Assessing city buildings major exercise

Looking out on to the new University of Otago's clinical services building in Dunedin and the...
A general view of the Dunedin cityscape looking towards North Dunedin. Photo: Craig Baxter
The DCC is set to begin an 
assessment of potentially earthquake-prone buildings in Dunedin. Grant Miller reports.

A fresh assessment of potentially earthquake-prone buildings in Dunedin will soon begin.

Identifying them all and working out what needs to be done to improve them could take about 10 years. Fixing them could take much longer.

Major changes to the way earthquake-prone buildings are identified and managed have resulted from a 2016 law change that brings a consistent approach across New Zealand.

Dunedin City Council building solutions manager Paul Henderson says some companies may carry out...
Dunedin City Council building solutions manager Paul Henderson says some companies may carry out seismic upgrades sooner than they need to, because tenants could need buildings to achieve certain earthquake ratings. PHOTO: SUPPLIED

Dunedin did not need to act immediately because the city is not in a high-risk seismic zone, but property owners will soon have to grapple with the issue.

Dunedin City Council earthquake-prone building compliance officer Peter Brookland took on his role last year.

"There has been a lot of initial work completed around setting up procedures and guidance documents," he said.

Mr Brookland said a lot more work was now needed, to review information already provided as part of voluntary seismic-strengthening activity and from previous work the council had done about earthquake-prone buildings.He said he was looking forward to working with building owners to get durable results for them and their tenants.

The Building (Earthquake-prone Buildings) Amendment Act classes areas of New Zealand as low, medium and high-risk and sets timeframes for identifying and taking action to strengthen or remove earthquake-prone buildings.

Buildings deemed earthquake-prone in Dunedin will be rated and added to a public register.

If the council considers a building to be earthquake-prone, its owner will be expected to provide an engineering assessment within a year.

Dunedin City Council building solutions manager Paul Henderson said most of Dunedin was within a low-risk seismic zone but a small rural area west of Middlemarch was in a medium zone.

Building owners in medium zones have 25 years to complete seismic building work after receiving notice their buildings are considered earthquake-prone.

Those in low-risk seismic areas have 35 years to produce solutions.

"While this could be seen as a long period of time, in many cases commercial decisions to do the work earlier may be taken as tenants may require buildings to achieve certain earthquake ratings," Mr Henderson said.

The law change made the Dunedin City Council’s own earthquake-prone building policy redundant.

Mr Henderson said some building owners volunteered engineering reports to the council but the law required engineering assessments to be done with a standard methodology.

The council would write to building owners who supplied engineering reports, to give them the chance to check if the reports were written using the new system.

The council would also start identifying higher risk potentially earthquake-prone buildings within the low-risk area.

"In these cases, we will write to the building owners, requesting an engineering report to be completed," Mr Henderson said.

All building consents that include voluntary seismic upgrades will be reviewed according to the new methodology from January 1 next year.


Earthquake prone

What is an earthquake-prone building?
A building, or part of a building, is technically defined as earthquake-prone if it will have its ultimate capacity exceeded in a moderate earthquake and, if it were to collapse, it would do so in a way that is likely to cause injury or death to people in or near the building or damage to another property. More succinctly, an earthquake-prone building is one judged to comply with less than 34% of the new building standard.
Source: Ministry for Business, Innovation and Employment

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