Policies

You are here > Home > Council Documents > Policies > Earthquake-Prone Building Policy

Earthquake-Prone Building Policy

Reference:  P11-006 
Status: Approved by the Council on 20 December 2011

POLICY PURPOSE

1. To clarify how the Council will identify, assess and reduce or remove the danger posed by earthquake-prone buildings in New Plymouth District.

POLICY OBJECTIVE

2. The objective of this policy is to remove the earthquake-prone status of buildings to reduce the potential for injury to the public, loss of life, or damage to other property in a moderate earthquake.

LEGISLATIVE REQUIREMENTS

3. Section 131 and 132 of the Building Act 2004 requires Council’s to adopt and then review a policy on earthquake-prone buildings.

4. The policy is required to cover:

• The approach that the Council will take in performing its functions under the Building Act 2004.
• The Council’s priorities in performing those functions.
• How the policy will apply to heritage buildings.

SEISMICITY OF THE DISTRICT

5. New Plymouth district is in a zone of low seismic activity. There are three known active fault lines within the district capable of producing significant earthquakes. These are the Inglewood and Norfolk faults which lie on either side of the Inglewood township and extend from southwest to northeast and the Turi fault which lies to the west of New Plymouth out to sea. Of the fault lines within the district the Turi fault is the most likely to affect the buildings in the North Taranaki region. A major earthquake outside of the region is the most likely event to produce sufficient ground movement to adversely affect the regions buildings, though the probability of a major earthquake affecting the New Plymouth district is low.

6. The buildings within the New Plymouth district comprise a range of types and ages reflecting steady development over the last 100 years from unreinforced masonry buildings to some modern multi-story steel and concrete buildings, the latter being particularly evident in New Plymouth central business district and urban area as opposed to the outlying townships. The refurbishment and redevelopment of some buildings within New Plymouth for new uses has also seen some of the unreinforced masonry and brick buildings undergo strengthening. These buildings are likely to not be earthquake-prone, an assessment of their structural design and strengthening would confirm this.

POLICY PRINCIPLES 

7. Through this policy the Council seeks to ensure that:

• There is a reduced risk to people who use buildings or are in the vicinity of buildings during an earthquake.
• The social and economic implications of requiring the reduction or removal of the danger of earthquake-prone buildings are considered in an integrated manner.
• Timeframes to reduce or remove the danger posed by an earthquake-prone building are commensurate with the risk of the building.
• Heritage values of earthquake-prone buildings are preserved where possible.  
• People can access information on earthquake-prone buildings.

OVERALL ASSESSMENT APPROACH

8.  The Council’s earthquake-prone building policy under the Building Act 2004 takes a proactive approach that reflects the Council’s determination to reduce earthquake risk over time in a way that is acceptable in social and economic terms to its ratepayers.

9. Through the policy the Council:

• Will review the district’s building stock to identify buildings that could be earthquake-prone under the definition in the Building Act 2004.
• Will assess broadly the performance of those buildings in relation to the Standard for new buildings and in particular, to the standard defined for earthquake-prone buildings.
• Will determine and compile from this broad assessment a list of buildings that are likely to be earthquake-prone in terms of the Building Act 2004.
• Will advise owners of these buildings of the results of the Council’s broad assessment and invite them to meet with and/or obtain further details from the Council on future requirements.
• Will, within a 6 month or longer time-frame as determined by the risk posed by the building, require owners of buildings that are likely to be earthquake-prone to obtain a more detailed structural assessment of the building to confirm the buildings status and propose any strengthening requirements.
• Will work with building owners to seek an agreement to address the danger of the earthquake-prone building.  
• May exercise its powers under section 124 of the Building Act 2004 to address the danger of an earthquake-prone building.   

ASSESSMENT CRITERIA FOR EARTHQUAKE-PRONE BUILDINGS

10. The definition of an earthquake-prone building is set out in section 122 of the Building Act 2004 and in the related regulations that define a moderate earthquake. These definitions are included in Appendix 1 of this policy.

11. Buildings will need to be assessed to determine if they are earthquake-prone. For practical purposes, the Council will define earthquake-prone buildings as those that, when subject to moderate earthquake shaking, do not meet or exceed the criteria for ultimate limit state as defined in the loadings and materials Standards for new buildings.

12. The Council will use the New Zealand Society of Earthquake Engineers (NZSEE) Recommendations as its preferred basis for assessing buildings. These Recommendations are designed to be used in conjunction with AS/NZS 1170 Structural Design Actions, NZS 3101 Concrete Structures Standard, NZS 3404 Steel Structures Standard and other materials Standards. The NZSEE Recommendations are reflected in this policy where appropriate.  

STRENGTHENING REQUIREMENTS

13. To ensure existing buildings are not earthquake-prone the minimum required strength is 34% of the new building Standard. The Council will require all buildings to be strengthened to at least this level.

14. The Council encourages buildings to be strengthened to a higher level of 67% of the new building Standard. This higher level is in line with NZSEE recommendations which consider this higher level appropriate to reduce or remove the earthquake-prone and earthquake-risk danger to buildings. This is particularly important to those buildings that have a post disaster function, whose failure poses catastrophic risk to a large area or a large number of people, or buildings that contain large numbers of people.

15. There are several benefits for strengthening buildings to a higher level, these include:

• Improved levels of safety for building users, surrounding buildings and people using the neighbouring area.
• Improved resilience against the damaging effects of an earthquake.
• Less risk of impact on business continuance.
• Improved insurance leverage.
• May decrease the degree of seismic upgrading required for a subsequent ‘change of use’ to the building. 
• Improved ability to meet stricter strengthening requirements from possible future legislative changes such as those that could result from the Royal Commission into the Christchurch earthquakes.    

PRIORITIES FOR IDENTIFYING AND ASSESSING EARTHQUAKE-PRONE BUILDINGS

16. The Council will prioritise the identification and assessment process for earthquake-prone buildings primarily using the importance level of buildings as defined in the Australia/New Zealand Standard 1170.0: 2002. These are included in Appendix 2 of this policy.

17. Category A heritage buildings are also a priority in the identification and assessment of earthquake-prone buildings.

18. Building elements such as, but not limited to; facades, verandas, parapets and stone/brick chimneys will be included in all assessments where appropriate. Requirements to reduce or remove the danger posed by these building elements will be of high priority when considering proposed building work plans.      

19. The staged completion of work to reduce or remove the danger may be accommodated by the Council where risk allows and staging is practical. In determining risk the Council will consider the importance level of the building, the assessment of its structural performance and the level of risk on adjoining buildings and the neighbouring area with particular reference to the intensity of public use. Where work is staged, it will be prioritised on a risk basis. The resultant work plan will state completion dates for each stage of the work. The objective will be that all the work is completed within the maximum indicative timeframes stated in the priority categories in section 20 of this policy. The timeframes commence on the date of formal agreement between the Council and the owner or on the date of issue of formal notice.

20. The priority categories for identifying and assessing buildings are as follows:
• Category 1 (15 years maximum indicative timeframe for completion of building works)
o Importance Level 5- special buildings, for example buildings that have special functions or whose failure poses catastrophic risk to a large area or a large number of people as defined in AS/NZS 1170.0: 2002 (Appendix 2).  
o Importance Level 4- buildings with special post-disaster functions for example medical emergency or surgical facilities  as defined in AS/NZS 1170.0: 2002 (Appendix 2).

• Category 2 (20 years maximum indicative timeframe for completion of building works)
o Importance Level 3- buildings that as a whole may contain people in crowds or contents of high value to the community or pose risks to people in crowds as defined in AS/NZS 1170.0: 2002 (Appendix 2).
o Importance Level 2- normal buildings not in other importance levels as defined in AS/NZS 1170.0: 2002 (Appendix 2).

• Category 3 (30 years maximum indicative timeframe for completion of building works)
o Heritage buildings with a heritage classification of Category A under the New Plymouth District Plan that have not already been earthquake strengthened to withstand a moderate earthquake.

21. Buildings that fall into more than one of the above categories will be prioritised under the higher importance category.  

IDENTIFYING AND ASSESSING EARTHQUAKE-PRONE BUILDINGS

22. The Council will undertake the following process to identify and assess earthquake-prone buildings:

Step 1: Initial identification- an initial desktop review to identify buildings in the district that could be earthquake-prone in relation to the Building Act 2004. Council buildings will be included in this initial desktop review. This step may include a brief inspection of each building where required.

Step 2: Initial evaluation process of potentially at risk buildings- Assess the performance of the potentially at risk building stock by using the NZSEE Initial Evaluation Process (IEP). Inspections will be carried out where necessary. This will be done by a suitably qualified engineer and at the Council’s cost. The outcome of this assessment will be a list of buildings that are likely to be earthquake-prone. The Council will keep a register of this information.

Step 3: Advising owners of the IEP outcome- owners will be advised in writing of the outcome of the IEP. Owners are invited to discuss the outcome with the Council.

Step 4:  Requiring a more detailed structural assessment- in order to confirm the status of a building that is likely to be earthquake-prone and to identify any strengthening requirements, the Council will require the owners, within a 6 month or longer timeframe as determined by the risk posed by the building, to obtain a more detailed structural assessment of the building at the owner’s expense. The assessment is to be done by a suitably qualified engineer. 

 It is recommended that this structural assessment also covers the option of strengthening to 67% of the new building Standard.  The benefits of the greater level of strengthening are identified in section 15 of this policy.

Step 5: Review of structural assessment and confirmation of building status- the Council will review the structural assessment to determine the earthquake-prone status of the building. The Council will use suitably qualified engineers to review the information supplied by the owner. The review may involve liaison with the owner and the owner’s engineer. Where the Council is satisfied that the building is not earthquake-prone, the recorded status of the building will be changed and the owner will be advised of the Council’s decision.            

Step 6: Requiring reduction or removal of the danger- before exercising its powers under section 124, once a building is confirmed to be earthquake-prone the Council will work with owners to develop, within a timeframe of 6 months, an acceptable approach for dealing with the danger of the earthquake-prone building. The approach may include a work plan (which may be staged) prepared by the owner and will be subject to monitoring and enforcement requirements by the Council ensuring that timeframes and milestones are met.

Options to reduce or remove the danger include one or more of the following types of building work:

• Reduce the danger by strengthening the building or part of the building so that it is no longer earthquake-prone;
• A combination of removing some of the offending part(s) of the building and strengthening the remainder of the building so that it is no longer earthquake-prone;
• Remove the danger by removing the offending part(s) of the building so that it is no longer earthquake-prone; or
• Remove the danger by demolishing the building.   

Step 7: Exercising powers under section 124- the Council may exercise its powers under section 124 of the Building Act 2004 if:

• No acceptable approach is reached to reduce or remove the danger of the building.
• The owner fails to respond to any Council correspondence.
• The owner fails to comply with any requirement or required timeframe detailed in this policy or in any Council correspondence to the owner.

Powers under section 124 of the Building Act enable the Council to:

• Put up a hoarding or fence to prevent people from approaching the building nearer than is safe.
• Attach a notice to the building that warns people not to approach the building.
• Give written notice requiring work to be carried out on the building.

Step 8: Owners right of appeal- under section 177 of the Building Act 2004 owners have a right of appeal against the classification of their building as earthquake-prone. Should an owner dispute the classification they may apply for a determination to the Chief Executive of the Department of Building and Housing.  

HERITAGE BUILDINGS  

23. It is important that heritage buildings are able to survive a moderate earthquake so that their historical values are retained for future generations. While heritage buildings will be assessed in the same way as other potentially earthquake-prone buildings, specific consideration will be given to the importance of retaining the recognised heritage features where earthquake strengthening is to take place. To achieve this, the Council will encourage the use of sympathetic, less invasive upgrading methods and recommend building owners seek advice from the New Zealand Historic Places Trust and other recognised heritage experts.

24. Where viable upgrading options compromise heritage values, the Council may, where appropriate in terms of the risk to building users and the public, agree, by way of a Council resolution, to a reduced level of strengthening by way of a formal waiver under the provisions of the Act. Alternatively a determination may be applied for through the Department of Building & Housing.

25. Applications may be made to the Council’s Heritage Protection Fund to assist with the seismic upgrading of recognised heritage buildings in the New Plymouth district. The adequacy of this fund to meet demand will be monitored. If there is a need for increased funding, this will be identified for consideration when budgets are reviewed.

INTERACTION BETWEEN THE POLICY AND OTHER RELATED SECTIONS OF THE BUILDING ACT 2004

26. Section 112 Alterations to existing buildings- whenever a building consent application is received for significant upgrading or alteration (that represents 30% or more of the improved value of a building over any five year period) of a building that is or could be earthquake-prone, the Council will require a detailed structural assessment of the building in terms of its earthquake-prone status at the owners expense.

If the building is shown to be earthquake-prone, then the Council will require that the building owner reduces or removes the earthquake-prone danger posed by the building consistent with the requirements of this policy.
 
27. Section 115 Change of use- whenever a building consent application is received for change of use of a building that is or could be earthquake-prone, then, irrespective of the general priorities set by the Council for dealing with earthquake-prone buildings, it will be a requirement of the building consent that the owner make a detailed assessment of the earthquake performance of the building to determine whether or not it is an earthquake-prone building in its existing condition.

If the building is shown to be earthquake-prone then the Council will require that the building be strengthened to comply as nearly as is reasonably practicable with every provision of the Building Code that relates to structural performance as is required by section 115(b)(i)(a). (In this instance the requirement for earthquake-prone buildings would be the same as that for non-earthquake-prone buildings).

ECONOMIC IMPACT OF THE POLICY

28. The true economic impact of this policy will not be known until after the identification and assessment phases of the process have been completed and the extent of the required strengthening and/or demolition work has been identified. An economic impact assessment of this policy will be undertaken at this time.  

AVAILABILITY OF INFORMATION ON EARTHQUAKE-PRONE BUILDINGS

 
29. The Council will keep a register of all earthquake-prone buildings. This will include those likely to be earthquake-prone, those confirmed to be earthquake-prone and those assessed and found not to be earthquake prone. The register will also note completed and/or outstanding work to reduce or remove the danger posed by the building. The information on this register will be publicly available for inspection at Council offices on request and on the Council website. In addition, the following information will be placed on the Land Information Memoranda (LIM) and Project Information Memoranda (PIM) for each earthquake-prone building:

• The address and legal description of the land and building.
• A statement that the building is on the Council’s register of earthquake-prone buildings.
• The date by which strengthening or demolition is required (if known) and the work known to be completed. Most upgrading will be subject to building consent and noted accordingly.
• A statement that further details are available from the Council.

In granting access to information concerning earthquake-prone buildings, the Council will conform to the requirements of any relevant legislation. 

POLICY CONTACT

30. The policy holder is the Customer and Regulatory Services Team within the Community Services Group.

POLICY REVIEW 

31. Section 132 of the Building Act 2004 requires that a Council must complete a review of the policy within five years after the policy is adopted and then at intervals of not more than five years. Next review is to be completed by 2016.

Reviewed five yearly (new review 2016).

APPENDIX 1

32. Section 122 of the Building Act 2004 defines the meaning of an earthquake-prone building:

(1) A building is earthquake-prone for the purposes of this Act if, having regard to its condition and to the ground on which it is built, and because of its construction, the building-
(a) will have its ultimate capacity exceeded in a moderate earthquake (as defined in the regulations): and
(b) would be likely to collapse causing-
(i) injury or death to persons in the building or to persons on any other property; or
(ii) damage to any other property.

(2) Subsection (1) does not apply to a building that is wholly or mainly used for residential purposes unless the building-
(a) Comprises 2 or more storeys; and
(b) Contains 3 or more household units

The Building Regulations 2005 defines a moderate earthquake (reference above in (1) (a)) as:

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.

 

APPENDIX 2

33. Importance levels of buildings from Australia/New Zealand Standard 1170.0: 2002.

Importance Level	Comment	Examples
1	Structures presenting a low degree  of hazard to life and other property	Structures with a total floor area <30m2 Farm buildings, isolated structures, towers in rural situations Fences, masts, walls, in-ground swimming pools
2	Normal structures and structures not in other importance levels	Buildings not included in Importance Levels 1, 3,4 Single family dwellings Car parking buildings
3	Structures that as a whole may contain people in crowds or contents of high value to the community or pose risks to people in crowds	Buildings and facilities as follows: a) Where more than 300 people can congregate in one area b) Day care facilities with a capacity of greater than 150 c) Primary school or secondary school facilities with a capacity greater than 500 d) College or adult education facilities with a greater capacity than 500 e) Health care facilities with a capacity of 50 or more resident patients but not having surgery or emergency treatment facilities f) Airport terminals, principal railway stations with a capacity greater than 250 g) Correctional institutions h) Multi-occupancy residential, commercial (including shops), industrial, office and retailing buildings designed to accommodate more than 5000 people and with a gross area greater than 10000m2 i) Public assembly buildings, theatres and cinemas of greater than 1000m2 Emergency medical and other emergency facilities not designated as post disaster Power-generating facilities, water treatment and wastewater treatment facilities and other public utilities not designated as post-disaster Buildings and facilities not designated as post-disaster containing hazardous materials capable of causing hazardous materials capable of causing hazardous conditions that do not extend beyond the property boundaries
4	Structures with special post-disaster functions	Buildings and facilities designated as essential facilities Buildings and facilities with special pose-disaster function Medical emergency or surgical facilities Emergency service facilities such as fire, police stations and emergency vehicle garages Utilities or emergency supplies or installations required as back up for buildings and facilities of Importance Level 4 Designated emergency shelters, designated emergency centres and ancillary facilities Buildings and facilities containing hazardous materials capable of causing hazardous conditions that extend beyond the property boundaries
5	Special structures (outside the scope of this Standard-acceptable probability of failure to be determined by special study)	Structures that have special functions or whose failure poses catastrophic risk to a large area (e.g. 100km2) or a large number of people (e.g. 100,000) Major dams, extreme hazard facilities