Masterton Town Hall. PHOTO/EMILY IRELAND
New government advice shows councils could have left earthquake-prone buildings open while plans were made for their futures.
The Masterton municipal buildings, which include the town hall and former council offices, were closed in June 2016 after a preliminary assessment that they were earthquake-prone.
The building was added to the Ministry of Business Innovation and Employment’s [MBIE] earthquake-prone buildings register in August 2018, with an earthquake rating of less than 20 per cent.
Masterton District Council chief executive David Hopman said the advice at the time from engineers was that the amount of work needed to mitigate the risk in the auditorium was similar to that of rebuilding it entirely.
“The council at the time considered that without this mitigation, the risk of allowing the public into the building was too great.”
However, last month MBIE published guidance that most seismically vulnerable buildings were not imminently dangerous and could remain occupied while seismic remediation work was planned, funded, and undertaken.
MBIE said the guidance addressed “common misconceptions around how the New Building Standard [NBS] should be used” and clarified there was no legal requirement to close a building based solely on a low NBS rating.
MBIE building performance and engineering manager Dave Gittings said that compared to most business-as-usual risks, earthquakes were a low probability, and occupancy decisions needed to consider the likelihood of an earthquake and temporary mitigation measures that could be used.
“An NBS rating is not a predictor of building failure in an earthquake, and buildings with low NBS ratings are not imminently dangerous,” he said.
“Understanding the relative vulnerability of different building elements, potential consequences of failure of these elements, and options to mitigate that risk, is more important than the overall NBS rating for a building.”
MBIE said buildings with an NBS percentage of less than 34 per cent were earthquake-prone, and building owners were required to remediate their buildings within a specific timeframe, but buildings could remain occupied during that time.
New buildings were designed with a one-in-one-million annual death risk due to earthquake, compared with an estimated one in 700,000 for flying a plane or one in 20,000 for driving a car.
The estimated death risk in a building under 34 per cent NBS was about one in 40,000 to 100,000.
Hopman said the MBIE guidance would not impact the council’s decision to close the town hall and municipal buildings.
“The well-being of staff and visitors to the building was given priority in the decision to close the building. This remains the case. The same approach was used when making the decision for Wairarapa Archive staff to move out of an earthquake building last year.
“The assessment for the municipal buildings has not changed, and they will remain closed.”
He said elected members of MDC were yet to make a decision on the next steps for the building. – NZLDR
- Public Interest Journalism funded through NZ On Air
