Yes, in many cases a homeowner can build a dry stone retaining wall themselves in New Zealand — but there are important rules around height, building consent, and site conditions that you must understand before you start. Getting it wrong can be costly, dangerous, and may affect your property's compliance history.
What Is a Dry Stone Retaining Wall?
A dry stone retaining wall (also called a drystack wall) is built from natural stone without mortar or concrete binding the stones together. The wall holds back soil through the weight and interlocking arrangement of the stones themselves. It's a traditional technique that, when done well, is durable, attractive, and allows natural drainage — which is actually one of its biggest advantages in NZ's varied climate.
NZ Building Consent Rules: What Height Can You Build Without Consent?
This is the most critical question. Under the NZ Building Code and the Building Act 2004, retaining walls are subject to consent requirements based on height and the conditions of your site.
As a general guide under Schedule 1 exemptions:
- A retaining wall that retains less than 1.5 metres of ground may be exempt from building consent — but only if it does not support any surcharge (e.g. a driveway, vehicle loads, or a building) and does not affect neighbouring properties or public spaces.
- If the wall retains 1.5 metres or more, or if there is any surcharge above it, a building consent is almost certainly required.
- Boundary proximity matters too — walls close to a boundary or neighbouring structures may require consent regardless of height.
Important: Schedule 1 exemptions are not automatic. Rules vary between councils and depend on your specific site. Always confirm with your local council before starting work. You can also check the guidance at MBIE Building Performance for the current Schedule 1 exemption criteria.
Is Dry Stone Suitable for Your Site?
Not every site suits a dry stone wall. Consider the following:
- Soil type: Loose, sandy, or expansive clay soils put more lateral pressure on a wall and may require engineered solutions.
- Slope and drainage: NZ's wet winters mean water management is essential. Dry stone walls naturally allow water to pass through, which is a genuine advantage — but the ground behind still needs to drain away from the wall base.
- Seismic activity: New Zealand is earthquake-prone. A poorly built dry stone wall can collapse in a significant shake. BRANZ provides guidance on building in NZ conditions.
- Surcharge loads: If a driveway, shed, or other structure sits above the wall, the extra load changes the engineering requirements significantly.
How to Build a Dry Stone Retaining Wall: Key Steps
1. Plan and Check Consent First
Measure the height of retained soil, check your site conditions, and contact your council. If consent is needed, get it before you dig.
2. Excavate and Prepare the Base
Dig a level trench at least 150–200 mm deep (deeper for taller walls). The base course of stone should sit below finished ground level for stability.
3. Lay the Base Course
Use your largest, flattest stones for the base. Set them firmly into the ground, slightly battered (leaning back into the slope) — a batter of roughly 1:6 (about 75–100 mm lean per 600 mm of height) is a common rule of thumb for dry stone walls.
4. Build Up in Courses
- Overlap joints between courses (like brickwork) so no vertical joint runs continuously up the wall.
- Use tie stones (long stones running back into the bank) every 1–1.5 metres along the wall and at regular height intervals to anchor the wall into the retained soil.
- Fill gaps with smaller stone, but avoid using soil as fill inside the wall.
5. Install Drainage
Place a layer of drainage aggregate (AP20 chip or similar) behind the wall before backfilling. This prevents hydrostatic pressure building up behind the wall — one of the most common causes of retaining wall failure.
6. Cap the Wall
Finish with flat capstones to protect the top course and give a tidy appearance.
Tools and Materials
| Item | Notes |
|---|---|
| Natural stone | Schist, basalt, granite, or locally sourced fieldstone work well |
| Drainage aggregate | AP20 chip or similar free-draining gravel |
| Geotextile fabric | Optional but recommended behind drainage layer |
| Spade, mattock, level | Basic excavation and levelling tools |
| Rubber mallet | For seating stones without cracking them |
| Safety gloves and boots | Stone is heavy — protect your hands and feet |
You can find drainage aggregate, geotextile fabric, and tools at Bunnings, Mitre 10, or PlaceMakers.
Safety Note
Stone is extremely heavy. Always lift with your legs, work with a helper for large stones, and never work beneath an unsupported bank. If the ground above the excavation looks unstable, stop and get professional advice. Check WorkSafe NZ for manual handling and excavation safety guidance.
When to Call a Professional
You should engage a qualified retaining wall builder or structural engineer if:
- The wall will retain 1.5 metres or more of soil
- There is any surcharge load (driveway, building, vehicle access) above the wall
- Your site has poor drainage, expansive soils, or a steep slope
- The wall is near a boundary, public footpath, or neighbouring structure
- You are unsure about consent requirements
- The ground is unstable or you've encountered unexpected conditions during excavation
A licensed professional can also certify the work where consent is required. You can find experienced local retaining wall builders on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
