Setting the record straight: Percentage NBS under the Building (Earthquake-prone Buildings) Amendment Bill 2025

Percentage NBS is a comparison between the seismic performance of a building to the standard required of a new building in the same location, as determined by a structural engineer.

Under the current statutory and regulatory framework, a building is classified by a territorial authority as earthquake prone if it has a percentage NBS rating of less than 34. Earthquake prone buildings are then subject to remediation requirements within prescribed timeframes. If the Building (Earthquake-prone Buildings) Amendment Bill 2025 (the Bill) passes into legislation in its current form, percentage NBS will no longer be used by territorial authorities as the method to determine whether a building is earthquake-prone.

Key Changes

1. Earthquake-prone buildings (EPBs) will be assessed by territorial authorities in accordance with a new system, replacing percentage NBS. At a high level, the new system involves the following: 
   • the reclassification of geographic regions into low, medium, or high seismic risk.  Of particular note, Auckland, Northland and the Chatham Islands are currently anticipated to be re-classified as low seismic risk and Coastal Otago and Dunedin are re-classified as medium risk; and
   • the exemption of low-risk regions from the ne EPB regime (this means that buildings situated in low-risk regions cannot be classified as earthquake-prone and will not be subject to any statutory remediation requirements).
2. Remediation requirements for EPBs will be targeted and tiered, with taller buildings made of heavy materials or with unreinforced masonry and situated in urban centres being subject to full retrofit requirements, while smaller buildings in regional areas may be subject to façade securing or targeted retrofit requirements, only.
3. Greater flexibility in remediation timeframes, including:
   • the ability for EPB owners to apply for remediation deadline extensions of up to 15 years; and
   • the narrowing of the criteria for the assessment of “priority buildings” (which have shorter mandatory remediation timeframes)which have the effect of reducing the total number of priority buildings.

Effect of changes

The proposed new EPB system lowers the EPB threshold by focusing on buildings that pose a substantial risk to human life and, in particular, the risk of falling masonry outside the building.  The new system is expected to remove approximately 55% percent of buildings from the EPB register, with an aggregate saving of $8 billion in remediation costs. The changes will come as welcome relief for EPB owners in regional New Zealand who are currently disproportionately burdened by requirements of the existing regime.

Is % NBS gone for good?

Since the introduction of the Bill, we have noticed a perception in the market (from landlords and tenants alike) that percentage NBS is being phased out completely.  This is not correct: the proposed legislation removes NBS as the regulatory mechanism for assessing earthquake-prone buildings by a territorial authority only.

The changes do not prevent the use of percentage NBS in commercial practice (including the preparation and negotiation of seismic clauses in leases), nor render seismic clauses in current leases unenforceable. An NBS rating will still be able to be obtained by commercial parties, including within low seismic risk areas. Our expectation is that, following the passing of the Bill into law (and despite the noise), the market will continue to drive demand for seismic clauses in leases that use percentage NBS and that NBS will remain the primary factor in determining a building’s structural integrity for the purpose of seismic performance.  

Interplay with health and safety

The Health and Safety at Work Amendment Bill (HSW Bill) was introduced to the House in February 2026, and public submissions on the draft bill have closed. The HSW Bill, in its current form, clarifies that a PCBU that owns or occupies an EPB will have met its obligations under the Health and Safety at Work Act 2015 in respect of EPBs while the owner of that building meets its obligations under the Building Act 2004.  Whilst this may provide much needed certainty to PCBUs owning and occupying EPBs, it potentially widens the gap between statutory liability and actual health and safety risk, having regard to:

1. the shift in focus to safety outside the building (i.e. risk of falling masonry); and
2. the lengthening of timeframes for building owners to complete the required upgrades.

We are hopeful that, if the Bill is passed into the law, PCBUs occupying or owning EPBs will continue to frame their health and safety standards and policies in accordance with actual health and safety risk, rather than the standard for statutory compliance.

If you’d like to talk to us about what the Bill might mean for your building, lease or health and safety strategy and/or policy, we’re happy to help.

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Disclaimer: The content of this article is general in nature, does not constitute legal advice and should not be relied upon for that purpose.  Parties should seek specific legal advice tailored to their circumstances before acting on any of the matters discussed.