TC3 foundations, Christchurch.
A TC3 section is not a dead end. It is a ground problem with engineered answers, and pricing one starts with a conversation, not a panic.
What TC3 actually means.
TC3 is the technical category for ground that moved and could move again. Liquefaction risk, mainly. It does not mean you cannot build; it means the foundation has to be designed for the ground's behaviour, usually with specific engineering input, sometimes with ground improvement or piles under it.
A re-levellable foundation is the pragmatic Christchurch answer: an engineered system built so that if the ground does move again, the house can be brought back to level. A repair, not a rebuild. Which system suits your section is a geotech and engineering question, and we work through it with the engineer as part of running the job.
The honest part: some TC3 sections are expensive to build on, and you deserve to know that before you own one. Ring first. The advice is free.
- The category
- Ground that moved
- The answer
- Engineered, re-levellable
- The input
- Geotech + engineer
- The call
- Free, before you buy
What ignoring TC3 costs.
The expensive TC3 stories all share one shape: the ground question got answered late. A section bought unconditionally before anyone read the geotech. A standard raft consented on hope and stopped at review. A repair that became a rebuild because nothing under the house was built to be re-levelled.
None of that is bad luck. It is sequencing. Answer the ground first and TC3 is an engineering job like any other; answer it last and it prices itself.
- The geotech read after purchase instead of before.
- A standard system consented on hope, stopped at review.
- Ground improvement discovered mid-programme, not priced up front.
- A repair that costs like a rebuild because nothing was re-levellable.
Who stands behind it.
Starting as a qualified carpenter.
With the engineering documentation at handover.
Christchurch first, and the wider Canterbury area.
On every site we run.
Engineered ground, on real sites.
The systems TC3 calls for are the ones we already build: engineered block, tanking, stepped slabs.
Engineered block on the hill
Stepping with the ground
Tanked and stepped
Split-level slab, membrane down
Rural new build
Engineered footings
Tight-access infill
Two slabs down
How a TC3 job runs.
Same spine as every job, with the ground work moved to the front where it belongs.
The section conversation
Before you buy if possible. What the ground there has done, what that usually means, what it could cost. Ten minutes, free, before you commit.
Geotech and engineering
The geotech report read properly, the engineer engaged, the system designed for what the ground actually is, not what the listing hoped.
The build
Ground improvement or piling where the design calls for it, then the engineered foundation. Coordinated, inspected, poured and finished like every job we run.
Handed back, documented
LBP signed off, engineering documentation with the handover. The paper trail matters more on TC3 than anywhere, and yours arrives complete.
TC3 questions.
Can I build on a TC3 section at all?
Almost always, yes, with the right engineering. The real question is cost: the ground work on a hard TC3 section can cost serious money before a slab exists. That is exactly why the free call before you buy matters.
What does a TC3 foundation cost?
Honestly: it depends on the geotech, which is why there is no from-rate on this page. What we will do is read your geotech report with you, price the system the engineer designs, and tell you if the section is a money pit.
What does the engineer actually decide?
The foundation system itself: whether the ground needs improvement or piles, how the raft or re-levellable system is detailed, and what the council needs to see. Our job is to feed them a properly prepared site and build exactly what they draw, inspected at every hold point.
Do you handle the engineer, or do I?
We do. If you already have one, we work to their design; if not, engaging one is part of the job. Either way, the coordination runs through Mark: geotech, engineer, council, build.
Got a TC3 section? Ring first.
Ten minutes with Mark about what the ground there means. Then, if it stacks up, email the plans and price it properly.
Details, then the drawings.
PDFs or photos of the drawings are both fine. Everything sent here lands with Mark himself.