Every building in New Zealand, except single-storey homes, will be assessed for earthquake risk and the results made public under Government proposals released this morning.
Any building found to be at risk of collapse will have to be strengthened or demolished within 15 years under the proposed changes, which form the Government's response to a Royal Commission investigation into earthquake-prone buildings after the Canterbury quakes.
The Government planned to adopt many of the commission's recommendations, but has chosen longer timeframes and lower minimum standards of building strengthening than the report proposed.
Unreinforced masonry buildings resulted in the death of 39 people in the February 22, 2011 earthquake in Christchurch.
The commission found there was poor information on earthquake-prone buildings in New Zealand, lack of central guidance on defining and repairing these structures, and variable council approaches to fixing the problem.
Only 23 of 66 local authorities were able to tell the commission how many earthquake-prone buildings were in their area.
Under the Government proposals, around 193,000 non-residential or multi-unit, multi-storey residential buildings will have to be assessed for earthquake risk within five years.
There was an estimated 15,000 to 25,000 buildings which were at risk of collapse in a moderate-sized tremor.
Building and Construction Minister Maurice Williamson said the recommendations in the report could have significant economic consequences for the building owners.
But he stressed that the Government's proposals, which were released in a consultation paper, would strike a balance between increasing safety and managing the economic pressures of strengthening and removing vulnerable buildings.
He also emphasized that property owners who upgraded their buildings would benefit from a higher property value, higher rent, and lower insurance premiums.
The Government's proposals were broadly in line with the Royal Commissions' recommendations, but did not go as far as the commission in some areas.
Mr Williamson said making the timeframes too short or ramping up the minimum earthquake-proofing standards would lead to "catastrophic" increases in costs to property owners.
The Government's consultation document emphasised that the risk of life-threatening earthquakes remained very low in New Zealand and that there was no such thing as a completely earthquake-proof building.
The commission recommended that earthquake-prone buildings should be strengthened to 50 per cent of the building code - up from the current threshold of 33 per cent.
Government proposed leaving it at 33 per cent. Mr Williamson said increasing the threshold to just 34 per cent would cost $700 million more over 15 years.
The commission wanted councils to be able to demand strengthening of vulnerable residential buildings, but Mr Williamson said this was not necessary because so few people were harmed in their homes in the Christchurch quakes.
The Royal Commission also wanted faster timeframes for identifying and repairing unreinforced masonry buildings.
The report was the fourth volume of seven to be released by the commission on the quakes.
The next volume, which focussed on the collapse of the CTV building, will be released on Monday.