Excavation work on your property may or may not require a resource consent — it depends on where you live, what your local district plan says, and the nature and scale of the work. In many cases, small-scale earthworks are permitted without consent, but larger or more sensitive projects will need approval. Here's what you need to know before you break ground.
What Is Resource Consent and Why Does It Apply to Excavation?
Resource consent is approval granted under the Resource Management Act 1991 (RMA) by your local council. It's separate from a building consent (which is governed by the Building Act 2004 and the NZ Building Code). Excavation can trigger either or both, depending on the situation.
Resource consent for earthworks is typically required when your digging, cutting, or filling activity could affect:
- The natural character of the land
- Stormwater runoff and water quality
- Neighbouring properties (e.g. through land instability or sediment)
- Significant trees, heritage sites, or ecological areas
- Coastal, wetland, or flood-prone environments
Your District Plan Sets the Rules
Every council in New Zealand has a district plan (or unitary plan, in Auckland) that sets out what earthworks are permitted as of right and what requires consent. The rules vary significantly from region to region and even zone to zone within the same council area.
Common thresholds that trigger a resource consent include:
- Earthworks exceeding a certain volume (e.g. 50 m³ or 250 m³ depending on the zone)
- Cuts or fills exceeding a certain depth or height (e.g. more than 1.5 m)
- Work within a set distance of a boundary, waterway, or slope
- Sites in special character, rural, or hazard overlay zones
Because these thresholds differ between councils, you must check your own council's district plan or contact your council's duty planner before starting any significant earthworks. Don't rely on what a neighbour did — their site or zone may have different rules.
Building Consent and the NZ Building Code
Separate from resource consent, some excavation work also requires a building consent under the Building Act. For example, if your excavation is associated with a retaining wall over 1.5 m in height (or any retaining wall that could affect neighbouring property), a building consent is likely required. Retaining walls under 1.5 m that retain no surcharge may qualify as Schedule 1 exempt work — but always confirm this with your council before proceeding.
The MBIE Building Performance website has detailed guidance on when building consent is and isn't required for earthworks and retaining structures.
When Earthworks Are Usually Permitted Without Consent
In many residential zones, minor earthworks for garden landscaping, small trenches for services, or shallow foundation preparation are permitted activities that don't need resource consent. As a rough guide, work that:
- Involves small volumes (often under 50 m³)
- Stays well clear of boundaries and waterways
- Doesn't create significant cut or fill faces
- Is on a stable, flat-to-gentle slope
…is often permitted. But again, check your district plan first.
Sensitive Sites That Almost Always Need Consent
Some sites carry overlays or designations that mean even modest earthworks need resource consent. These include:
- Coastal and esplanade areas — subject to the New Zealand Coastal Policy Statement
- Flood plains and overland flow paths
- Steep or erosion-prone land (often defined as slopes over 15–20 degrees)
- Sites with significant trees or notable vegetation
- Heritage or archaeological sites — disturbing an archaeological site without authority from Heritage New Zealand is illegal under the Heritage New Zealand Pouhere Taonga Act 2014
- Contaminated land — check the council's Listed Land Use Register (LLUR)
Sediment and Erosion Control
Even when resource consent isn't required, you may still have obligations under the RMA to prevent sediment runoff into stormwater drains or waterways. Your regional council (not just your district council) may have rules about erosion and sediment control during earthworks. BRANZ provides useful technical guidance on managing earthworks on construction sites.
Health and Safety on Excavation Sites
Regardless of consent requirements, excavation carries serious safety risks. Trenches and excavations can collapse without warning. Under the Health and Safety at Work Act 2015, anyone carrying out excavation work must manage the risks of:
- Trench collapse and engulfment
- Underground services (gas, water, electrical, telecommunications)
- Unstable batters and spoil placement
Always call Before U Dig (0800 248 344) to locate underground services before any digging. WorkSafe NZ has specific guidance on excavation safety that applies to both professionals and homeowners.
When to Call a Professional
For anything beyond very minor hand-digging, it's strongly advisable to engage a qualified excavation contractor. A professional excavator will:
- Know the local consent requirements and can help you identify what approvals are needed
- Operate machinery safely and efficiently
- Manage sediment and erosion control
- Identify and avoid underground services
If your project involves retaining walls, drainage, or structural foundations, you may also need input from a geotechnical engineer or a Licensed Building Practitioner (LBP). You can find qualified local excavation contractors on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
