Plans for what will be the country's tallest apartment tower in Auckland are stuck in a dispute over whether a single stairwell for its top 11 floors is good enough in an evacuation.
This comes as fire rules for tall buildings nationwide are being tightened (PDF, 1.2MB).
The Grenfell Tower fire in London, and fire safety failings at all 75 other UK high-rises checked in its wake, has put a focus on tall building safety worldwide.
In Auckland, the council has called in the Ministry of Business, Innovation and Employment (MBIE) to make a ruling on the fire safety design for the 52-storey 187m tall Customs Street Residential tower.
The project's architect, Brad Luke, said it had two stairwells - up to a height that he wouldn't specify - and then a single one for the penthouses on top.
He said its design drew on evacuation designs that might be unfamiliar in New Zealand, but were proven internationally.
Current fire regulations allow a single stairwell in 60m and even 100m-plus buildings, as long as the stairwell is pressurised to keep out smoke and other fire safety measures provide back-up.
Massachusetts fire protection associate professor Brian Meachem said he would have expected New Zealand to go down the route the US has taken.
"We as a minimum require at least two means of escape from every floor ... even above two or three storeys, and as you go higher and have a larger occupant load you may be required to have even three means of escape or four."
That was based on experience in major high-rise fires, such as the MGM casino fire that killed 85 people in Las Vegas in 1980, and the 9/11 evacuation problems at the World Trade Centre.
In New Zealand, the fire regulations were overhauled just five years ago, followed by two years of additions explaining the rules, but the overhaul has not yet managed to properly address issues around tall buildings.
The latest MBIE discussion document, which is currently out for consultation, says the regime "currently does not address building height risk".
"Part of that is you haven't had a lot of very tall buildings and so it hasn't been a big concern until recently. So I would look at [the proposed changes] as a very positive step by MBIE and others to get out in front," said Prof Meacham, who has advised the ministry about the changes.
He said the regulations here were almost as tight as in the US, and in better shape than Britain.
Concerns changes don't go far enough
But Society of Fire Protection Engineers president Geoff Merryweather said he was not sure whether MBIE had done a full risk assessment of the changes.
"The changes basically bring us back to where we were pre-2012."
He said the tall building changes would still allow apartment blocks from 25m to 60m high to have a single stairwell that was not pressurised, and to do without the sorts of extra protection enforceable on high-rises above 60m.
The complications of single stairwells include firefighters running hoses through them while people try to get out.
In the late-night Melbourne Docklands high-rise fire of 2014, people took twice as long to wake up and evacuate as expected.
Mr Merryweather said New Zealand buildings were not dangerous - but some of the designing, construction and consenting, and use of the lowest-cost fire engineering were.
With so many challenges, he said, the government needed wide input.
"The feedback I've had from members is that many of them can't be bothered replying to any consultation from MBIE simply 'cos they never listened in the past, therefore why should they waste their time."
Developers have until March before they would have to comply with the new regulations.
MBIE said in a statement it had worked with the whole industry on the changes.
The proposals in the discussion document would "provide clarity on design for tall buildings" using a particular verification method to comply with fire safety regulations, it said.
"This clarity is designed to remove any inconsistency in agreeing … methodology and assessment criteria for tall buildings."
Auckland Council has not yet responded to RNZ's requests for comment.