Many retaining wall builders in New Zealand will help with — or fully manage — the building consent process, but this isn't universal. Whether consent is needed at all depends on the height and location of your wall, and whether your builder handles the paperwork is something you should confirm upfront before signing any contract.
Does Your Retaining Wall Actually Need Consent?
Not every retaining wall requires a building consent. Under Schedule 1 of the Building Act 2004, some retaining walls are exempt from consent requirements. As a general guide:
- Retaining walls up to 1.5 metres in height that do not support any surcharge (such as a driveway, vehicle load, or building) are typically exempt.
- Walls over 1.5 metres, or any wall retaining a surcharge load, will almost certainly require a building consent.
- Walls near boundaries, drainage easements, or steep slopes may have additional requirements regardless of height.
These thresholds can vary depending on your local council's rules and the specific site conditions. Always confirm with your local council before assuming your wall is exempt — the consequences of building without consent when one is required can be significant, including fines and orders to remove the structure.
For authoritative guidance on what requires consent, visit MBIE Building Performance.
What Does a Consent Application Involve?
When a building consent is required, the application typically needs to include:
- Site plans showing the wall's location relative to boundaries and structures
- Engineering drawings — for walls over a certain height or complexity, a Chartered Professional Engineer (CPEng) must design and sign off the structure
- Specifications for materials, drainage, and construction methods
- Geotechnical information if the site has challenging soils or slope stability concerns
This can be a reasonably involved process, and the cost of engineering design and council fees should be factored into your overall budget.
Will the Builder Handle It for You?
This varies widely between builders. Here's what you'll typically find:
| Builder Type | Likely Approach |
|---|---|
| Experienced retaining wall specialist | Often manages the full consent process, including liaising with engineers |
| General landscaper or fencing contractor | May build the wall but leave consent to you or refer you to an engineer |
| Licensed Building Practitioner (LBP) | Better placed to manage consent documentation; check their licence class |
The key is to ask directly before engaging anyone. A reputable builder should be upfront about what they will and won't handle. Get it in writing — your contract should clearly state who is responsible for obtaining consent.
If your builder is a Licensed Building Practitioner, they are legally able to carry out and supervise restricted building work and are generally more experienced with the consent process. For retaining walls that require consent, using an LBP is strongly advisable.
The Role of an Engineer
For walls that need consent, engineering input is almost always required. Your builder may have an engineer they work with regularly, or you may need to engage one independently. The engineer will:
- Assess the soil conditions and loads
- Design the wall structure (footing depth, reinforcing, drainage)
- Produce stamped drawings for the consent application
Don't skip this step to save money — a poorly designed retaining wall can fail catastrophically, causing property damage or injury. BRANZ has useful technical resources on retaining wall construction standards.
Drainage: A Critical Consideration
Proper drainage behind a retaining wall is essential. Hydrostatic pressure from waterlogged soil is one of the most common causes of retaining wall failure. Your consent application will need to show how drainage is addressed — typically through agricultural drain pipe, gravel backfill, and weep holes. Make sure your builder and engineer have a clear plan for this.
What to Ask Your Builder Before You Start
Before signing anything, ask your retaining wall builder:
- Do I need consent for this wall? (And can you confirm this with the council?)
- Will you manage the consent application, or is that my responsibility?
- Do you work with a structural engineer, and is their fee included in your quote?
- Are you a Licensed Building Practitioner?
- What is the expected council processing timeframe?
Getting clear answers to these questions upfront will save you stress and potential delays down the track.
When to Call a Professional
If your retaining wall is near a boundary, on a sloped site, or retaining any kind of surcharge load, or is of significant height, you should engage a qualified retaining wall builder — ideally an LBP — and a structural engineer. Don't rely on a general handyperson or landscaper for anything beyond a simple, low garden wall. The structural integrity of your property (and your neighbours') depends on getting this right.
You can find qualified retaining wall builders in your area on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
