The Earthquake-Prone Building Problem
Wellington’s building stock includes a significant number of older buildings that do not meet current earthquake performance standards. The Earthquake-Prone Building (EPB) provisions of the Building Act require that these buildings be identified, their owners notified, and a programme of strengthening or demolition undertaken within prescribed timeframes.
For structural engineers and construction contractors with the capability to carry out seismic strengthening work, the EPB programme represents a significant and sustained pipeline of work in Wellington. This market exists throughout New Zealand but is most concentrated in Wellington, where the earthquake risk is highest and the building stock includes many unreinforced masonry buildings that require strengthening.
What Earthquake-Prone Buildings Need
An earthquake-prone building is one assessed to perform at less than 34% of the New Building Standard (NBS) level in a major earthquake. The NBS is itself a high standard — a building at 100% NBS is designed to a performance level that life-safety engineers consider appropriate for modern construction. Buildings below 34% NBS have a materially higher risk of failure in a significant earthquake.
Strengthening an earthquake-prone building typically involves adding structural elements — shear walls, moment frames, base isolation — that increase the building’s ability to resist seismic loading. The engineering challenge is considerable: the strengthening solution must work with the existing structure, avoid creating new problems (soft storeys, plan irregularities), and be constructible within the occupied or partially-occupied building.
The Wellington Market
Wellington’s CBD contains a concentration of older commercial buildings, many in heritage categories, that require strengthening. The heritage status of many buildings adds complexity — the strengthening solution must preserve heritage fabric, and the consent process involves Heritage New Zealand in addition to the council. Contractors who understand how to work in heritage buildings, managing dust, vibration, and structural interventions with sensitivity to the existing fabric, are well-positioned for this market.
Building Your Capability
Seismic strengthening is specialist work. Contractors who want to participate in this market need to develop experience in the specific techniques involved — epoxy injection, carbon fibre wrapping, steel bracing installation, concrete shear wall construction — and in working within occupied or operational buildings where construction activities must be managed to minimise disruption. Building relationships with the structural engineering firms who design strengthening schemes is the primary business development pathway into this market.