What is a Tech Category (TC) and why does it matter in Canterbury?
Short answer
After the 2010-2011 Canterbury earthquakes, every Canterbury section was given a Technical Category (TC1, TC2, or TC3) based on liquefaction susceptibility. TC1 means standard foundations. TC2 needs some engineering. TC3 needs significant foundation engineering — adding $30-90k+ to a build. Always check the TC on the LIM before committing to a Canterbury build.
Source: MBIE — Canterbury Tech Category guidance. Updated May 2026.
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Check a builderKey facts
- TC1 — most ground; standard foundations OK
- TC2 — moderate liquefaction risk; some engineering
- TC3 — high liquefaction risk; engineered foundations required
- Categories apply to land within the Canterbury Earthquake recovery zone
- On LIM and in title information
Foundation costs by TC
TC1: standard slab on grade or basic ribraft — $40-70k for a house of average size, included in normal builder quotes.
TC2: ribraft slab with engineering, often reinforced — $60-90k.
TC3: ribraft with deep edge beams, screw piles, driven piles, or RibRaft FFS — $80-180k depending on geotech. Always engineer-designed.
Geotech is the deciding factor
TC3 land needs site-specific geotech investigation (boreholes, CPT testing) to design the right foundation. Geotech costs $3-8k. The geotech report drives the foundation, which drives the budget.
Some TC3 sites are perfectly fine to build on; others would be uneconomic. Don't commit to a section without seeing geotech.
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Related questions
Sources: MBIE — Canterbury Tech Category guidance; Christchurch City Council. General information for NZ homeowners, not legal advice. Building rules change and vary by council, so confirm critical details on the official source before acting. Last updated 2026-05.