They’ll add anywhere between $2000 to $9000 per property to residential building work, but new rules from the Department of Building and Housing will make for stronger building foundations in Canterbury. Changes to the Building Code were recently announced by Canterbury Earthquake Recovery Minister Gerry Brownlee.
As part of those changes, the Department of Building and Housing has decided to increase the seismic hazard factor for the design of all buildings by 35 per cent from 0.22 to 0.3, based on the best scientific and structural engineering advice available. Concrete flooring for houses will also need to be tied and reinforced.
The fluctuation of costs in implementing these rules will depend on the size of the house, the foundation option chosen and the state of the ground.
"Residential homes built in Christchurch will be required to have increased bracing and foundations and be more resistant to bowing or cracking," says Brownlee.
“These changes will mean new buildings are constructed better to withstand any future severe earthquakes.”
The changes began taking place last week in the three local authority areas in greater Christchurch: Christchurch City, Waimakariri, and Selwyn District Councils. The seismic hazard factor for buildings in much of the Selwyn District, closer to the Alpine Fault, is already greater than 0.3.
Building and Construction Minister Maurice Williamson says the changes are based on the best available science and the advice of recognised seismic and structural engineering experts.
The Department of Building and Housing also worked closely with the Christchurch City Council in developing the new seismic hazard factor.
"Ground shaking in Christchurch on 22 February was very violent and exceeded Building Code design requirements for buildings in the area," says Williamson.
"The scientific assessment of the earthquakes and how buildings performed in them does not support an increase in the seismic hazard factor above the 0.3 level.”