Lessons learnt from the Canterbury earthquakes

As the building regulator, MBIE monitors current and emerging trends in the building sector, including the lessons to be learnt following the Canterbury earthquakes.

Risks associated with non-structural elements in seismic events

MBIE commissioned research relating to the earthquake performance of non-structural elements: two detailed reports, and small survey of 20 buildings in Wellington in Auckland.

  1. Estimating the Risk to Life Safety during Earthquake from Non-Structural Elements in Commercial Buildings in New Zealand [PDF 2.8MB]. Report by Beca.
  2. Economic Benefits of Code Compliant Non-Structural Elements in New Buildings [PDF 2.6MB]. Report by Opus.
  3. Survey of Seismic Restraint of Non-Structural Elements in Existing Commercial Buildings [PDF 2.2MB]. Survey by KOA.

Primary structure and falling masonry are the major contributors to loss of life in an earthquake and damage to non-structural elements would not appear to be a significant life safety issue based on findings from the research. MBIE considers that the combination of guidance issued by MBIE (practice advisory 19), industry-led initiatives and high profile failures in recent earthquakes have improved awareness of requirements to restrain non-structural elements. There is still room for improvement, particularly in the consent process, to ensure consistent achievement of building code objectives.

Built Environment Leaders Forum

A Built Environment Leaders Forum, held in September 2015, aimed to apply lessons from the Canterbury earthquakes to improve the way we manage risks from all natural hazards to New Zealand’s built environment.

Read about the Built Environment Leaders Forum, including a ‘Canterbury lessons’ background paper.

Earthquake repairs to Canterbury homes – Home inspection survey report (CEDAR)

MBIE commissioned an independent survey of the repairs to 101 earthquake-damaged Canterbury homes selected from more than 2,700 addresses provided by the Earthquake Commission (EQC), Housing New Zealand, and insurers Southern Response and IAG. The survey also included a small sample of houses where homeowners had opted out of an insurer-led home repair programme.

We initiated the 2015 survey to assess the Building Code compliance of structural repairs that were exempt from a building consent under Schedule 1 (repairs and maintenance) of the Building Act.

Exempt repair work was considered to have a greater risk of non-compliance as it is not subject to a council inspection and because, unlike cosmetic repairs, defects in structural repairs may be hidden from view and therefore harder for homeowners to identify.

The report found that 32 of the 90 homes that met the survey criteria had structural repair work carried out that was non-compliant with the Building Code. An additional 23 homes were assessed as having minor repair defects.

A key finding from the survey is that 30 of the 32 homes with non-compliant repairs involved floor re-levelling using the ‘jack and pack’ repair method. This is a relatively simple repair job when done correctly and properly supervised.

More complex structural repairs inspected in the survey were generally done well, which suggests some corners were cut on the smaller jobs and they lacked adequate supervision and oversight.

The report makes a number of recommendations for further review and that the issues identified are rectified.

Read the Home Inspection Survey Report and the full list of recommendations [PDF 722KB]

Read the frequently asked questions about the report [PDF 331KB]

MBIE’s Building Performance website can help you check if you need a building consent.

Structural performance of commercial buildings in the Canterbury earthquakes

MBIE sponsored a number of structural reports on the performance of commercial buildings in the Canterbury Earthquakes. These include reports commissioned by MBIE to support the work of the Canterbury Earthquakes Royal Commission.

These reports include:

Structural performance of Christchurch CBD building in the 22 February 2011 aftershock [PDF 10MB]

Technical investigation into the structural performance of buildings in Christchurch [PDF 1.5MB]

CTV Building Geotechnical advice [PDF 11MB]

CTV Building – Non-linear seismic analysis report [PDF 4.5MB]

Pyne Gould Corporation Building – Site Examination and Material Tests [PDF  4.3MB]

Investigation into the collapse of the Pyne Gould Corporation Building on 22 February 2011 [PDF 2.2MB]

Forsyth Barr Building Stairs – Site Examination and Materials Test [PDF 4.5KB]

Response to the Canterbury Earthquakes Royal Commission
 

You can find more reports in Publications and research.