This page will provide you with everything you need to know about earthquake prone and dangerous buildings in the district. For further information please contact Les Pester, Environmental Services Manager.
Earthquake Prone and Dangerous Buildings and Closures
The Council has provided a list of buildings in the Waimakariri District that
are earthquake prone or dangerous, closed by the building owner pending
further engineering assessment, or partially closed because of a
dangerous building nearby. The list now also includes buildings that have been assessed and are 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
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.
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.
Council’s Assessments of Earthquake-prone Buildings
The Council is currently 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.
So far approximately 30 buildings in the district have been identified as 'earthquake prone', as they are less than 33 per cent of the new building standards as required by the Building Code.
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.
Why Plaque Earthquake Prone Buildings?
A plaque will clearly show that a building has been identified as earthquake prone. The Council believes that the public, including building tenants and their staff, should be fully informed, in making a decision to enter, or not enter, any particular building that is assessed as earthquake prone.
The Council has, in the last few months, developed an initial list of earthquake prone buildings. This is information that it believes should be available to the public. If building owners do not wish to display the plaque identifying their building as earthquake prone, the Council will instead issue a notice under the Building Act Section 124 to be placed at the entrance to the building.
Further explanation is available from the Council’s Earthquake Prone Buildings Policy 2011 (please see link at bottom of page).
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 Canterbury Earthquake Recovery Authority (CERA) to Identifying Earthquake Prone and Dangerous Buildings
CERA intends to write to the owners of all commercial buildings in Greater Christchurch including the Waimakariri District to request a Detailed Engineering Evaluation (DEE) for each building. This assessment would provide further certainty to the public and the Council about the structural integrity of commercial buildings. CERA is able to close or restrict access to any building until the DEE is provided, and if it considers any building to be dangerous it may also order demolition or partial demolition (in accordance with the CER Act, sections 4, 38 and 40). More information about the CERA assessment requirements is available on the CERA website.
Council staff are now working with CERA officers to ensure that the CERA approach to commercial building owners is complementary and aligned with the approach the Council has taken. It should ensure there is less duplication and that the public is best protected by prioritised assessments of the most at risk buildings. We will also look to work with building owners and businesses to minimise the impact on their business activities.
Please contact Greig Wilson on (03) 311 8900 if you have queries or concerns about any of the above requirements.
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