Plan Change 120: Why "On Paper" Deals Are Now Dangerous
By Deane Consultancy
Plan Change 120 has created a new kind of investment risk — one that isn't always visible upfront.
Some of the best-looking deals on paper are now the most dangerous in reality.
The New Gap: Planning vs Reality
PC120 creates a disconnect between **planning potential** (what zoning allows) and **delivery reality** (what engineering makes possible).
This gap is where investment risk now lives — and it's widening.
Where Risk Now Sits
Under Plan Change 120, risk has shifted into three areas that don't show up in a basic feasibility spreadsheet:
**Technical Risk** - Infrastructure capacity (can the network handle it?) - Stormwater management requirements - Site servicing and access constraints
**Environmental Risk** - Flooding and hazard overlays reducing buildable area - Build limitations tied to coastal or stability zones - Increased compliance requirements
**Financial Risk** - Mitigation costs that weren't in the original numbers - Reduced yield from constrained site coverage - Feasibility that no longer stacks up once constraints are factored in
Why This Is a Problem for Investors
Previously, you could rely on consultants to identify constraints later in the process — during detailed design or consenting. The risk was manageable because exit options remained open.
Under PC120, that approach is no longer safe.
**You need technical validation before acquisition.** Because once you commit: - Risk becomes fixed in the purchase price - Exit options reduce - Exposure increases significantly
The Rise of "False Positive" Deals
We are seeing more sites that look highly profitable in initial feasibility — strong yield on paper, good zoning, reasonable purchase price — but fail under detailed engineering review.
These are false positives, and they are becoming more common as PC120 constraints are applied across Auckland.
A site that "works" on a spreadsheet, but only if no stormwater detention is required, no flood modelling applies, and ground conditions are straightforward, doesn't actually work.
A Smarter Investment Strategy
To reduce risk under Plan Change 120, investors should:
- **Conduct engineering due diligence before exchange** — not after
- Validate key assumptions (stormwater, servicing, access) before committing capital
- Stress-test feasibility against realistic constraint scenarios
- Treat pre-purchase technical review as part of the acquisition cost, not an optional extra
If a deal only works without constraints, it doesn't work.
Deane Consultancy Perspective
We help investors bridge the gap between what a site promises and what it can actually deliver.
Our pre-purchase feasibility assessments give you a clear picture of: - What constraints apply under PC120 - What those constraints cost to mitigate - Whether the deal still stacks up once real engineering is factored in
Our goal is simple: remove uncertainty before it becomes cost.
**Plan Change 120 hasn't removed opportunity — it has made it more complex.**
The best investments are no longer the ones that look good first. They're the ones that hold up under scrutiny.
*This is the third in a three-part series on Plan Change 120. Read [Part 1 (Developer Risk)](/blog/plan-change-120-developer-risk-auckland) and [Part 2 (Property Owner Impact)](/blog/plan-change-120-property-value-impact-auckland).*
Our Engineering Services
- Geotechnical Engineering — Site investigations, foundation design & slope stability
- Structural Engineering — Residential & commercial structural design
- Civil Engineering — Earthworks, subdivision & resource consent support
- Stormwater & Wastewater — Detention design & flood risk assessment