When Does Your Retaining Wall Need Building Consent in New Zealand?

What is a Retaining Wall?

Retaining walls are structures designed to hold back soil and stabilise sloped land. They're essential for creating level building platforms, managing stormwater runoff, and preventing erosion and landslips—especially in areas with high rainfall or seismic activity like much of New Zealand.

Pole retaining wall

Whether you're building a timber pole wall, concrete block wall, or gabion basket system, understanding when you need Building Consent or an engineered design is crucial for safety, compliance, and long-term performance.

Why Getting it Right Matters

As previously discussed in one of our other articles: Retaining Walls Are Getting Bigger , Aotearoa is a land of shifting ground and unpredictable weather. From earthquakes to atmospheric rivers, extreme conditions are increasingly common.

A correctly designed retaining wall:

• Prevents landslips and erosion

• Supports nearby buildings and infrastructure

• Redirects stormwater safely

• Protects property value and safety

Our geotechnical and structural engineering teams work together to offer a full service solution, saving you time and reducing risk

Wellington landslip - 2022

Do I Need Building Consent

Simple Answer:

You need Building Consent if:

• The wall is over 1.5 metres high, OR

• It’s within 1.5 metres of a building or boundary

These thresholds apply nationwide under the NZ Building Act.

! Over 3 metres? You'll need an engineered design, and yes we can help with that too. We now offer designs for retaining walls of most sizes, including large scale and complex sites.

What else Triggers Consent or Design?

There are additional risk factors that may require engineering input or a Resource Consent, even if the wall is under 1.5 m:

• Soft or unstable soil types

• Steep or variable ground

• Trees or large roots nearby

• Underground services

• Proximity to driveways, buildings, or swimming pools

• Site is near a stream or coastal margin
  

Even if your wall meets exemption height limits, it still must comply with the New Zealand Building Code. https://www.building.govt.nz/assets/Uploads/projects-and-consents/building-work-consent-not-required-guidance.pdf

Examples: When you Don't Need Consent

In brief, here are the plans for some common retaining wall circumstances that do not require Building Consent and engineering design:

Examples: When You Do Need Consent and an engineer

Here are the plans for some common retaining wall circumstances that do require Building Consent and engineering design:

Our Chartered Professional Engineers (CPEng) handle everything from site investigations to full design documentation, including PS1 certification for consent.

Don't Forget: Resource Consent May Also Be Needed

Even if your retaining wall passes the Building Consent test, it may still trigger a Resource Consent—especially if:

• The wall is over 2.5 m

• The site involves cutting/filling over 80m²

• It’s within a protected area or zone

• Earthworks affect stormwater flow or neighbours

Each council is different, so we recommend checking with your local authority or giving us a call. https://wellington.govt.nz/property-rates-and-building/building-and-resource-consents/resource-consents/find-out-if-you-need-a-resource-consent

Need a Retaining Wall Building Consent Designed in 2025?

Whether you’re planning a new build, fixing an old wall, or subdividing land, our team has the geotechnical and structural expertise to deliver efficient and compliant designs across New Zealand.

We offer:

• Site-specific engineered designs (including PS1s)

• Site investigations and soil testing

• Consent-ready drawings

• Liaison with councils and builders

• Construction monitoring and sign-off

Free initial chat

Not sure where to start? book a free initial consultation with one of our engineers, or call us directly. We'll help you understand what you need and what it might cost, no obligations: Book your free initial consult here