Building and construction minister Chris Penk announced changes to the earthquake-prone building system yesterday, saying the current system for assessing and managing seismic risk in buildings was placing an overwhelming financial burden on owners.
The new system had a focus on keeping costs proportionate to the consequences of building failure.
The old system of percentage risk had been dumped and replaced with four levels of mitigation.
The change in the seismic zone for Dunedin came from new seismic hazard research by GNS Science carried out in 2023.
University of Otago associate professor and Centre of Sustainability director Caroline Orchiston said the seismic readings highlighted faults around Dunedin.
"That’s mainly because we have these active faults around Dunedin that are pretty risky for us," she said.
"It sounds scary that we’ve gone to medium. But in terms of building risk, the other changes that they’ve brought in really do help us."
The new legislation was focusing on the worst and most risky buildings only and quite a few of the earthquake-prone buildings on the register would come off it.
Many of the small towns in the south would no longer be bound by the legislation, she said.
"It is a huge boost. It means the likes of your old theatre in town or your town hall that needs work, as long as it’s under three storeys high, you’re not going to have to do the strengthening work."
The old system was just capturing too many buildings as being earthquake-prone.
It was a balance between safety and cost, she said.
"You want to look after people, but you’ve got to moderate the cost because we haven’t got billions of dollars to spend on this. So you’ve got to target your investment. We want to worry about the most risky buildings."
The change to medium risk meant there would be 150 buildings in Dunedin in that zone, with possibly more to come.
Architect and heritage developer Stephen Macknight, of Dunedin, said there were some good bits in the proposal, but he wanted to see how it would all work out.
"There are a lot of people who have been spending a lot of money, and they could well find themselves frustrated by the rules all being changed all of a sudden again."
He did think the old system was too blunt and the changes should help small towns.
"It left people in some of these buildings with no chance of ever being able to afford to or do anything with their buildings, and you end up destroying every small town if you’re not careful, which you have seen happening around the place."
No-one had been badly injured or killed in low seismic zones, he said.
"So, you know, it is a huge cost burden without evidence that it’s cost effective in terms of risk."
He was not concerned he had spent money to strengthen buildings which would now not be able to be done.
"So, it’s not going to stop the strengthening happening. It’s just not forcing it, perhaps, so much on people when it’s not an appropriate building or an appropriate time. So, that could well be a good idea."
The idea that a chimney being at risk led to the whole building being classed as a risk did not take into account that different areas of buildings had different risks, Mr Macknight said.
At a glance
Earthquake-prone building changes.—
— Percentage national building standard is dumped.
— Unreinforced masonry building with unsecured facades and walls facing public areas will be automatically deemed earthquake-prone buildings.
— Concrete buildings of three storeys or more will be assessed for earthquake standards.
— There will be no earthquake-prone buildings in Auckland, Northland and the Chatham Islands.
— Coastal Otago, including Dunedin, will shift from a low to medium seismic one.
— Four levels of mitigation — full retrofit, targeted retrofit, facade screening or remain on the earthquake-prone building register.
— Deadlines to get earthquake proofing work done will become more flexible, offering up to 15 years to complete work.
— Fewer buildings will be classed as priority buildings.
— Expected to save more than $8 billion.
