What is an NBS Rating and an Earthquake Prone Building?

May 15, 2020

When searching for a new apartment or looking to sell one you already own, knowing the NBS rating is an important piece of information to consider when assessing a property. The NBS rating reflects if a building is earthquake prone. The NBS is designed to give building occupants the ability to perform their own risk assessment when deciding to occupy or to purchase a property.

What is the NBS rating?

The NBS or New Building Standards rating is the percentage number given to a building that represents how much of the modern building standards a building meets. 

For example, if a 1970’s building only meets 20% of the new building standards, the NBS rating of the building would be 20%. 

NBS rating

What do the NBS ratings mean?

It’s important to note that the NBS rating doesn’t define the quality of a building. It means that it meets the assigned percentage of seismic performance objectives of the building code.  A building might have an NBS rating of 100% but doesn’t meet the standards for compliance of the building code. The NBS rating also does not define the building’s quality. 

What is an Earthquake Prone Building or EPB?

For a building to be considered earthquake prone, it has been deemed to meet less than 34% of NBS. 

There are two EPB categories. 0% – 20% and 21%-33%. The assigned category determines the type of EPB notice given by the local authority. 

Buildings that have an NBS of 34% or greater are not considered to be earthquake prone. 

What does it mean for a building to be earthquake prone?

An earthquake prone building is defined as is considered so “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.” You can read about the full definition here

How to look up NBS and EPB ratings?

The MBIE service ‘Register of earthquake-prone buildings’ (EPB Register) is the first place to check on a building’s NBS and EPB status. There you can search by building address, name or use the map tool to find a building. You can also find notices issued for any earthquake prone buildings attached. 

What is an Earthquake prone building notice or EPB notice?

EPB notices are designed to give the general public and users of the building a general idea of how the building might perform in an earthquake

The Earthquake prone building notice is issued by the territorial authority and will include information like the current NBS rating, timeframe in which issues with the building must be remedied within and some details of what parts of the building are prone. 

Examples of EPB notices

The following notice examples are provided by MBIE  in their Earthquake-prone buildings: notices section

Example of a notice issued to a building with 0% to less than 20% earthquake rating:

The border is orange and black striped. 

Example of a notice issued to a building with 20% to less than 34% earthquake rating

The border is white and black striped. 

Example of a notice issued to a building with an exemption:

An exemption applied when there is a low risk to safely even though the building has been classified as earthquake prone