Most retaining wall projects in New Zealand are paid in stages rather than all upfront or all at the end. A milestone-based payment schedule protects you as the homeowner and gives your contractor confidence that cash flow will keep the job moving. Understanding how these schedules typically work — and what to watch out for — can save you stress and money.
Why a Staged Payment Schedule Makes Sense
Retaining walls can range from a simple timber sleeper wall to a complex engineered concrete block or poured concrete structure requiring a building consent. The materials, labour, and timeframes vary enormously, so a single lump-sum payment rarely suits either party. Staged payments tie money to real, visible progress, giving you checkpoints to review the work before releasing the next payment.
This approach also aligns with guidance from MBIE Building Performance, which encourages homeowners to have clear written contracts that outline payment terms before any work begins.
Typical Payment Stages for a Retaining Wall Build
While every contractor is different, a common structure for a medium-to-large retaining wall project in NZ looks something like this:
| Stage | Typical % of Total Cost | Trigger |
|---|---|---|
| Deposit / Mobilisation | 10–20% | Contract signed, materials ordered |
| Excavation & Foundation | 20–30% | Earthworks and footings complete |
| Wall Construction | 30–40% | Wall structure built to agreed height |
| Completion & Drainage | 10–20% | Backfill, drainage, tidy-up done |
| Final Retention | 5–10% | Sign-off, consent inspection passed |
These percentages are a guide only — your actual schedule will depend on the scope, materials, and what you negotiate with your builder.
The Deposit: What's Reasonable?
A deposit of 10–20% of the total contract value is standard and reasonable in the NZ trade industry. It covers the contractor's initial costs such as ordering materials, hiring machinery, and scheduling labour. Be cautious of any contractor asking for more than 30% upfront before a single sod has been turned — this is a red flag. Equally, a contractor who asks for no deposit at all may be struggling financially.
Always get a written contract that clearly states what each payment covers and what milestone must be reached before you release funds.
Progress Payments Tied to Milestones
Progress payments should be linked to specific, observable milestones — not just dates on a calendar. For example:
- Excavation and foundation payment — triggered when the ground is cut, any required engineering inspections are done, and footings are poured or compacted.
- Wall construction payment — triggered when the wall itself (whether timber, concrete block, keystone, or poured concrete) is built to the agreed height and any required council inspections at that stage are passed.
- Drainage and backfill payment — triggered when the drainage aggregate, filter cloth, and drainage pipe are installed behind the wall and backfilling is complete.
If your wall requires a building consent (generally required for walls over 1.5 metres in height, or in certain ground conditions — always confirm with your local council), there may be mandatory inspection stages set by the council that naturally align with your payment milestones.
Retentions: Holding Back a Final Payment
It is common practice to hold back a 5–10% retention until the job is fully complete and any defects are remedied. This gives you leverage if something needs fixing after the main work is done — for example, if drainage isn't performing correctly after the first rain, or if the wall face needs remedial work.
Discuss the retention amount and the conditions for releasing it clearly in your contract before work starts. Consumer NZ has useful general advice on contractor contracts and your rights as a homeowner.
Variations and Extra Costs
Retaining wall projects frequently encounter variations — unexpected rock, poor soil, or design changes. Any variation should be agreed in writing with a clear price before the extra work proceeds. Avoid verbal agreements. A good contractor will issue a variation order and get your sign-off before proceeding, and your payment schedule should be updated to reflect any changes in scope.
Consent and Engineering Costs
If your wall requires a building consent, you will also need to budget for council consent fees and potentially structural engineering fees. These are usually paid separately — engineering fees directly to the engineer, and consent fees to your local council. Confirm with your builder who is responsible for lodging the consent and how those costs are handled in the contract.
For walls that may be exempt from consent under Schedule 1 of the Building Act, always confirm with your local council before assuming no consent is needed — rules can vary by location and ground conditions. You can find general guidance at MBIE Building Performance.
Red Flags to Watch For
- Requests for more than 30% deposit upfront
- No written contract or payment schedule
- Pressure to pay the next stage before the milestone is clearly complete
- No mention of council inspections for consented work
- Vague scope of work with no itemised quote
When to Call a Professional
Retaining walls over 1.5 metres, walls on steep or unstable ground, or walls near boundaries or structures almost always require a Licensed Building Practitioner (LBP) and potentially a structural engineer. You can verify LBP status at Licensed Building Practitioners. For any wall requiring consent, restricted building work must be carried out or supervised by an LBP — this is a legal requirement under the Building Act.
Finding a qualified, experienced retaining wall builder in your area is straightforward on tradedirectory.co.nz, where you can compare local professionals and read reviews before committing.
Licensed Building Practitioner (LBP)
