Yes — many retaining wall builders in New Zealand do handle earthworks and excavation as part of a complete package. In fact, the two trades are closely linked: you can't build a proper retaining wall without first preparing the ground. That said, the scope of work varies between contractors, so it pays to ask the right questions before signing anything.
Why Earthworks and Retaining Walls Go Hand in Hand
A retaining wall is only as good as the ground it sits on. Before any wall goes up, the site usually needs to be cut, levelled, or benched to create a stable base. This involves excavation — removing soil, rock, or fill — and sometimes bulk earthworks to reshape the land. Because these tasks happen in sequence, many retaining wall specialists invest in excavators, bobcats, and compaction equipment so they can manage the whole job themselves.
Hiring one contractor for both stages can save you time, money, and the headache of coordinating multiple trades on site.
What Earthworks Typically Involve
When a retaining wall builder takes on earthworks, you can generally expect:
- Site clearing — removing vegetation, topsoil, and debris
- Cut and fill — excavating higher ground and using that material to build up lower areas
- Benching — cutting stepped platforms into a slope to create level building areas
- Subgrade preparation — compacting the base to the required bearing capacity
- Drainage installation — laying ag-pipe, gravel backfill, and outlet points behind the wall
- Spoil removal — carting away excess soil if it can't be used on site
Drainage is particularly important in New Zealand's wet climate. Poor drainage behind a retaining wall is one of the most common causes of wall failure, so make sure your contractor has a clear plan for managing groundwater.
Not All Retaining Wall Builders Are the Same
Some operators are primarily concreters or blocklayers who subcontract excavation to a digger operator. Others run a full earthmoving business and build retaining walls as an extension of that. Neither approach is wrong, but you should clarify upfront:
- Do they own or hire their excavation equipment?
- Will they manage subcontractors, or do you need to arrange them separately?
- Do they have experience with the specific wall type you need (timber, concrete block, poured concrete, gabion, or segmental retaining wall systems)?
- Can they handle the drainage design and installation?
Asking for references and photos of completed projects — including the earthworks phase — is always a good idea.
Building Consent and NZ Regulations
This is where things get important. In New Zealand, retaining walls and associated earthworks are governed by the NZ Building Code and may require a building consent from your local council.
As a general guide (always confirm with your council):
| Wall Height | Likely Consent Requirement |
|---|---|
| Up to 1.5 m (no surcharge) | Often exempt under Schedule 1 of the Building Act — confirm with council |
| Over 1.5 m, or near a boundary/structure | Building consent likely required |
| Significant earthworks (large volumes) | May also trigger resource consent under the RMA |
Surcharge means any load near the top of the wall — a driveway, vehicle, building, or even a fence can count. If there's surcharge, the consent threshold may be lower.
For walls requiring consent, the design may need to be prepared or reviewed by a Chartered Professional Engineer (CPEng). A good retaining wall contractor will tell you upfront whether consent is needed and can often help you navigate the process. You can find more guidance at MBIE Building Performance.
For technical guidance on construction standards, BRANZ is an excellent NZ resource.
Earthworks and Resource Consent
Large-scale earthworks — particularly those involving significant volumes of soil, proximity to waterways, or steep slopes — may require a resource consent under the Resource Management Act (RMA), separate from any building consent. Rules vary by district, so check with your local council's planning team early in the process.
Health, Safety, and Geotechnical Risks
Excavation is one of the higher-risk activities on any residential site. Under the Health and Safety at Work Act 2015, contractors have a duty to manage risks like trench collapse, underground services, and unstable slopes. WorkSafe NZ sets out the requirements for safe excavation work.
Before any digging starts, your contractor should:
- Locate underground services (call Before U Dig — 0800 248 344)
- Assess slope stability, especially on clay-heavy or fill sites
- Have a plan for managing water during and after excavation
On challenging sites — steep terrain, expansive clay soils, or areas with a history of instability — a geotechnical engineer may need to assess the ground conditions before work begins.
When to Call a Professional
Always use a qualified, experienced contractor for retaining wall and earthworks projects. For walls over 1.5 m, near boundaries, or on difficult ground, you'll want someone who can demonstrate relevant experience and, where required, work alongside a licensed engineer.
If your project requires building consent, the work may need to be carried out or supervised by a Licensed Building Practitioner (LBP). Check your contractor's LBP registration if consent is involved.
You can find qualified local retaining wall builders and earthworks contractors on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
