code. Thirdly, Philip Sanders said China State Construction would know how to avoid pitfalls on the steel supply side in China, better than a New Zealand contractor could.
The 178-metre tall Pacifica building is going up in Auckland soon and is being developed by Chinese-based Hengyi Pacific, using Australian contractor Icon.
The steel strand for the building was coming from a mill in China called Silvery Dragon, which was certified by ACRS and with a proven track record in New Zealand, the council said.
Mr Sanders said he would hold more talks with council about the role of ACRS role in steel rules.
Seascape developer Shundi Customs has not responded to RNZ's repeated requests for comment.