Building a retaining wall without the required council consent is a serious issue in New Zealand — one that can cost you far more in the long run than getting the paperwork sorted upfront. Whether it's an existing wall you've inherited or one you're planning, understanding the rules could save you significant stress and money.
Does Every Retaining Wall Need Building Consent?
Not always — but the exemptions are narrower than many homeowners assume. Under Schedule 1 of the Building Act 2004, some retaining walls are exempt from requiring a building consent. As a general guide, a retaining wall that retains no more than 1.5 metres of ground and does not support any surcharge (such as a driveway, building, or slope above) may be exempt.
However, this is not a blanket rule. Factors that can push a wall into consent territory include:
- Wall height exceeding 1.5 m
- Proximity to boundaries, buildings, or drainage
- Unstable or sloping ground conditions
- The wall supporting a load (surcharge) above it
- Specific district plan rules in your local council area
Always check with your local council before starting work. What's exempt in one district may require consent in another. You can also find general guidance at MBIE Building Performance.
What Are the Consequences of Building Without Consent?
If a retaining wall required consent and was built without it, the consequences can be significant:
1. It Becomes an Illegal Building Work
Illegal building work is defined under the Building Act 2004 as work carried out without the required consent. Councils have the power to issue a Notice to Fix, requiring you to either obtain retrospective consent (if possible) or remove the wall entirely — at your own cost.
2. Fines and Enforcement Action
Councils can issue infringement notices and pursue enforcement action. Fines can apply to both the homeowner and the tradesperson who carried out the work. In serious cases, the matter can be referred to the courts.
3. Problems Selling Your Property
This is where many homeowners get caught out. When you sell your home, your solicitor and the buyer's solicitor will review LIM reports and council records. An unconsented retaining wall will show up — or its absence from records will raise red flags. Buyers may:
- Demand the wall be legalised before settlement
- Reduce their offer to account for the risk
- Walk away from the sale altogether
4. Insurance Issues
If an unconsented retaining wall fails and causes damage — to your property, a neighbour's property, or a person — your insurer may decline the claim on the grounds that the structure was not legally compliant.
5. Liability for Damage or Injury
A retaining wall failure can be catastrophic. If the wall was built without consent and without proper engineering, you could be personally liable for any resulting damage or injury. WorkSafe NZ and civil courts take structural failures seriously.
Can You Retrospectively Consent an Unconsented Wall?
Sometimes — but it's not straightforward. You'll need to apply to your council for a Certificate of Acceptance (CoA). This is a process where the council inspects the completed work and determines whether it meets the Building Code. The challenges include:
- The council may require parts of the wall to be exposed for inspection
- You'll likely need engineering sign-off from a geotechnical or structural engineer
- There's no guarantee the council will issue a CoA — if the wall doesn't meet code, you may still have to remove or rebuild it
- Fees apply, and the process can take time
For technical guidance on what the Building Code requires for retaining structures, refer to BRANZ.
What About Walls Built by a Previous Owner?
If you've purchased a property with an unconsented retaining wall, the problem becomes yours. This is why it's critical to check the LIM report and ask your solicitor about any unconsented structures before you buy. If you've already purchased and discovered the issue, speak to your council early — proactive engagement is always better than waiting for enforcement.
Retaining Walls and Licensed Building Practitioners
For walls that require consent, the design and construction must meet the NZ Building Code — particularly clauses relating to structural stability and drainage. Walls over a certain height or complexity will require input from a licensed engineer. The builder carrying out the work should ideally be a Licensed Building Practitioner (LBP), which gives you legal protection and ensures the work is done to a recognised standard.
When to Call a Professional
If you're unsure whether your existing or planned retaining wall requires consent, don't guess. Contact:
- Your local council — for consent requirements and district plan rules
- A Licensed Building Practitioner — for compliant construction
- A geotechnical or structural engineer — for walls on difficult ground or over 1.5 m
- A qualified retaining wall builder — you can find local professionals on tradedirectory.co.nz
Getting it right from the start is always cheaper than fixing it later.
Licensed Building Practitioner (LBP)
