Southern buildings checked using imaging technology that has uncovered structural problems in 1100 buildings across New Zealand have not featured the same issues.
RNZ yesterday reported new imaging technology had revealed hundreds of major buildings nationwide had defective or missing concrete or reinforcing steel.
Wellington company Concrete Structure Investigations, using ultrasound technology developed with Crown agency Callaghan Innovation, was able to look up to two metres inside concrete columns, beams, walls and floors.
The company found critical structural parts were defective or missing in 1100 of the 1200 buildings they had scanned since 2016.
Problems included rusting reinforcing steel, voids inside concrete and load-bearing walls saturated with water.
Company director Jane Roach-Gray said the company had used the technology on 12 buildings in the Otago and Southland area.
The work had involved the likes of people checking their building piles, or owners of old buildings checking what amount of steel was in their concrete.
In one case corrosion was found, and repaired, and in another, more testing was required.
Ms Roach-Gray said the company did less work this far south, so it was difficult to say if other building might feature problems found further north.
She was "astounded'' and "appalled'' by their findings.
"The divide occurs between what's in the plans and what ends up in the structure,'' she said.
"Some key structural elements are not going in correctly or they're not going in at all, and of course, once they're covered up with concrete, we - any of us - don't know what's actually gone into the building.''
The weakened structures include apartment blocks, offices, public building, most constructed since the 1980s, and some new or still-to-be-finished buildings, including in Auckland, Hamilton, Tauranga, Hawke's Bay, Wellington and Christchurch.
The buildings cannot be identified for legal reasons.
A structural engineer warned yesterday the Government's latest review of building rules cannot hope to address severe problems in the construction industry.
Auckland engineer John Scarry wrote to Prime Minister Jacinda Ardern yesterday to amplify warnings he had made for almost two decades.
The RNZ reports on Concrete Structure Investigations findings also prompted a response 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% legislative and bureaucratic failure'' in the last three decades.
He dismissed the review of building laws and regulations under way 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,'' 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].''
- additional reporting RNZ
