Evaluating a building's future seismic performance

Last updated: 1 June 2012

If you own a non-residential or multi-unit residential building in greater Christchurch, you need to understand how your building will perform in future earthquakes.

To do this, you need to get a detailed engineering evaluation (DEE) and give a copy to Canterbury Earthquake Recovery Authority (CERA). This applies to non-residential or multi-unit residential buildings in Christchurch City, Selwyn District or Waimakariri District, you need to get a detailed engineering evaluation (DEE).

Your DEE will help you make informed decisions about the continued use of your buildings. It will give you a starting point for making decisions about any repair work required and will give you information about the general state of your building.

Legally required structural upgrades

Under the Building Act you may be required to upgrade your building if it is “dangerous” or “earthquake-prone”. You are also required to upgrade buildings if the council or CERA ask you to.

In Canterbury, a building is deemed “dangerous” if:

  • there is an imminent risk to the building occupants or anyone who may be in the vicinity of the building, or
  • it is at risk of collapsing in a moderate earthquake.

An “earthquake-prone building” is a structure that is 33 per cent or less of the new building standard (NBS) for earthquake strength design.

Building owner responsibilities

You need to make your own decisions about how to manage your buildings (subject to any notices that may be given by the council or CERA). You should not wait for your council or CERA to act before dealing with any structural concerns.

If you need to do any strengthening work, you should talk to your tenants and put plans in place to carry out this work within a reasonable timeframe.

If an undamaged building is earthquake-prone it does not necessarily mean the building is unsafe and should not be occupied. Building owners need to make their own decisions about how to manage their buildings, with the benefit of expert engineering advice that takes into account the individual circumstances of each building and the risks in each case.

Five steps to help you make informed decisions about your buildings:

  1. Engage professional advice - obtain advice from a qualified chartered professional engineer (structural) with appropriate experience in seismic design and evaluation of existing buildings. You may also need to engage other professional advisors, such as lawyers, owners of neighbouring buildings and your tenants. If the property is a unit titled multi-unit residential property then the body corporate will need to be involved.
  2. Identify specific risks and vulnerabilities - the DEE should identify any structural weakness or vulnerabilities, for example from parapets and chimneys.
  3. Consider earthquake consequences - the consequences of damage to some buildings are greater, for example a hospital, school or emergency facility.
  4. Understand your options - consider the engineering/construction options for mitigating the risks.
  5. Decide what action to take - choose an option that:
  • best mitigates risk
  • is cost effective
  • provides least disruption to tenants, users, and neighbours.

This information is published by the Ministry of Business, Innovation and Employment’s Chief Executive. It is a general guide only and, if used, does not relieve any person of the obligation to consider any matter to which the information relates according to the circumstances of the particular case. Expert advice may be required in specific circumstances. Where this information relates to assisting people: