Buildings in Wellington and Auckland subject of fresh seismic inspections
Hundreds of office staff across Wellington and Auckland are unknowing participants in a secret trial into whether parts of their buildings could collapse in a major earthquake.
Seismic testing of about a dozen buildings in each city has been done for the Ministry of Business Innovation and Employment – but the identity of the buildings is being kept under wraps.
The survey of "random" buildings, of varying ages, was prompted by earthquake damage to Wellington's BNZ Harbour Quays office block in 2013, after a 6.5 magnitude quake shut down the CBD.
The quake caused air conditioning ducts, wiring tracks and pipes to break loose, and ceilings collapsed on to desks.
The report for MBIE, which is understood to be in draft form, is believed to have found only 5 per cent of the buildings surveyed were up to scratch.
Industry insiders are speculating the stock-take will be so damning that its fallout will prove bigger and more expensive than the leaky homes fiasco.
An MBIE spokesman said the buildings in the survey were chosen at random, and not because there was any perceived seismic risk, so he would not give locations.
"The survey is set up specifically to protect the identity of buildings where owners and tenants have agreed to participate."
Neither the ministry nor the engineering consultancy conducting the tests required the inspections to be kept confidential from staff in the buildings. It was the owners' decision as to whether to inform staff if they wished to do so.
The survey was done to check the "seismic restraint of non-structural elements" – such as ducts, wiring tracks and pipes.
"There were numerous anecdotes of non-compliance of the extent of seismic restraint of non-structural elements and observations of poor seismic performance, but there was little actual evidence, which the survey intended to provide," the spokesman said.
MBIE commissioned the survey after hearing numerous tales of "non-structural elements" being damaged in quakes, but having little evidence to back up those anecdotes.
Wellington was picked because of its seismic risk, and observations of damage from previous earthquakes. Auckland was chosen for its large number of commercial buildings.
Wellington City Council was contributing to the survey on a "building consent authority perspective", which included dealing with earthquake performance of existing buildings, as well as implementing building control legislation.
It helped the survey team contact building owners, and access property files held by the council.
Council building resilience manager Steve Cody said a lot of non-structural elements were outside the Building Act, in regard to what councils looked at when issuing consents.
The survey was small, but would give a good indication and a better understanding of current stock, he said.
"It may be decades since some buildings have been upgraded. It's not about finding fault, this is about a stock-take and understanding of the current conditions."
He believed the survey looked at 12 buildings in Wellington and 12 in Auckland.
"Once the stock-take is done and we have a better understanding, we will then look if we need to expand the size of the survey and look at more buildings."
Depending on the outcome, the council might consider giving better guidance and advice to the construction sector on things it needed to look at when installing ducts and pipes.
The project was a response to recommendations made by the Canterbury Earthquake Royal Commission, and was part of a large programme of work MBIE was undertaking to improve the seismic performance of buildings.
The results would help the ministry understand if more work needed to be done, its spokesman said.
The March issue of the New Zealand Society for Earthquake Engineering newsletter says there was a raised awareness of the seismic vulnerability of non-structural elements and the costly consequences when they performed poorly.
"Impacts on business continuity due to the damage of non-structural elements has been identified as a major cost and disruption issue in recent earthquakes in New Zealand," the newsletter said.
"Clearly improvements in performance under earthquake loads will yield benefits to society."
THE BNZ EXPERIENCE
* The BNZ's Harbour Quays building, near Wellington's CentrePort, which was opened in 2009, had to be evacuated after the 6.5 magnitude quake in July 2013.
* Air conditioning ducts, wiring tracks and pipes broke loose, ceilings collapsed on to desks, and water from broken pipes soaked carpets, electric wiring and office equipment.
* Nobody was hurt, as the quake hit on a Sunday, but it took six months before the first staff returned. It was 15 moths before they were all back in the building.
* The bank estimated the cost of fixing the building and relocating staff ran to about $10 million.