More than 150 building owners have opted to shell out thousands of dollars in a bid to reconsider new earthquake ratings in Auckland.
After earthquake assessment legislation was passed last year the Auckland Council identified 1800 buildings thought to be below code.
Since October it's been contacting owners and giving them a choice - accept the rating, or get a second opinion.
The director of engineering consultancy firm EQStruc, Peter Liu, said they were dealing with at least a dozen seismic assessments each week.
"It's definitely been quite a busy couple of months, and also end of last year. Even in the past we've been doing a lot of assessments already for building owners. I think we're just seeing more a continuation of that with the recent legislation changes."
Those changes came into effect last July with the government introducing new ways of identifying and managing earthquake-prone buildings.
A building is considered earthquake-prone if its seismic strength is less that 34 percent of the design standard for a new building in the same place.
Auckland Council has found 1800 buildings that fit the bill, and since late last year, has been progressively contacting their owners.
Patrick Cummuskey leads the council's earthquake prone buildings programme and said so far three local boards had been contacted, starting with the Puketāpapa area.
"We had a reasonably good level of interaction from owners. A number of which accepted the rating, and around about 15 to 20 percent came back to us and said they would like to get a new assessment done. Then that pattern has developed as we moved into Devonport, Takapuna ... and then we've got the rest of the city coming up."
Mr Cummuskey estimated around 160 building owners had chosen not to accept their original assessment so far, opting instead to seek their own evaluations.
The council itself had also sought re-evaluations for some of the 100 earthquake prone buildings it owns.
It's not cheap - while initial evaluations can cost just a few thousand dollars, full detailed assessments can be in the tens-of-thousands.
Mr Cummuskey said commercial drivers were the likely cause.
"We have banks, insurance company's, and financial institutions wanting to see buildings with good ratings.
"Tenants as well tend to be in the building, that to them it looks like we've performed well in any sort of event, so if a building owner is wanting to get the finances that they need, to get the tenants that they need, it is probably going to be in their best interest to have the closest reflection possible of a good score on their building."
Property Council head Connal Townsend said for many owners it would be part of their due diligence.
"It's going to give some certainty, while secondly also they might be lucky that the detailed engineering assessment might say, well the building's a bit stronger than the council thought, but thirdly it's also going to give them some opportunity to start to budget for some remedial work that has to be done."
Mr Townsend said despite the cost of assessment and the subsequent repairs, it often it paid for itself in keeping the value of the building and ensuring tenants were happy.
Because the risk of an earthquake is low in Auckland, building owners have up to 35 years to do remediation work.
The Auckland Council said it was important people understood earthquake prone didn't mean the buildings were unsafe to use.