Overview of TC1, TC2 and TC3 technical categories
On this page:
- TC1, TC2, and TC3
- Technical category "not applicable"
- Fact sheets
- TC3 residential rebuild booklet
- TC3 residential action plan
- Video: RibRaft TC3 Foundation Solution
- Video: TC3 Residential Rebuild Discussion
- Video: Green zone changes - what they mean for you
- Video: EQC talks about TC3
- Video: Insurers talk about TC3
- Video: Christchurch City Council talks about TC3
- Radio interviews and adverts
- Questions and answers
Land in the green zone has been divided into three technical categories – TC1 (grey), TC2 (yellow) and TC3 (blue). These categories describe how the land is expected to perform in future earthquakes, and also describe the foundation systems most likely to be required in the corresponding areas.
- Technical Category 1 (TC1, grey) – future land damage from liquefaction is unlikely. You can use standard foundations for concrete slabs or timber floors.
- Technical Category 2 (TC2, yellow) – minor to moderate land damage from liquefaction is possible in future significant earthquakes. You can use standard timber piled foundations for houses with lightweight cladding and roofing and suspended timber floors or enhanced concrete foundations.
- Technical Category 3 (TC3, blue) – moderate to significant land damage from liquefaction is possible in future large earthquakes. Site-specific geotechnical investigation and specific engineering foundation design is required.
As this is an area wide classification, site specific geotechnical work will be required to determine the actual foundations required for each house in TC3 areas. In some cases this will mean TC2 level foundations will be enough in TC3 areas based on actual ground tests. This approach is common throughout New Zealand.
It is important to note that property owners only need to replace their foundations if their house needs to be rebuilt, or requires repairs to the foundations. Otherwise, no further action is needed (until you undertake major renovations that affect your foundations).
Information about foundation requirements is available on the Ministry of Business Innovation and Employment’s Building and Housing Group website.
Non-residential properties in urban areas, properties in rural areas or beyond the extent of land damage mapping, and properties in parts of the Port Hills and Banks Peninsula have not been given a Technical Category ("technical category not applicable").
Normal consenting procedures will apply in these areas.
Technical category 1 (TC1) fact sheet [PDF 255KB]
Technical category 2 (TC2) fact sheet [PDF 255KB]
Technical category 3 (TC3) fact sheet [PDF 255KB]
Technical categories and your property [PDF 880KB]
This booklet, published December 2011, provides information to guide your decisions when repairing or rebuilding your property. It has has been prepared by CERA and other agencies working on Canterbury earthquake recovery to better inform residential property owners about the technical categories and what they mean.
Download the booklet:
TC3 residential rebuild [PDF 1.5MB]
This booklet provides answers to some of most commonly asked questions about the Canterbury residential rebuild, particularly about technical categories in the residential green zone.
The information contained is freely available from various other sources such as the Earthquake Commission (EQC), the Ministry of Business Innovation and Employment’s Building and Housing Group (Building & Housing) and the Christchurch City Council.
We encourage you to read the information and follow the links to the various supporting agencies.
Booklets can be ordered by calling 0800 RING CERA (0800 7434 2372) or emailing firstname.lastname@example.org
In March 2013, CERA and MBIE hosted a workshop with technical experts to discuss issues and actions to support the residential rebuild. The workshop was part of ongoing communications and stakeholder engagement to support the residential rebuild and recovery which included an initial workshop at the end of October 2012.
Approximately 100 people attended the workshop including attendees from various technical and professional sectors such as lawyers, valuers, lenders, consenting agencies, engineers, building companies, government agencies, insurers and real estate agents.
The objectives of the March workshop were to:
- Report back on progress since the October workshop on topics such as developing reliable information for homeowners and case studies for TC3 land
- Develop a shared understanding of how the rebuild was progressing
- Identify barriers with and between the technical and professional sectors and actions that will overcome these and accelerate the residential rebuild
- Facilitate collaboration and information sharing across sectors.
As a result of the workshop, the Residential Recovery Action Plan was developed [PDF 100KB]
In October 2012 Canterbury Earthquake Recovery Authority held a Residential Recovery Workshop to identify solutions and remove barriers to rebuilding residential properties and commercial activity in Technical Category 3 (TC3) areas.
The result of the workshop was the creation of an Action Plan which contains several initiatives that will impact homeowners:
- A rigorous programme of engagement with property professionals aimed at giving them the tools to better inform homeowners about TC3 issues (CERA),
- ‘Proof of Concept’ demonstration projects (CERA, HCNZ and others),
- The development of a more comprehensive information portal to guide both industry and residents to the right place and the best information, guidance and support that they need (CERA with MBIE)
The Action Plan [PDF 135KB]
Workshop Proceedings document [PDF 289KB]
(Details the summary of the pre workshop questionnaires and the discussion on the day of the workshop)
PDF versions of the technical categories maps (as at 23 March 2012):
- Canterbury Land Information Map - Kaiapoi Lakes to Governors Bay [PDF 1.8MB]
- Department of Building and Housing Residential Foundation Technical Categories [PDF 1.4MB]
30 April 2013
A demonstration of an enhancement to the Firth RibRaft foundation solution, which has been used in New Zealand for many years. The RibRaft range has been extended to include a solution for TC3 ground conditions. This video shows one of the first of these foundation solutions being installed on a TC3 site in Christchurch.
12 December 2012
Hosted by Roger Sutton CERA chief executive and Kineta Knight, CTV
A panel made up of representatives from the relevant agencies - Insurance Council, City Council, Southern Response and Ministry of Business, Innovation and Employment - who discuss the questions and topics that have been posed by people in the community at the meetings held across the city.
CERA also called for additional questions last week through the media and through Cancern to ensure that all of the areas covered in the hour-long session were the most appropriate.
This production was put together by CERA and CTV, and was originally broadcast on CTV on 12 December 2012
As part of the ongoing information sharing process, CERA has produced a half-hour discussion panel to cover some of the key issues around the Green Zone changes, particularly the new Technical Categories.
The discussion is facilitated by CERA chief executive Roger Sutton and involves Reid Stiven from EQC, Malcolm McMillan from the Department of Building and Housing, Mike Jacka from Tonkin and Taylor, and Dean MacGregor from IAG Insurance.
This production was put together by CERA and CTV, and was originally broadcast on Maori Television on Saturday 19 November 2011, and CTV on Sunday 20 November 2011. This production was made with technical assistance from TV3.
EQC Manager of Customer Services, Bruce Emson, talks about EQC's approach to:
- The TC3 drilling programme, its progress, availability of rigs and drilling processes
- Drilling data
- Who pays for foundation damage
- The EQC claims management process
- Land information packs
- How EQC will settle land claims
For more information visit: EQC
Insurers, Rene Walker (IAG) and John McSweeney (Southern Response), discuss:
- Future insurance in Christchurch
- Repair/Rebuild costs for TC3 Foundations
- Demolition of houses
- Timelines and prioritisation of repairs
- Buying an earthquake damaged house
- Claim settlement options
For more information visit:
Peter Mitchell, General Manager Regulation and Democracy Services at the Christchurch City Council, talks about:
- Flood Management Areas
- New floor levels
- Damaged roads and sewage systems
- Technical Categories and LIMS
- Building on TC3 land
For more information visit:
- Christchurch City Council - Floor levels
- Christchurch City Council - Floor levels update [PDF]
- SCIRT (Stronger Christchurch Infrastructure Rebuild Team)
Interview: CERA chief executive Roger Sutton talks about technical categories (22 November 2011)
Download the interview [MP3 3.25MB]
A three minute interview with CERA chief executive Roger Sutton, that ran in November 2011 on the Breeze radio station. Roger answers some of the most commonly asked questions about residential green zone technical categories.