Earthquake Strengthening: Costs and Requirements for NZ Homeowners

The Canterbury and Kaikoura earthquakes brought seismic risk into sharp focus for New Zealanders. What followed was a comprehensive overhaul of earthquake-prone building legislation, creating obligations that affect property owners across the country. If you own, or are considering buying, an older property, understanding these requirements is no longer optional.

This guide explains what earthquake-prone designation means, who it applies to, what strengthening involves, and what it might cost.

Understanding Earthquake-Prone Building Classification

Under the Building Act system, a building or part is earthquake-prone when its ultimate capacity in a moderate earthquake would be exceeded and collapse would be likely to cause injury, death or damage to other property. A determination generally corresponds to less than 34% NBS, but %NBS does not predict performance in a particular earthquake.

• Less than 34% NBS: may meet the statutory earthquake-prone threshold when the Building Act collapse-consequence test is also met
• 34% NBS or above: not earthquake-prone under this statutory threshold, but other seismic risks and provider requirements may still need building-specific assessment
• %NBS is a relative engineering measure, not a prediction of how a building will perform in a particular earthquake
• Assessment scope, vulnerabilities and engineering advice matter alongside any headline %NBS figure

Territorial authorities identify potentially earthquake-prone buildings and issue EPB notices after the statutory assessment process. Priority-building status applies only to specified categories in high or medium seismic areas; check the notice and register rather than inferring priority status from region alone.

Does This Apply to Your Home?

Many buildings used wholly or mainly for residential purposes are outside the EPB system, subject to the Building Act’s scope rules. Mixed-use, multi-unit and other buildings require a building-specific check with the council and EPB Register.

However, the exemption does not apply in several important situations:

• Some multi-unit residential buildings, depending on height, size, use and the statutory scope rules
• Mixed-use buildings with residential and commercial components
• Buildings that have been used, or could potentially be used, for purposes other than residential
• Buildings in high or medium seismic areas that meet a specified priority-building category

For a unit title, review the body corporate’s engineering reports, meeting resolutions, levy allocation, funding plan and relevant interests. The exact approval and cost allocation depend on the Unit Titles Act, body corporate decisions and property documents.

What Buildings Are Most at Risk?

Certain building types are more likely to be earthquake-prone due to their construction methods:

• Unreinforced masonry (URM): Brick buildings built before the 1930s without steel reinforcement
• Pre-1976 concrete: Buildings designed before modern seismic codes were introduced
• Buildings with soft storeys: Ground floors with large openings, like garages or retail fronts
• Buildings with irregular shapes: L-shaped or multi-level structures that twist in earthquakes
• Buildings on poor ground: Properties on liquefiable or unstable soils

For an apartment or unit, review the EPB Register, council file, body corporate disclosures, existing seismic assessments and planned work; obtain engineering or legal advice where the records leave material uncertainty.

Strengthening Timeframes

An EPB notice states the deadline for completing seismic work. Base statutory periods depend on seismic area and priority status, but eligible deadlines that had not lapsed on 2 April 2024 were extended by four years, so use the current notice or EPB Register entry:

• Priority buildings: shorter base periods apply in high and medium seismic areas; confirm the reissued notice deadline
• Other buildings in high seismic areas: 15-year base period, subject to the current notice and applicable extension
• Other buildings in medium seismic areas: 25-year base period, subject to the current notice and applicable extension
• Buildings in low seismic areas: 35-year base period, subject to the current notice and applicable extension

An EPB notice can affect ownership decisions, but lending, insurance and value effects are provider- and property-specific. Confirm the notice deadline and obtain written lender, insurer and professional advice for the building.

What Does Strengthening Actually Cost?

Strengthening cost depends on the assessed vulnerabilities, design, target outcome, access, heritage constraints, consenting, temporary works and construction scope. National ranges are not reliable; obtain scoped current estimates.

• Engineering assessment and concept design: confirm scope, assumptions and professional fees
• Design, consent and enabling work: obtain project-specific estimates and contingencies
• Construction and associated work: obtain itemised quotes that reflect the building, access and approved design

For a unit title, do not divide the project cost by unit count. Check the body corporate levy resolution, relevant interests, financing, contingency and allocation documents.

Impact on Property Values and Insurance

An EPB notice and proposed work may affect a buyer’s assessment and a lender’s decision, but criteria vary. Obtain a current valuation and written lender confirmation for the property and planned work.

Insurance availability, premiums, excesses and exclusions are policy- and building-specific. Review the body corporate policy where relevant and obtain written insurer confirmation before committing.

Due Diligence When Buying

If you are considering purchasing an older apartment or unit, earthquake risk should feature prominently in your due diligence:

• Check the council's earthquake-prone building register for any current notices
• Request any existing seismic assessments from the body corporate
• Ask about planned or completed strengthening work and associated levies
• Ask an appropriately qualified engineer what assessment, if any, is proportionate to the available records and decision
• Factor potential strengthening costs into your purchase decision
• Confirm insurance availability and terms before going unconditional

Assessment scope and fees vary with the building and available information. For a unit title, check existing assessments and ask an appropriately qualified engineer whether further work is needed; obtain a written scope and fee estimate.

Moving Forward

Earthquake risk is a reality of living in New Zealand. For homeowners in standalone houses, the legal obligations are limited, but understanding your home's seismic performance remains worthwhile for insurance and peace of mind. For owners or prospective buyers of apartments and units, earthquake-prone building legislation creates real financial obligations that must be factored into property decisions.

If you have received an EPB notice, confirm the current register deadline and discuss the assessment and seismic-work options with the council, an appropriately qualified structural engineer, the body corporate and legal advisers as relevant.