Earthquake prone & dangerous buildings

This page will provide you with everything you need to know about regulations for earthquake prone and dangerous buildings.

Earthquake prone and dangerous building closures

Our website lists buildings which have been classified as either dangerous, earthquake prone or not earthquake prone. Dangerous buildings are closed by Council following engagement with the building owner and chartered professional engineers. These buildings may be closed due to a dangerous element being identified (and the building re-opened after removal of this element), or closed because of the fall hazard presented by an adjoining dangerous building.

Along with this list of dangerous buildings is a list of buildings that have been assessed as not earthquake prone.

Earthquake prone buildings policy

The Waimakariri District Council has an earthquake prone buildings policy. This is a requirement under section 131 of the Building Act. This policy affects buildings that will have its ultimate capacity exceeded in a moderate earthquake or likely to collapse causing injury or death to persons or likely to damage other property during a moderate earthquake.

If your building is deemed earthquake prone you may be required to make changes to the building so that its earthquake performance is improved as defined in the policy.

Most residential buildings are excluded from this policy as they are isolated structures and are unlikely to cause death or injury to people or damage to other property.

Read more about the earthquake prone buildings policy framework on the Department of Building and Housing website

Assessments of earthquake prone buildings

The Council has been undertaking investigations into all public and commercial buildings that could potentially be earthquake prone, as required by provisions of the Building Act 2004. Council is funding initial engineering assessments that identify both earthquake prone buildings and elements of buildings which make them dangerous, and engaging with owners to seek agreement on how best to reduce or remove the risks they pose. The assessments are being carried out to ensure public safety, both in and around the building. Once agreement is reached, the building owner has up to two years to complete a detailed engineering assessment of the building, at their own cost.  A Structural Engineer, who is also a Chartered Professional Engineer (CPEng), may at this stage be asked to provide options for strengthening, partial deconstruction or demolition of the building.

From the date of agreement (or issue of formal notice under Section 124 of the Building Act, if required), the owner has between 10 to 20 years (as specified in the Council’s Earthquake Prone Buildings Policy 2011) to reduce or remove the risks associated with their building through strengthening or demolition.  If these risks are not addressed within that time frame, the Council may order closure of the building. It is possible, however, that the outcome of the Canterbury Earthquakes Royal Commission may see applicable maximum time frames reduced.

What is an earthquake prone building?

Earthquake prone buildings are those buildings that pose a risk to those occupying them in future moderate earthquakes. A building with an assessed strength of less than 34% of a new building is unlikely to withstand a moderate earthquake.  A moderate earthquake is defined as an earthquake with one third the force of the 'design' earthquake - new buildings are designed to protect life safety in a 'design' level earthquake. 

Many of the unreinforced masonry and other earthquake prone buildings in the district have not yet been fully tested by the moderate (one third strength) earthquake - due to our distance from the recent quake epicentres.  The district has experienced a much lower level of earthquake event than was experienced in central Christchurch City.  Owners need to be aware of the risks posed by earthquake prone buildings in case a stronger earthquake occurs in future.

Stronger buildings have a much lower risk of damage in large earthquakes. At 67% strength, a building would have up to three times the risk of collapse or serious damage when compared to a new building (100% strength) in a design level quake. However a building of less than 34% strength has 10 to 20 times the risk of collapse in that same quake. The Council recommends strengthening to a minimum of 67% of the building code earthquake loads for earthquake prone buildings, to better protect the safety of building occupants.

What is a dangerous building?

Dangerous buildings have been defined by the Canterbury Earthquake Recovery Act 2011 (CER Act) as those buildings that could injure the public in a number of different scenarios, and includes all currently assessed earthquake prone buildings. For instance, the dangerous building could be earthquake-prone, but it may also pose a risk to the public in a small quake or be at risk of collapse (in whole or part) at any other time.

In addition, there could be particular elements of the building structure that pose an immediate risk to the public as assessed by a Chartered Professional Engineer.  The following are examples of specific building elements that could be deemed dangerous:

  • Cracking in masonry connecting the parapet to the facade
  • Movement or subsidence in one part of the building that weakens the whole building structure
  • A double brick chimney or heavy parapet that could fall onto a footpath.

If a building or any of its component parts are determined to be dangerous by a Chartered Professional Engineer then immediate closure, or partial closure, may be required until the danger is removed, in accordance with the Council’s Dangerous Buildings Policy.  In effect the dangerous building identification, when applied in conjunction with any immediate enforcement action, takes precedence over the longer time frames that are permitted to address earthquake prone issues.

Approach by CERA to identifying earthquake prone and dangerous buildings

CERA has largely passed the management of buildings back to the individual councils subject to the CER Act.

Waimakariri District Council has been very proactive over the last five years with over 200 Council funded engineering inspections completed. The CERA information received combined with Council's inspections, provide a very comprehensive database of the commercial buildings within our district, which has helped building owners' tenants to make decisions based on the current capacity (percentage new building standard).

There are many examples of both strengthened buildings and new builds currently being undertaken in the wider district.

Proposed changes to the manner in which earthquake prone buildings are managed

Following the Royal Commission of Inquiry hearings and recommendations, and public consultation, a new piece of legislation is currently before Parliament and awaiting its second reading.

The Building (Earthquake Prone Buildings) Amendment Bill seems likely to gain Royal assent in the first quarter of 2016, with implementation in early 2017. This Bill will replace Council's earthquake prone building policy and will ensure a national framework across all of the country.

Key changes envisaged are basing timelines for both engineering evaluations of buildings and remedial work (including strengthening and demolition) linked to the seismic hazard of the province.

For clarity, Waimakariri, Hurunui and Christchurch are all included in the high risk classification, and will have shorter time frames in which to undertake work. This is currently five years for assessment and 15 years to remediate, unless the building is of high importance and then both time frames are halved.

When the Bill becomes Law, Council will update this page for both building owners and for public information.