When faced with seismic risk, building owners often assume demolition and rebuild is the only viable option. Under the current earthquake-prone building (EPB) system, the cost, complexity and uncertainty associated with strengthening existing buildings can make starting from scratch seem like the less risky route.
But there is growing pressure to retain and reuse our existing building stock – for both environmental reasons and to protect the character of our urban centres. And the government’s proposed changes to the EPB system – with a greater emphasis on actual life safety risk – could make remediation and reuse more realistic than it has been in the past.
As Prendos Director and Chartered Structural Engineer Cathy Thomas explains, whether repair or rebuild makes most sense still comes down to feasibility. Owners need to understand the actual seismic risk, the scope of work required and the commercial implications, before committing to a path that may be difficult to reverse.
Why remediation can stack up – especially under a more risk-based EPB system
One often-overlooked advantage of strengthening and refurbishing an existing building is that you’re not automatically forced to bring the entire asset up to today’s new-build standards. That’s because seismic work on an existing building is about managing risk, not achieving full compliance with modern building codes.
This isn’t about lowering standards or avoiding responsibility. It’s about recognising that existing buildings are assessed differently to new ones. In the right circumstances, that can allow owners to focus investment where it actually improves safety and performance.
In practical terms, that distinction can make a huge difference to cost. Cathy gives an example from a low-rise commercial building in Auckland where the owners chose a partial demolition and targeted remediation approach, rather than knocking the whole building down and starting again. Under today’s rules, some elements – like the foundations – wouldn’t meet current new-build standards if the building were being constructed from scratch.
“Those foundations wouldn’t actually comply these days,” Cathy says. “But that doesn’t matter, as long as they pass the assessment.”
If the same project had been treated as a new build, it would have triggered a far more complex (and expensive) set of requirements – including deeper geotechnical investigation and more costly foundation construction. By reusing and upgrading what already existed, the owners were able to focus investment on the parts of the building that genuinely affected safety and performance.
There’s another factor at play as well. As seismic hazard models and design guidance continue to evolve, new buildings are being designed to increasingly demanding standards.
“The seismic coefficients are going to increase,” Cathy notes. “So if you can reuse an existing building, the benefits are even greater.”
In short, remediation can offer a more proportionate, cost-effective pathway – provided the building is suitable, and the risks are properly understood.
The realities – and the “gotchas” owners need to plan for
Remediation isn’t a magic discount button. Cathy is clear that strengthening work often pulls other upgrades into scope.
“As soon as you’re doing strengthening work, you’re going to have to look at fire and services as well”, she says.
And because strengthening is invasive, a lot of cost sits outside the steel and concrete.
“Quite a lot of the cost of seismic upgrades is in floor coverings being lifted and linings coming off – that’s why it forces you to do quite a high level of refurbishment.”
In practice, many owners end up doing a near-complete refurbishment – especially when weathertightness issues or end-of-life building components are involved.
“Often there’s more than one driver, so you may as well do the whole thing.”
The upside? If done well, you can end up with a building that competes with new stock in terms of value and desirability to tenants. A fully refurbished building can often command the same market value as a new building.
Sometimes demolition is the right answer
Cathy is also realistic that not every building is worth saving.
“It really does depend a lot on the building type,” she says.
She describes seeing buildings that haven’t been meaningfully upgraded for decades, where the economics may simply not work – especially for owners without deep pockets. There are also location-driven cases where land value or redevelopment opportunity may outweigh refurbishment logic.
The key message for owners: don’t pick a path based on ideology. Make a decision based on properly assessed feasibility.
A pragmatic way to decide: assess, strategy, cost
For many owners, the hardest part of dealing with seismic risk is knowing which path is actually viable before committing serious money. Too often, owners assume there are only two options: do nothing or demolish and rebuild. In reality, the best approach can only be found by assessing the building properly.
Cathy gives a good example from a recent project in central Auckland. The owner had a mixed-use building, with retail at ground level and residential apartments above. After being issued an earthquake-prone building notice by the local authority, he assumed demolition was the only realistic option. The land value was high, and from his perspective, starting again seemed like the safest financial decision.
Once the building was properly assessed, the picture became more nuanced. Rather than defaulting to demolition, Cathy was able to work through the building’s issues in detail and develop a remediation approach that was technically robust and commercially realistic.
Her work showed the building could be strengthened and upgraded in a way that stacked up financially – and importantly, resulted in a far better-performing asset than the owner had before. The works could be staged, the building remained tenanted throughout, so rental income was maintained. What had initially appeared to be a marginal, high-risk asset became a significantly improved building with a clearer long-term future.
That’s the value of a structured early-stage approach: understand the risks, develop realistic options, and attach credible costs before locking yourself into an irreversible decision.
This is where Prendos can add real value for owners. A preliminary seismic assessment, paired with a high-level remediation strategy and QS costing, allows owners to properly test whether remediation, partial refurbishment, or redevelopment makes the most sense – financially, operationally, and environmentally – before committing to a path.
How Prendos can help: a packaged early-stage pathway
With the proposed EPB reforms on the horizon, this kind of early, structured decision-making becomes even more valuable. A less prescriptive system doesn’t remove risk – it shifts more responsibility onto owners to understand their buildings properly and make informed choices.
For owners weighing remediation vs rebuild, Prendos can package a preliminary seismic assessment + high-level remediation strategy + QS costing so you can make a commercial decision early – with the scope clearly defined and exclusions explicit.
The goal is simple: understand your building’s vulnerabilities, identify realistic remediation options, and attach credible costs – so you can decide whether to refurbish, repurpose or rebuild with confidence.
At Prendos, adding value to your assets is our number one priority. If you’d like to speak with our Structural Engineers about how they can help you maximise the value of your investments, call us on 0800 PRENDOS, email [email protected], or fill in the form below and we’ll call you back.
