Earthquake Prone Buildings

The new law came into effect on 1 July 2017 with an amendment to the Building Act 2004.

It ensures the way our buildings are managed for future earthquakes is consistent across the country, and provides more information for people using buildings, such as notices on earthquake-prone buildings and a public register.

Read more information about managing earthquake-prone buildings onMBIE's Building Performance website.

A building, or part of a building, is earthquake prone if it will have its ultimate capacity exceeded in a moderate earthquake, and if it were to collapse, would do so in a way that is likely to cause injury or death to persons in or near the building or on any other property, or damage to any other property.

Territorial authorities determine if a building or part of a building is earthquake prone using the EPB methodology, a document which sets out how territorial authorities identify potentially earthquake-prone buildings, how engineers undertake engineering assessments, and how territorial authorities determine whether a building or part is earthquake prone, and if it is, its earthquake NBS% rating.

The methodology to identify earthquake-prone buildings can be found here.

The Stratford District is within the medium seismic zone.

The following profile categories apply to the Stratford District:

The Building Code defines the significance of a building by its importance level (IL), which is related to the consequences of failure. There are five levels of importance, considered by the importance of the building to society:

Level 1: Structures presenting a low degree of hazard to life or property, such as walkways, outbuildings, fences and walls.

Level 2: Normal structures and structures not covered by other categories, such as timber-framed houses, car parking buildings or office buildings.

Level 3: Structures that may contain crowds, have contents of high value to the community or pose a risk to large numbers of people in close proximity, such as conference centres, stadiums and airport terminals.

Level 4: Buildings that must be operational immediately after an earthquake or other disastrous event, such as emergency shelters and hospital operating theatres, triage centres and other critical post-disaster infrastructure.

Level 5: Structures whose failure poses a catastrophic risk to a large area or a large number of people, such as dams, nuclear facilities or biological containment centres.

The required level of seismic performance increases with each level of importance. In general, important structures, such as hospitals, communications centres and those that provide occupation for many people, are designed for a greater level of earthquake shaking than ordinary commercial structures.

Priority buildings are certain types of buildings in high and medium seismic risk areas that are considered to present a higher risk because of their construction, type, use or location. They need to be identified and remediated within half the time allowed for other buildings in the same seismic risk areas. The Building Act s133AE also prescribes specific buildings as a priority building and they include:

• hospital buildings that are likely to be needed to provide emergency medical and ancillary services in an emergency
• buildings that are likely to be needed as an emergency shelter or an emergency centre in an emergency or that enable emergency response services to carry out their jobs in an emergency
• buildings that are used for education purposes that are regularly occupied by at least 20 people.

Other buildings or parts of buildings that could be considered priority buildings include:

• parts of unreinforced masonry (URM) buildings that could fall in an earthquake onto thoroughfares with sufficient vehicular or pedestrian traffic – including parapets, verandas, balconies and decorative ornaments attached to the façade.
• buildings that could impede transport routes of strategic importance (in terms of emergency response) if they were to collapse in an earthquake.

NBS is the new building standard (the building code). Council has to assess the performance of an existing building in an earthquake compared to a new building. This is its earthquake rating, expressed as a percentage. For example, 25%NBS means Council considers the building meets 25% of the code’s requirements for a new building. The focus is on risk to lives, rather than risk to the building. 34%NBS is considered to be the minimum level of risk and a building assessed as having an earthquake rating of less than 34%NBS is regarded as earthquake prone.

If the Council identifies your building, or part of it, as potentially earthquake prone, we will advise you of that decision. You’ll then need to contact a suitably-qualified seismic engineer and organise either an Initial Seismic Assessment (ISA) or Detailed Seismic Assessment (DSA).

You’ll have 12 months from when Council contacted you to supply this report. You can apply for one extension of 12 months, but you must do this no later than two months before the original time frame due date.

You'll need to contact Council to ascertain if your IEP meets the new criteria for EPB assesment. If the building meets the EPB criteria you can supply the Council with your IEP report. The Council will moderate this report against the EPB methodology and make a decision around suitability.

The Council will advise you of the decision and will either accept the report or you'll need to contact your engineer and organise either an ISA or DSA to meet the new EPB methodology.

An ISA is an Initial Seismic Assessment which is the first step of a Detailed Seismic Assessment and is produced by an engineer. This can be submitted to the Council as evidence of a building's NBS%.

A DSA is a Detailed Seismic Assessment and is a comprehensive seismic report supplied by an engineer. This can be submitted to Council as evidence of a building's NBS%.

The Council will assess the report and either request further information or accept the findings and document its decision.

The Council must promptly issue an EPB Notice when a building or part of a building has been identified as Earthquake Prone. The EPB Notice must be in the prescribed form, dated, identified if whole or part of building is an EPB, specify if it is a priority building and specify the NBS% and the timeframes for remediation.

Once the appropriate decisions have been made and recorded of a building or part of a building's status then the Council must also update the National Register.

If the reports confirm that the building or parts of the building are not considered earthquake prone then the building owner will be advised accordingly and this information will be stored on the property file.

Yes you can, however you can only apply for an exemption once the Council has issued the EPB Notice.

Council can prescribe a fee for this service.

Talk to our Building Services Manager by phoning 06 765 6099 or emailing stratforddc@stratford.govt.nz