A structural engineer is warning the government's latest review of building rules cannot hope to address severe problems in the construction industry.
This follows the evidence from a concrete scanning company that hundreds of major buildings have not been built according to plan.
Auckland engineer John Scarry has written to Prime Minister Jacinda Ardern today to amplify warnings he has made for almost two decades.
RNZ has also been contacted by two industry insiders who recount witnessing poor work that would have compromised buildings' strength.
Mr Scarry said the poor construction carrying on resulted from "100 percent legislative and bureaucratic failure" in the last three decades.
He dismissed the review of building laws and regulations underway by the Ministry of Business, Innovation and Employment as an "industry group hug".
"Legislative and bureaucratic changes to what is fundamentally not a legislative or bureaucratic problem will not cut the mustard. The problem is one of technical competence and ethics, or more precisely, a widespread lack of them," he said.
The Auckland engineer co-wrote a warning to the government earlier this year, but said all this elicited was the assurance that the "ministry will handle it".
RNZ has also been contacted by an industry insider involved in structural steel installations at Hobsonville in west Auckland.
"I have seen in situ pours of concrete walls and concrete slabs done very poorly" by a company that marketed itself as a specialist, the person, who RNZ agreed not to identify, said.
"The problem I see often is that the work is hard and dirty and probably doesn't pay very well, therefore they only attract workers of lesser skill and knowledge or experience ... they are probably one among many [problems]."
Another insider said he had witnessed lots of poor work with concrete, including it commonly not being compacted properly to ensure there were no voids, and it is left for too short a time to strengthen before loads were put on it.
"I spoke with one reinforcing placer, working on a multistorey apartment building, who rang the boss on Saturday to say he would finish the reinforcing on Monday, only to arrive then and find the concrete had been poured."