The Natural Hazards Commission Toka Tū Ake (NHC) has released new Low Damage Seismic Design (LDSD) guidance intended to help buildings return to service more quickly after earthquakes, which may affect how insurers and risk managers assess property and business interruption exposure in New Zealand.
The LDSD series now includes volumes two and three. The new documents set out a voluntary framework that allows engineers, architects, and building owners to specify performance targets above Building Code minimums and to design specifically for functional recovery after major shaking.
Developed by industry specialists and co-funded by NHC and the Ministry of Business, Innovation, and Employment (MBIE), the guidance summarises research findings and post-earthquake experience in design material related to repairability and reoccupation.
The LDSD guidance is intended to respond to a central limitation of current practice: the Building Code is primarily structured around life-safety objectives and does not require that a building be usable or readily repairable after a severe earthquake. “While minimum code design protects lives, it doesn’t guarantee quick recovery,” said Professor Ken Elwood, joint chief engineer (resilient buildings) at MBIE and NHC.
Elwood points to the Canterbury and Kaikōura earthquakes as examples of this gap and its effects on occupants, businesses, and communities. “Canterbury and Kaikōura showed us that many buildings delivered on life safety but were too damaged to use, meaning that families were out of homes, and schools and businesses were closed for months. In Canterbury, widespread demolition and slow recovery added environmental and financial costs to the social disruption. Kaikōura reinforced that even modern, code-compliant buildings can be unusable for months,” he said.
Research funded by the NHC indicates that New Zealanders generally expect buildings to sustain less damage and return to function sooner than the minimum code performance currently provides. The LDSD series sets out structured ways for design teams and owners to define these higher performance objectives and select corresponding technologies and systems.
Volume one of LDSD, released in 2024, outlined low-damage strategies, described broad options, and provided guidance on how to begin adopting them. Volumes two and three move into greater technical depth, describing performance levels and detailed criteria that can be incorporated into design briefs, procurement documents, and project agreements.
The guidance is designed to sit alongside TS 1170.5:2025, a new Standards NZ technical specification that updates earthquake design loads based on the latest National Seismic Hazard Model. Used together, the documents are intended to inform both the seismic demand assumptions and the desired post-event performance of buildings. “The TS tells us how strong earthquakes could be in different parts of New Zealand, and LDSD shows how to design buildings that can handle such earthquakes and recover faster. Having these two pieces come out together is a big step forward for the industry,” Elwood said.
Neither LDSD nor TS 1170.5:2025 is mandatory. Both operate as voluntary references that owners, financiers, and insurers can request for projects designed to perform above the Building Code baseline, particularly for assets with high occupancy, critical services, or significant business interruption exposure.
LDSD forms part of NHC’s Resilient Homes and Buildings Action Plan and is available on the Design.Resilience.NZ website, which was developed by NHC, MBIE, Building Research Association NZ (BRANZ), and engineering technical societies. The Structural Engineering Society of New Zealand (SESOC) led the project, working with engineers, architects, researchers, and industry representatives.
The launch of the updated LDSD guidance comes as the government prepares legislative changes to the earthquake-prone building (EPB) system. A bill is expected in the coming months that would change the regime to place greater emphasis on higher seismic hazard regions and higher-risk building categories, and to lower compliance requirements in lower-risk settings.
Proposed measures include removing low-risk buildings and buildings in low seismic zones such as Auckland, Northland, and the Chatham Islands from the EPB system. New tiered risk-mitigation requirements would be introduced, reflecting updated engineering methods and varying by location and building type.
Under the proposals, building owners would be able to apply for extensions to strengthening deadlines to support staged remediation programmes. The government also plans to remove the blanket requirement to complete fire and accessibility upgrades at the same time as seismic work, which it says is intended to make strengthening projects more feasible for owners.
