Under New Zealand's Building Act, a building consent is generally required for retaining walls over 1.5 m high, and for walls of any height that carry extra load or surcharge — such as a driveway, structure or slope above them. Walls under 1.5 m with no surcharge are often exempt from consent. That said, exemptions come with conditions and every site is different, so you should always confirm your specific situation with Auckland Council before you start.
Please note this article is general information only. It is not legal or engineering advice. For your project, check with Auckland Council and, where needed, a chartered professional engineer (CPEng) or a Licensed Building Practitioner, because the rules depend on the details of your site.
When does a retaining wall need consent?
A building consent is typically required in these situations:
- The wall is over 1.5 m high. Height is usually measured as the amount of ground the wall retains, and once it passes 1.5 m a consent is generally needed.
- The wall carries a surcharge — at any height. If there is extra load above or behind the wall (a driveway, building, deck footing, pool or a slope), consent is generally required even for a low wall.
- The wall is close to a boundary, building or watercourse. Proximity to structures, property boundaries or water can change what is required and often triggers consent.
- The wall is part of a larger consented project. If the wall forms part of a wider development or subdivision, it will usually be covered by that project's consent.
These are the common triggers, not a complete list. When in doubt, treat consent as likely and confirm with the council.
When might a retaining wall be exempt?
A retaining wall may fall under a building consent exemption when all of the following broadly apply:
- It is 1.5 m or less in height.
- It carries no surcharge — nothing extra loading the ground above or behind it.
- It meets the other conditions attached to the exemption.
Even where a wall is exempt from building consent, other rules can still apply — for example resource consent, rules about earthworks, or requirements near boundaries and overland flow paths. An exemption from one type of consent does not mean no rules apply, so it is always worth a quick check with Auckland Council.
What does "surcharge" actually mean?
In plain English, a surcharge is any extra weight pressing on the ground your wall is holding back, on top of the soil itself. Picture the difference between a wall with just a grassy bank behind it, and a wall with a driveway and parked cars sitting above it — the second one has to resist far greater forces.
Common surcharges include a driveway or vehicles, a building, shed or deck footing, a swimming pool, a steep slope, or another structure nearby. Because a surcharge increases the load so significantly, a wall carrying one generally needs consent regardless of how tall it is.
Consent likely? A quick summary
The table below is a general guide only — your council is the authority on your specific site.
| Situation | Consent likely? |
|---|---|
| Wall over 1.5 m high | Yes — generally required |
| Any height, carrying a surcharge (driveway, structure, slope) | Yes — generally required |
| Wall close to a boundary, building or watercourse | Likely — check with council |
| Part of a larger consented project | Covered by that project's consent |
| Under 1.5 m, no surcharge, meeting conditions | Often exempt — confirm the conditions |
What are the risks of skipping consent?
Building a wall that needed consent without getting one leaves you with unauthorised building work. That can mean enforcement action from the council, trouble when you come to sell (it appears in a LIM and during due diligence), insurance complications, and the expense of a certificate of acceptance or removing the wall altogether. And if an under-designed wall fails, the cost and liability can be far greater than the consent would ever have been. Getting it right from the start is almost always cheaper.
Why engineering and drainage matter regardless of consent
Consent is a legal requirement, but it is not what keeps a wall standing — good design and drainage are. Water building up behind a wall is one of the most common reasons walls lean, crack or collapse, so proper drainage, backfill and, where needed, engineered footings and reinforcement are essential on any wall. Even a small exempt wall benefits from being built properly. For anything that carries load or exceeds 1.5 m, engineering input from a CPEng is strongly recommended.
How we can help
We build retaining walls across Auckland and can guide you through the whole process. That includes assessing your site to work out whether consent is likely to be needed, coordinating engineering and drainage design where it is required, and building the wall compliantly to the approved plans. If you would like a hand working out where your project stands, contact us or call 09 886 7171 for a no-obligation chat.