Ensuring new buildings can withstand liquefaction risks

House surround by silt as a result of liquefaction.

Amendments from the November 2019 Building Code update ensure new buildings are built safe and strong enough to withstand liquefaction risks. Changes are already in place in the Canterbury region, and will now be extended to all of New Zealand.

Background

The November 2019 Building Code update made an amendment to the Acceptable Solution B1/AS1, so it cannot be used on liquefaction-prone ground. This amendment is a result of the experience of the Canterbury earthquakes and recommendations made by the Royal Commission of Inquiry.

The amendment requires robust foundations for liquefaction-prone ground which is already in place in the Canterbury region, and will now be extended to all of New Zealand ensuring new buildings are being built safely and strongly enough to withstand liquefaction risks.

This amendment will provide clarity to councils, Building Consent Authorities (BCA's), engineers and developers, resulting in safer and more resilient buildings.

Work in progress

Work is underway by the Ministry of Business, Innovation and Employment (MBIE) to develop framework and resources to implement a change to the Building Code's 'good ground'. The definition has been updated to encourage hazard mapping throughout New Zealand to avoid the risk of buildings being built on liquefiable ground.

New Zealand Standard B1/AS1 - standards.govt.nz

To help prepare councils, BCA's, engineers and developers for when this amendment comes into effect in November 2021, MBIE is providing support by:

  • providing clarity to councils, building consent authorities (BCA's) and engineers when designing for liquefaction-prone ground,
  • undertaking a review of what information exists on liquefaction hazard mapping across New Zealand,
  • developing flowcharts to show the pathways (and roadblocks) for those stepping through the building consenting process after 28 November 2021,
  • developing a summary for the assessment of liquefaction vulnerability in accordance with the MBIE/MfE guidance (2017),
  • identifying more opportunities to provide information and education,
  • engaging with regional and local councils around New Zealand.

This will help councils, BCA's and designers across New Zealand have a thorough understanding of the 'good ground' change and mapping liquefaction-prone ground. This will help support consistent application and enforcement across New Zealand when the changes come into effect after 28 November 2021 .

To help you complete mapping of liquefaction prone ground, we need to understand how far through the process each council is. To do this, we want those responsible for hazard mapping, implementation of the RMA and processing building consents to complete a short survey.

Begin survey

Legal requirements

Regional and local councils have a legal requirement under the Resource Management Act to complete hazard mapping in their local jurisdiction and comply with the Building Code for buildings which are built on liquefaction-prone ground.

Resources

Resources are coming soon.

For more information on the amendment to the Acceptable Solution B1/AS1, please contact the Building Performance team at info@building.govt.nz.

This information is published by the Ministry of Business, Innovation and Employment’s Chief Executive. It is a general guide only and, if used, does not relieve any person of the obligation to consider any matter to which the information relates according to the circumstances of the particular case. Expert advice may be required in specific circumstances. Where this information relates to assisting people: