David Kernohan: Dodgy earthquake rules another waste of money

On the Wellington waterfront there are/were large new buildings that failed in the 2016 Kaikoura earthquake. Photo / Mark Mitchell

COMMENT: In a RNZ report in May, Housing Minister Phil Twyford said dodgy meth contamination rules led to hundreds of millions of dollars being wasted, people being unnecessarily evicted and needless clean-ups ... $100 million in the case of Housing New Zealand.

What about dodgy earthquake rules? How much are we spending on strengthening so-called quake-prone buildings? As with the meth-testing fiasco, the Government is possibly placing an unnecessary or at least excessive burden on the taxpayer.

Fewer than 500 people have been killed by earthquakes in New Zealand (landslides, rock falls and building collapses) since the Marlborough earthquake of 1848. This compares with an annual road toll of about 300 people in each of the last five years (1500 people). Some 600 people commit suicide each year in New Zealand. Of the 185 lives lost in the Canterbury earthquakes of 2010 and 2011, 115 were lost in the collapse of one building. Yes, there were 15894 deaths, and 6152 injured at Fukoshima in Japan in 2011 due to earthquake and tsunami. Many buildings were lost. A nuclear reactor was damaged and continues to leak radioactive material. Damage from earthquakes in New Zealand is inevitable, but at what cost?

New Zealand is earthquake-prone (buildings are not, New Zealand is). Today, we demolish what we think is unsafe or requires expensive "strengthening", not recognising that many older buildings have already survived many quakes. We bring in rules that require our building heritage to be strengthened or demolished without any certainty that in the event of a large jolt the refurbishment or new building will be any safer.

The engineering science presents in inconsistent ways that challenge credibility. On the Wellington waterfront there are/were large new buildings that failed in the 2016 Kaikoura earthquake. And building failure is not just structural. Fixtures and fittings, service elements, construction, unrestrained parapets, balconies, decorative elements all play a role. Achieving one number, 34 per cent of the NBS, will save no one.

So, what should we do? Today, a building may be considered earthquake-prone if it is assessed to be less than one-third of the current standard for new buildings. The reality is that 34 per cent of the New Building Standard (NBS) is just a number. So is 100 per cent NBS just a number. It does not offer a 100 per cent guarantee or any guarantee.

Christchurch Cathedral is to be rebuilt to 100 per cent NBS. Why not 150 per cent NBS? What if a 400 per cent NBS quake hits? Each building needs to be considered on its merits and in its physical, topographical and geological context. We are short of expertise to do.

The current legislation may see the demise of many country towns and the older precincts of our cities as building owners choose demolition, not remediation, for simple economic reasons.

So, will we demolish the main streets of towns such as Feilding and Whanganui? The Institute of Earthquake Engineers says the risk of entering a building that is 34 per cent NBS is the same as boarding a commercial aircraft. Close the airports.

Wellington's CBD is formed on reclaimed land. Liquefaction is inevitable. Christchurch is on a swamp: Auckland on volcanoes. We live in coastal cities. A tsunami can be devastating. What is the right balance for legislation? What can we as a country afford? What is reasonable?

While the term "resilience" is much over-used it is a suitable watch-word for the way forward. We cannot prevent quakes. Even the strongest building will succumb to a direct hit.

Our future planning should not be so much about building regulation but about civil defence and preparedness. Also, we need to build more lightweight structures in steel and timber and, yes, glass. Why are we building tilt slab concrete structures, heavy concrete panel structures in Canterbury?

The conversation about where we will be by 2021 or 2025 has not been had.

• David Kernohan is a retired architect (and still worried about leaky buildings).