Getting a retaining wall built is a significant investment, and a well-written quote protects you from nasty surprises down the track. In New Zealand, retaining walls are subject to the NZ Building Code and may require a building consent, so a thorough quote should reflect that complexity — not just give you a single lump-sum figure with no detail.
A Clear Scope of Work
The quote should describe exactly what is being built: the wall type (timber, concrete block, poured concrete, gabion, or segmental retaining wall), its height and length, and the location on your property. Vague descriptions like "supply and install retaining wall" are a red flag. You want to know:
- The specific materials and product specifications (e.g. H5-treated timber, concrete block size and grade)
- How the wall will be tied back or anchored, if applicable
- Whether any existing structures, trees, or services are nearby and how they'll be managed
Building Consent and Engineering
This is one of the most important items to check. Under the NZ Building Code, retaining walls over 1.5 metres high (or lower walls that support a surcharge such as a driveway or building) generally require a building consent. Your quote should clearly state:
- Whether a consent is required and who is responsible for lodging it
- Whether a Chartered Professional Engineer (CPEng) design is needed
- The estimated consent fee (this varies by council — always confirm with your local council)
- Any geotechnical investigation costs if the ground conditions are uncertain
Always check with your local council before assuming a wall is exempt under Schedule 1 of the Building Act. You can find guidance at MBIE Building Performance.
Drainage and Waterproofing
Poor drainage is the number one cause of retaining wall failure in New Zealand. A professional quote should include:
- Subsoil drainage (ag pipe, gravel backfill, or similar) behind the wall
- Weepholes or drainage outlets through the wall face
- Any waterproofing membrane on the retained face, where appropriate
- How stormwater will be directed away from the base of the wall
If drainage isn't mentioned, ask about it directly. Leaving it out to keep the price down can cost you far more in repairs later.
Materials and Specifications
The quote should list materials with enough detail that you can compare apples with apples across multiple quotes. For example:
| Item | What to look for |
|---|---|
| Timber | H5 treatment rating for in-ground use |
| Concrete block | Compressive strength, block dimensions |
| Reinforcing steel | Bar diameter and spacing |
| Drainage aggregate | Grading specification |
| Geotextile fabric | Type and weight |
For timber products, check that the treatment meets the requirements for ground contact. BRANZ publishes useful guidance on durability and material selection.
Labour, Plant, and Site Access
Retaining wall work often involves excavation machinery, concrete trucks, or crane lifts. Your quote should cover:
- Labour costs broken down by task where possible
- Plant hire (excavator, compactor, concrete pump)
- Site access — if access is difficult, this can significantly affect cost
- Spoil removal — where does the excavated soil go, and who pays for disposal?
Timeframe and Programme
A reputable builder will give you a realistic start date and estimated completion time. Weather delays are common in New Zealand, particularly in winter, so ask how these are handled. The quote should also note any dependencies — for example, waiting on a consent approval or an engineer's sign-off before work can begin.
Warranties and Producer Statements
For consented work, your builder may need to provide a Producer Statement (PS3) confirming the work was carried out in accordance with the engineer's design. Ask whether this is included. You should also ask about:
- A workmanship warranty (typically 12 months as a minimum, though this varies)
- Any manufacturer warranties on materials
- Whether the builder holds public liability insurance and is a Licensed Building Practitioner (LBP) — this is important for restricted building work
Payment Terms
The quote should set out the payment schedule clearly — for example, a deposit on acceptance, a progress payment at a defined milestone, and a final payment on completion. Be cautious of quotes asking for large upfront payments before any work begins.
When to Call a Professional
Retaining walls that require a building consent must be designed by a qualified engineer and built by a competent tradesperson. If your wall involves restricted building work (as defined under the Building Act), it must be carried out or supervised by a Licensed Building Practitioner. Check the LBP website to verify your builder's licence. If the wall is near any underground services, contact Dial Before You Dig — this is strongly recommended before any excavation work near underground services.
For peace of mind, get at least two or three written quotes and don't automatically go with the cheapest. A quote that skips consent, drainage, or engineering may look attractive upfront but leave you liable for a wall that fails or can't be signed off.
You can find qualified retaining wall builders in your area on tradedirectory.co.nz.
Licensed Building Practitioner (LBP)
