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Earthquake prone buildings

Earthquake prone buildings are managed under the Building Act and are divided into three seismic risk areas and each risk area has set time frames for identifying and taking action to strengthen or remove earthquake-prone buildings. 

What does earthquake prone buildings (EPB) mean? 

A building is earthquake prone if a building or a part of building can collapse on a person or onto other properties and cause injury or death to a person or damage to other buildings. 

Council identifies earthquake prone buildings by using the Earthquake Prone Building methodology which outlines how territorial authorities should identify earthquake prone buildings, how engineers undertake assessments, and sets out the timeframes for remedial action. 

An earthquake prone assessment is undertaken by an engineer that assigns an earthquake rating to a building. 

This earthquake rating means a buildings seismic resistance capacity in the event of an earthquake and is calculated in comparison to a new build standard (NBS). A building with a rating of less than 34% NBS is deemed to be earthquake prone and those with a rating of more than 67% NBS are deemed to be unlikely to be a risk in the event of an earthquake. 

View the New Zealand Seismic Risk area map for more information.

What does percentile NBS or NBS rating mean? 

The Initial NBS, or New Building Standard rating, is a high-level assessment of the seismic risk of a building, compared to a building built to the current building code. This assessment does not predict if a building would survive in an earthquake but is rather a representation of the vulnerability of a building in the event of an earthquake.  

Key information

Dive a bit deeper into the topic with our key information below to make your building earthquake safe.

There is a clear defined process how you get to your EPB.

  1. Council identify possible EPB. 
  2. Letter to the owner of the building requiring that an EQP assessment report be submitted to Council. 
  3. The owner contract structural engineer to undertake an assessment. 
  4. EQP assessment report supplied to Council. If less than 34%NBS classified as EPB. 
  5. Letter issued to owner with time frame for earthquake strengthening to be done. 
  6. Added to the Ministry of Business, Innovation & Employment EPB register. 
  7. Earthquake strengthening works completed. 
  8. Remove for MBIE EPB register. 

There are three categories for earthquake prone buildings. 

Category High seismic risk areas and medium seismic risk areas
Category A Unreinforced masonry buildings
Category B Pre-1976 buildings that are either three or more storeys or 12m or greater in height above the lowest ground level (other than unreinforced masonry buildings in Category A)
Category C Category C Pre-1935 buildings that are one or two storeys (other than unreinforced masonry buildings in Category A)


The time frames are: 

In a high risk seismic zone, territorial authorities (city or district councils) must identify potentially earthquake-prone buildings by: 

  • Priority buildings - 1 July 2022 
  • Other buildings - 1 July 2027 

In a high risk seismic zone, owners of earthquake-prone buildings must carry out seismic work within (time frames are from issue of an EPB notice): 

  • Priority buildings - 7.5 years
  • Other buildings - 15 years