New Zealand’s geology is unique with numerous fault lines making us one of the most earthquake-prone countries in the world – with the potential to damage our buildings and infrastructure.
For building owners, seismic strengthening is a regulatory requirement if your building is deemed earthquake prone. However, it’s more than that. It’s also about protecting your investment, giving peace of mind to tenants, purchasers, insurers and stakeholders while, most importantly, ensuring people can safely exit the building if something goes wrong.
Local authorities identify commercial buildings that are potentially earthquake prone within their district based on many factors including age, construction type, size and height, and they can do this at any time if they have reason to suspect the building may be earthquake prone.
Many property owners in the South Island, especially those with older masonry (brick, block or stone) buildings, that have no apparent form of reinforcement, are considered more at risk – and you will have likely been requested to assess the earthquake strength of your building/s.
As an example, the Canterbury earthquakes were a stark reminder of how vulnerable older masonry commercial buildings can be – some partially or fully collapsed, leaving them untenantable and causing loss of income for owners.
For many owners, especially those in smaller towns, the idea of strengthening works that might follow can feel daunting, and many often question how they can afford it. However, these buildings carry higher risks, and securing insurance for your key asset is likely to get more expensive or harder to get if strengthening is not undertaken.
Step 1: Understand your obligations: Visit MBIE’s Building Performance site for EPB guidelines and deadlines. Buildings may be classified as potentially earthquake-prone under the EPB Amendment Act 2016. If your building is identified, your council has, or will, likely request a seismic assessment under the Building Act (Section 133A). If this is the case, talk to them to understand the timeframes for both assessments and strengthening.
Step 2: Engage an expert: Choose an engineer experienced in seismic assessments and strengthening. They will assess your building to determine its seismic strength in terms of %NBS (percentage of New Building Standard). If your building scores below 34%NBS, it’s considered earthquake-prone and strengthening is legally required. Note that if your property shares walls with another building, you may need to work collaboratively.
Step 3: Plan and budget: Strengthening can be costly, therefore discuss potential solutions with your engineer.
Step 4: Consent and compliance: Any strengthening work must comply with the Building Code and requires building consent from your local council. This may also trigger upgrades and compliance to fire escape routes and accessibility and facilities for persons with disabilities.
Step 5: Seismic strengthening: This involves adding or improving structural elements to improve the building’s performance during an earthquake and increase the %NBS. Common strengthening techniques include:
Step 6: Complete within the timeframe: Repairs and strengthening must be completed within a set timeframe. This is set by the local council and depends on whether the area is considered high, medium or low risk. For example, buildings with unreinforced masonry in certain thoroughfares may be considered a priority, with strengthening potentially needing to be completed in 7.5 years in high seismic risk areas or 12.5 years in medium seismic risk areas.
Seismic strengthening is not just about compliance – it’s about resilience and life safety. By taking proactive steps, small commercial building owners can protect their investments and contribute to a safer built environment in New Zealand.
With four South Island offices, including in Christchurch, we have worked extensively with owners to develop pragmatic solutions to what is in some instances, a complex process.
Davis Ogilvie (DO) is a multidisciplinary consultancy that provides comprehensive engineering, surveying and planning services, as well as specialist expertise in civil, geotechnical and structural engineering, resource management and environmental sciences.
With a legacy of over 90 years, we have a wealth of local knowledge and experience, with South Island offices in Christchurch, Nelson, Greymouth, and Timaru. Whether it is a multidisciplinary or a standalone project, we can help.
From dirt to development, resilience to recovery, DO provides collaborative efficient solutions. DO delivers.
