New Building Standard (NBS)
A percentage rating that expresses an existing building's earthquake strength relative to the minimum standard required for a new building — 100% NBS means the building meets the current code for a new build.
What is a New Building Standard (NBS)?
The New Building Standard (NBS) percentage is the key metric used in New Zealand to express a building's seismic capacity. It compares an existing building's earthquake resistance to what would be required if it were built new today under the current Building Code.
A building rated at 100% NBS meets the minimum seismic standard for a new building. A building at 67% NBS has two-thirds of the strength of a new building. Below 34% NBS, a building is legally classified as earthquake-prone. The higher the NBS percentage, the more earthquake-resistant the building.
NBS ratings are determined through a seismic assessment carried out by a structural engineer. There are different levels of assessment — an Initial Seismic Assessment (ISA) provides a broad estimate, while a Detailed Seismic Assessment (DSA) gives a more precise rating. The NBS rating considers the building's weakest element — a building is only as strong as its most vulnerable structural component.
Why It Matters for Due Diligence
The NBS rating directly affects safety, insurance, lending, and property value. Buildings below 34% NBS face mandatory strengthening. Even buildings between 34% and 67% NBS (sometimes called 'earthquake risk') may attract higher insurance premiums and lower lending ratios.
When buying in a multi-storey or older building, ask for the NBS rating and the engineer's report. Understand whether the rating is from an ISA (rough estimate) or DSA (detailed assessment). If no assessment has been done, this is itself a concern — consider making your purchase conditional on a satisfactory seismic assessment.
How to Check
Ask the building owner, body corporate, or real estate agent for the building's seismic assessment report and NBS rating. Check the MBIE Earthquake-Prone Buildings Register for any EPB notices. The council building file may contain seismic assessment reports. For buildings without an assessment, you can commission one from a structural engineer — an Initial Seismic Assessment typically costs $2,000-$10,000 depending on building size.
Frequently Asked Questions
What is a good NBS rating?
Above 67% NBS is generally considered acceptable and means the building has more than two-thirds of the seismic capacity of a new building. Above 100% NBS means it exceeds the current standard. Between 34% and 67% is legal but represents a higher risk. Below 34% is earthquake-prone and will require strengthening.
Does a high NBS rating mean the building is earthquake-proof?
No building is earthquake-proof. The NBS rating expresses relative strength compared to the minimum code for a new building. Even a 100% NBS building could sustain damage in a major earthquake — the code aims to protect life safety, not prevent all damage. Higher NBS means greater resilience, but earthquakes can always surprise.
Related Terms
Earthquake-Prone Building
GlossaryA building assessed as having structural performance below 34% of the New Building Standard (NBS) for earthquake resistance, making it legally earthquake-prone under the Building Act 2004.
Building Code
GlossaryThe New Zealand Building Code — a set of minimum performance standards that all building work must meet, covering structure, fire safety, moisture, energy efficiency, and accessibility.
Body Corporate
GlossaryThe legal entity made up of all unit title owners in a multi-unit development, responsible for managing common property and shared affairs.
Liquefaction
GlossaryA phenomenon where saturated, loose soil loses its strength during an earthquake and behaves like a liquid, causing the ground to shift, sink, or eject sand and water.
Fault Line
GlossaryA geological fracture in the earth's crust where two tectonic plates or rock masses meet, and where earthquakes are most likely to occur.
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