Wellington’s buildings need to exceed the minimum standard set by the building code if the capital city wants to improve its resilience to a major earthquake.
So says California seismic safety commissioner and engineer Kit Miyamoto.
New Zealand’s building code is a “simplified checklist” where the 100 per cent new building standard (NBS) was the bare minimum that had to be met to save lives, but didn’t go beyond that, Mr Miyamoto told a group of Wellington building owners at last week’s launch of a Deloitte economic analysis into the Kaikoura quake.
What’s more, in an earthquake about one-third of buildings will perform better than the standard, about one-third in line with expectations, and one-third less than the standard, he said.
“That’s just not good enough. Society asks much more than that,” said Mr Miyamoto, who’s also chief executive at structural engineering firm Miyamoto International. “It doesn’t look into damage or lost time.”
Deloitte conservatively estimated last year’s Kaikoura quake was costing the Wellington economy $1.25 million a week in productivity losses with people rehoused in different buildings.
Deloitte partner Linda Meade told the meeting there had been relatively slow progress in lifting the capital resilience to a catastrophic event, which would need more coordination between central and local governments, land owners and property developers.
Wellington City Council ordered a targeted assessment of 80 properties in the wake of the November quake, while central government separately investigated the performance of buildings that suffered major damage, including Statistics House.
The Deloitte report noted the inefficient approach to building repairs and the stretched engineering resources that delayed the assessments.
Miyamoto’s New Zealand head David Weir told the audience that the percentage code wasn’t bad, but that the capital should target more than the minimum standard.
“For Wellington, the seat of government, we need to be designing to a higher code than the minimum standard,” Mr Weir said.