That spacious deck, the double garage, the sleep-out at the back of the garden — they all look great. But if any of them were built without a building consent, they become your legal problem the moment settlement completes. Councils can and do pursue new owners for unpermitted work they inherited.
The good news: with the right checks, unpermitted work is usually detectable before you commit to a purchase.
Why Unpermitted Work Is Such a Big Deal
In New Zealand, most significant building work requires a building consent from your local council before it can begin. Consent ensures the proposed work meets the Building Code — covering structural integrity, weathertightness, fire safety, and more. When work is done without consent, there's no inspection, no sign-off, and no assurance it was built correctly.
The legal implications are serious. Under the Building Act 2004, councils have enforcement powers that follow the property, not the person who did the work. If the previous owner built a bathroom extension without consent five years ago, and you buy the property today, you become responsible for resolving it.
Section 164 of the Building Act allows councils to issue a notice to fix to the current owner regardless of who carried out the original work. There is no statute of limitations that protects buyers. A building that has been there for 20 years can still be the subject of enforcement action.
What Requires a Building Consent in NZ?
Not all building work requires consent — but anything structural or that changes the building's envelope almost certainly does. Consent is required for:
- New dwellings, additions, and extensions of any size
- New garages, carports, and sheds over certain dimensions (generally over 10m² if they're within 1m of a boundary, or any outbuilding that includes plumbing)
- Decks and verandahs higher than 1.5m above ground level
- Retaining walls over 1.5m high (or less if supporting a structure or surcharge)
- Removal or alteration of load-bearing walls
- New plumbing, drainage connections, or relocation of sanitary fixtures
- Installing a woodburner or solid fuel heater
- Swimming pools (fencing consent also required)
Work that generally does not require consent includes like-for-like replacements (a new kitchen sink in the same location), minor repairs and maintenance, and some small outbuildings under specific thresholds. When in doubt, check with your local council — they provide free pre-application guidance.
If it wasn't there when the house was originally built, and it cost more than a few thousand dollars, it almost certainly required a building consent. Apply this test to any structure or alteration you notice at a property.
The 6 Red Flags for Unpermitted Work
Train yourself to notice these warning signs during any property inspection:
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Structures not matching the council's floor plan The LIM report often includes council-held plans or site diagrams. If the deck, garage, or sleep-out shown physically at the property doesn't appear in those plans, it was likely built without consent.
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Work that looks newer than the house A fresh concrete floor in a 1960s garage, weatherboards that don't match, or a bathroom with clearly more modern fittings than the rest of the house all suggest work was done after the original build — and may not have been consented.
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Unusual ceiling heights, wall thicknesses, or finishes Consented work is built to code. Unpermitted work often reveals itself through non-standard construction: a wall that's too thin, a room with lower-than-standard ceiling height, or insulation that doesn't meet current requirements.
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Consents in the LIM with no Code Compliance Certificate (CCC) A consent without a CCC means work was started with permission but never inspected to completion. This is different from fully unpermitted work but raises similar questions about quality and compliance.
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Sleep-outs, studios, or minor dwellings Separate habitable buildings at the rear of a property are very commonly built without consent, particularly when converted from a garage or shed. Check carefully whether any secondary structure is consented for habitation.
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Owners who can't produce original plans or consent documentation A vendor who built an extension themselves and "thinks it was consented" or "can't find the paperwork" is a yellow flag. Consented work generates a paper trail — if it doesn't exist, the work may not have been consented.
How to Check Systematically: A 4-Step Process
The LIM lists every building consent ever issued for the property. Note the date, description, and whether each consent has a corresponding Code Compliance Certificate (CCC). Create a list of all consented structures and compare it to what you see physically at the property.
On your inspection, systematically note every structure present: main house, any additions, garage, carport, deck, pergola, sleep-out, shed, pool, retaining walls. Photograph each one. Then check each against the consent history in your LIM.
When you book a building inspector, ask them explicitly to flag any structures or work that appears inconsistent with standard consented construction. A good inspector will cross-reference physical evidence with what's expected for the age and type of property.
If you have a specific concern, you can call your local council directly and ask about a property's enforcement history. Ask: "Are there any outstanding notices to fix or compliance orders on this property?" This is public information and they must disclose it.
What It Costs to Fix Unpermitted Work
The cost of resolving unpermitted work varies dramatically depending on the complexity of the work and whether it can be retrospectively consented:
| Type of Unpermitted Work | Typical Resolution Cost | Risk Level |
|---|---|---|
| Simple deck or pergola (under 1.5m, low risk) | $2,000–$5,000 | Medium |
| Garage conversion to habitable room | $5,000–$25,000+ | High |
| Sleep-out or secondary dwelling | $10,000–$50,000+ | High |
| Structural wall removal (unengineered) | $15,000–$60,000+ | High |
| Unconsented plumbing (bathroom, kitchen) | $8,000–$30,000+ | High |
| Retaining wall (no engineer sign-off) | $5,000–$40,000+ | High |
These costs include council fees for certificate of acceptance applications, engineer reports (often required), possible remediation work to bring the structure up to code, and inspection fees. In some cases where the work simply cannot be brought up to code, the only option is demolition — which adds further cost.
Retrospective Consent: When It's Possible (and When It Isn't)
New Zealand councils can issue a Certificate of Acceptance (COA) for work done without consent, provided the work meets current building code requirements. This is the most common resolution path for uncomplicated unpermitted structures.
However, the COA process has limitations. The council can only certify what they can inspect — if work is hidden behind wall linings, the council will typically require those linings to be opened up so the structure can be assessed. If the work doesn't meet current code (not just the code at the time it was built), you'll need to remediate before a COA can be issued.
For complex or significant unpermitted work — particularly structural alterations or secondary dwellings — an engineer's report is almost always required as part of the COA application. This adds cost and time.
Unpermitted work can also affect your insurance. Many home insurers ask whether any alterations have been made to the property, and whether they were done with consent. Undisclosed unpermitted work can be used to decline a claim. Check with your insurer before going unconditional if unpermitted work is identified.
What to Do If You Find Unpermitted Work
Finding unpermitted work doesn't automatically mean you should walk away — but it does mean you need a clear-eyed assessment of the risk and cost before you commit.
Step 1: Get a council pre-application consultation. Before going unconditional, call the council's building compliance team and describe the work in question. Ask whether they would be likely to issue a Certificate of Acceptance and what the process would involve. This is free and gives you a realistic sense of the resolution pathway.
Step 2: Get a cost estimate. Commission a quantity surveyor or licensed builder to estimate the cost of bringing the work up to code or, in the worst case, removing it. This becomes your negotiating number.
Step 3: Negotiate with the vendor. Use the estimate to negotiate a price reduction or request the vendor resolve the issue before settlement. Many vendors aren't aware their property has unpermitted work — they may be willing to cooperate once the issue is surfaced.
Step 4: Consider a vendor warranty. Ask your lawyer to include a clause in the S&P agreement requiring the vendor to warrant that all building work was carried out with consent and that no council enforcement actions are outstanding. This provides contractual recourse if something emerges post-settlement that wasn't disclosed.
Step 5: Walk away if the risk is unquantifiable. If the scale of unpermitted work is large, hidden, or the vendor refuses to engage, use your due diligence condition to cancel and recover your deposit. This is the right call when the downside is open-ended.
- LIM consent history cross-checked against physical structures on site
- Building inspector asked specifically about non-consented work
- Council called to confirm no outstanding enforcement notices
- Cost estimate obtained for any identified unpermitted work
- Insurance position confirmed with your broker
- Vendor warranty or price adjustment negotiated if needed
How Unpermitted Work Affects Your Finance and Insurance
Unpermitted work isn’t only a council problem — it can directly affect whether you can finance and insure the property at all. This is the part buyers most often overlook.
Your lender may refuse to advance funds
When your bank arranges a registered valuation, the valuer notes anything that looks non-compliant or unconsented. A consent without a Code Compliance Certificate, or a structure with no records at all, can lead the lender to reduce the amount they will lend, hold back funds until the issue is resolved, or decline the loan on that property entirely. If your finance is conditional, an unpermitted-work flag can unravel the whole deal.
Insurers can decline cover or a claim
Most home insurers ask whether alterations were carried out with consent. Undisclosed unpermitted work gives an insurer grounds to decline a future claim — which, in turn, can breach your mortgage conditions, since lenders require the property to be insured. The risk compounds: no insurance can mean no mortgage.
If unpermitted work surfaces during due diligence, sort out the finance and insurance position before you go unconditional. Ask your broker to confirm the property is insurable as-is, and check with your lender that the valuation won’t hold back funds. Doing this after settlement leaves you exposed with no negotiating power.
Real-World Example: The $38,000 Garage Conversion
Consider a common scenario. A buyer falls for a tidy three-bedroom home with a converted garage used as a fourth bedroom and a home office. It is lined, carpeted, heated — it looks like part of the house. The buyer skims the LIM, sees a long consent history, and assumes everything is in order.
After settlement, they apply to refinance. The new bank’s valuer notices the “fourth bedroom” has no consent and no Code Compliance Certificate. The council confirms the garage conversion was never consented. To legalise it, the owner needs an engineer’s report, has to open up the linings for inspection, upgrade the insulation and fire separation to current code, and pay for a Certificate of Acceptance. The total: around $38,000 — money that came straight out of their own pocket, with no vendor to share it with.
The warning signs were all there in the LIM: a habitable room that didn’t match the consented floor plan, and no CCC for the conversion. A 20-minute cross-check of the LIM against the physical structures — or one question to a building inspector — would have surfaced the issue while the buyer still had the power to negotiate a price reduction or walk away.
The lesson isn’t that a converted garage is always a dealbreaker. It is that the time to find out is before you go unconditional, while the cost is still the vendor’s problem to solve — not yours.
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Analyse My Documents →Frequently Asked Questions
Any building work that required a consent under the Building Act 2004 but was done without one. This includes additions and extensions, new garages, decks over 1.5m high, structural alterations, retaining walls over 1.5m, and new plumbing connections. Minor like-for-like replacements generally don't require consent, but anything structural or that changes the building's envelope almost always does.
Order a LIM report from your local council — it lists all building consents ever issued for the property. Compare the consented structures against what physically exists at the property. Structures present without a corresponding consent in the LIM are a red flag for unpermitted work. A building inspector can also help identify work that appears inconsistent with consented construction.
As the new owner, you inherit full legal responsibility. The council can require you to legalise the work (obtain retrospective consent, which requires the work to meet current building code) or remove it entirely. Costs range from a few thousand dollars for simple retrospective consent to tens of thousands for complex remediation or demolition.
Yes, in many cases. Councils can issue a Certificate of Acceptance (COA) for work done without consent, provided the work meets current building code standards. However, if the work is hidden behind linings, the council may require them to be opened for inspection. If the work doesn't comply with current code, you'll need to bring it up to standard before a COA can be issued.
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