Earthquake-prone Buildings
The Building Act 2004 requires all Councils to assess public buildings and some large residential buildings (such as multi-unit residential apartments) for earthquake resistance.
Hawke’s Bay is well known for its regular earthquakes and Hastings District Council is making this assessment a priority. To reduce the burden on building owners, Council has decided to pay for the initial structural engineering assessment which needs to be carried out.
Why is this process necessary?
Hastings District Council’s ‘Dangerous, Earthquake Prone and Insanitary Buildings Policy 2006’ (the Policy) was adopted in May 2006 as a requirement under the Building Act 2004. This policy was publicly notified and submissions were received and considered by Council at the time. The Policy is due for review in 2011.
The Policy applies to buildings within the Hastings district to which the public has access, or to residential buildings of two or more floors and containing three or more household units. The Policy relies on the New Zealand Society of Earthquake Engineers (NZSEE) guidelines as the basis of how to evaluate potentially earthquake prone buildings.
The Building Act and regulations set out that buildings that will not withstand a moderate earthquake (buildings that are less than one third or 33% of current design strength) are earthquake prone.
What happens if my building is identified as potentially earthquake prone?
Council has engaged Strata Group Consulting Engineers Ltd, a local structural engineering company, to carry out the initial evaluations in accordance with the New Zealand Society of Earthquake Engineers guidelines. The cost of these initial evaluations will be paid by Council.
The evaluations will be carried out over a six month period and will require an onsite evaluation of buildings identified as being potentially earthquake prone.
Will there be any damage to my building?
The assessment will involve mainly visual, non-invasive inspections, however on some buildings there may be the need for some invasive testing to be carried out (e.g.: core drilling of columns etc.). It is the intention of Council to avoid invasive testing where possible and, when required, will keep this type of testing to a minimum.
Who pays for repairs after testing?
Unfortunately Council’s Policy states that the owner of the buildings will be responsible for the repair of any damage incurred during the invasive testing.
Will I get a copy of the report and can I challenge the results?
A copy of the report will be provided to all building owners. Owners may wish to have the report reviewed by their own earthquake engineering specialist or may accept the reports findings without further review.
What will I have to do?
- If your building has been identified as not being earthquake prone, there is no requirement to do anything.
- If your building has been identified as being earthquake prone, you need to upgrade your building to a minimum of one third or 33% of current design strength.
Who pays to upgrade a building?
It is the owner’s responsibility to pay for all costs associated with upgrading their buildings. Building consents will be required for any upgrade work on buildings.
How long do I have to upgrade my building?
Council will discuss with you the expected length of time that would be acceptable to both you and Council. It is accepted that this particular design engineering work takes time and that the design is acceptable to you as the owner and the tenants or occupiers of the building.
How can I future proof my building?
As stated in the article ‘Earthquake prone buildings (PDF 240kB)’, there is no requirement in the current legislation to strengthen earthquake prone buildings to any particular level other than achieving a minimum strength one third of the current requirements.
However, Council believe it may prudent in many situations for owners to strengthen to higher levels. If an owner upgrades to the 33% threshold only, further strengthening may be required at a later date should the requirements be amended to higher standards.
On release of the evaluation report, you may feel it desirable to have your own engineer review and provide comment and advice on the findings in that regard.
Further questions
If you have any further questions, please contact Michael Skelton, Team Leader Building Compliance:
michaels@hdc.govt.nz or phone 06 871 5000 ext 5358.
Please Note:
Definitions:
Earthquake Prone Building (Section 122, Building Act 2004)
Moderate Earthquake (Section 7, Building Regulations 2005)
Meaning of Earthquake Prone Building:
- A building is earthquake prone for the purposes of the Building Act if, having regard to its condition and to the ground on which it is built, and because of its construction, the building –
- will have its ultimate capacity exceeded in a moderate earthquake (as defined in the regulations); and
- would be likely to collapse causing –
- injury or death to persons in the building or to persons on any other property, or
- damage to any other property.
- Subsection (1) does not apply to a building that is used wholly or mainly for residential purposes unless the building –
- comprises two or more storeys; and
- contains three or more household units.
Earthquake Prone Buildings: moderate earthquake defined
For the purposes of Section 122 (meaning of earthquake prone building) of the Building Act, moderate earthquake means, in relation to a building, an earthquake that would generate shaking at the site of the building that is of the same duration as, but that is one third as strong as, the earthquake shaking (determined by normal measures of acceleration, velocity and displacement) that would be used to design a new building at the site.
