Residential Rebuild on TC3 Land – Christchurch

This Christchurch residential site was heavily affected by the Canterbury Earthquake Sequence, with significant liquefaction-related land damage, more than 100 mm of floor level variation across the dwelling, and extensive cracking to the foundation and building. A rebuild was required.

The site presented a number of challenges typical of TC3 land, including high liquefaction susceptibility, shallow groundwater, and soft soils at shallow depth. The client wanted a replacement foundation solution that would provide improved resilience in future earthquakes while retaining a timber floor to match the feel of the original home.

Cook Costello provided the geotechnical and structural engineering input needed to develop a practical, buildable and resilient solution for the site. Our work included:

• Ground investigations to define the subsurface profile and confirm liquefaction and soft soil hazards

• Design of shallow ground improvement measures to help mitigate the effects of liquefaction and soft near-surface soils

• Structural analysis and design of a robust timber floor foundation system suited to the site conditions

• Construction support and site involvement to help manage installation risks and ensure the works achieved the design intent

  
  

The result was a code-compliant residential foundation solution tailored to the site constraints, the client’s preferences, and the realities of building on TC3 land. By combining ground improvement with a robust and practical structural system, the rebuilt home was designed to better tolerate liquefaction-related ground movement and to be more readily relevelled after future significant earthquake events.