A New Zealand residential building contract should clearly identify the scope of works, price and payment basis, variation process, defects provisions, dispute resolution, and insurance responsibilities. If any of these are missing from the contract your builder has put in front of you, do not sign it until you understand why.
- A fixed-price contract based on a detailed specification gives you the most price certainty, as long as provisional sums and prime cost items are clearly listed.
- In New Zealand, residential building work of $30,000 or more (including GST) must have a written contract under the Building Act 2004, but the legal minimum is a starting point, not a full safeguard.
A building project is too large and too personal to leave its terms unclear. Review the proposed contract to understand how it addresses these elements. This is a general contract-reading guide, not legal advice or a statement of JRA’s standard contract terms. Have a lawyer review the proposed agreement and check the current requirements before signing.
The Reality Check: The Contract Matters More Than the Quote
A price alone does not explain every obligation. The quote describes the proposed work and its pricing basis; the contract should explain what happens if scope, timing or other agreed conditions change. Read those documents together, rather than assuming that accepting a total price settles every detail.
A strong contract protects both parties. It defines the scope, sets the price, establishes the payment terms, allocates risk, and provides a pathway for resolving problems. A weak contract, or no written contract at all, leaves every disagreement open to interpretation.
For residential building work of $30,000 or more (including GST), a written contract is required. MBIE’s guidance on why contracts are valuable also explains the pre-contract checklist and disclosure information. Use the legal requirements as a starting point, then check how your actual agreement addresses the project’s risks.
Types of Building Contracts in New Zealand
What is a fixed-price contract?
The builder agrees to complete a defined scope of works for a fixed price. If the actual cost exceeds the contract price (within the agreed scope), the builder absorbs the difference. If the cost is lower, the builder keeps the margin.
The key is “defined scope”. A fixed-price contract gives a price for specified work, subject to its actual terms, allowances, exclusions and permitted adjustments. Compare the specification with the drawings and quotation. An undefined item is a question to resolve before signing, not proof it will be included at no extra cost.
At JRA, our in-house quantity surveying supports cost planning. The quotation sets out clarifications and assumptions for the proposed work; a fixed price applies to the agreed scope and contract terms.
What is a cost-plus contract?
The builder charges actual costs (materials, labour, subcontractors) plus a margin (usually a percentage or fixed fee). The homeowner pays whatever the project actually costs.
Cost-plus can make sense for complex or uncertain projects where the scope cannot be fully defined upfront (heritage restorations, earthquake strengthening, staged work). But it transfers price risk to the homeowner. There is no ceiling unless one is written in.
What is a charge-up (time and materials) arrangement?
Under a charge-up arrangement, payment is based on time and materials under the agreed terms. A scope can still be defined, but the final total may remain uncertain. Check the rates, records, purchasing responsibilities, reporting and any agreed limit before deciding whether the arrangement suits the work.
| Contract type | Who carries price risk | Best suited to | Watch out for |
|---|---|---|---|
| Fixed price | Mostly the builder, within the agreed scope | New builds and renovations with a detailed specification | Vague specifications and large provisional sums |
| Cost plus | Mostly the homeowner | Complex or uncertain scopes, such as heritage work | No agreed ceiling or reporting process |
| Charge-up | The homeowner | Small maintenance and minor works | No fixed scope or price |
Planning a building project? Skip the guesswork and book a free consultation with JRA. We can discuss your project goals, scope and next steps.
Fixed-price contracts depend on a defined scope. Contingency allows for risks, while the contract’s allowances, exclusions and variation terms explain how unknowns and changes are handled.
What Your Building Contract Should Include
1. Scope of works
The contract should identify what will be built, the specification and the relevant materials. Check the drawing revisions, finishes schedule, inclusions and exclusions together. Ambiguity can leave the parties with different expectations, so record the answer before relying on it in your budget.
A good scope includes: drawings (referenced by drawing number and revision), a written specification, a schedule of materials and finishes, and a clear statement of what is included and what is excluded. If the contract says "kitchen cabinetry" without specifying the manufacturer, material, colour, handle style and layout, the builder's interpretation may differ from yours.
2. Contract price and payment schedule
Check the contract price and how payments are calculated and scheduled. Payments may be linked to stages or another agreed basis; do not assume every fixed-price contract uses the same arrangement. If stage payments apply, define the completion evidence for each stage, such as foundations, framing, roof, fit-out or practical completion.
Compare each payment with the work, materials or other obligation it covers and the agreed verification process. Understand any deposit or advance payment separately. Paying ahead can increase your exposure if the contractor cannot finish; do not assume an invoice proves an inspection has passed.
3. Variation process
A variation is any change to the agreed scope after the contract is signed. This includes changes requested by the homeowner, changes required by council, and changes caused by unforeseen site conditions.
Check how the contract requires changes to be requested, priced and approved. Record the scope, cost and programme effect before authorising a change, using the agreed approval method. Ask how urgent work or changes that cannot be fully priced in advance are handled; do not assume every contract has the same signature procedure.
Without a written variation process, you may discover at the end of the project that the builder has added costs for work you thought was included, or that you requested without understanding the price.
4. Timeline and delays
The contract should include a construction programme with a start date, milestone dates and a practical completion date. It should also address what happens when the project is delayed.
Delays caused by the builder (under-resourcing, poor scheduling, subcontractor issues) should be the builder's responsibility. Delays caused by the homeowner (late decisions, scope changes, access restrictions) or by events outside either party's control (weather, council processing, supply chain disruptions) may entitle the builder to a time extension.
A well-drafted contract distinguishes between these categories and sets out the process for claiming and granting time extensions. It should also address whether liquidated damages apply if the builder exceeds the completion date without a valid extension.
5. Defects liability period
Read the contract’s defects provisions alongside statutory consumer protections. The contractual period and its start point should be stated, rather than inferred from a handover conversation. Do not treat the end of that period as the end of every possible obligation.
Separately, the Building Act provides a 12-month defect repair period after completion. Notify defects in writing and keep the record. MBIE explains the distinction between this protection and longer-term implied warranties; the specific facts and exceptions still matter.
A third-party guarantee is another product with its own eligibility, exclusions, limits and claim process. Naming Halo or another scheme does not establish that your project is covered. Ask for the actual project documents before relying on protection.
6. Insurance and guarantees
The contract should confirm that the builder holds public liability insurance, contract works insurance (covering the building during construction), and professional indemnity insurance if design work is included. Ask for certificates of currency, not just a statement that insurance exists.
For restricted building work, check that the people doing or supervising it hold the relevant Licensed Building Practitioner (LBP) licences. This is separate from company membership and insurance. Check any proposed third-party guarantee’s acceptance and terms for your project; neither an LBP licence nor a scheme name guarantees completion or payment of a claim.
7. Dispute resolution
Even with a good contract and good intentions, disputes can arise. The contract should set out a stepped dispute resolution process: first, direct negotiation between the parties; then mediation; then, if necessary, adjudication or arbitration.
Choose the dispute pathway for the actual issue. Contract disputes may involve negotiation, mediation, adjudication, arbitration or a court/tribunal, depending on the contract and law. MBIE determinations address specified Building Act and Building Code matters, not contractual disputes. Check the relevant procedure and get advice before assuming a pathway applies.
Provisional Sums, Prime Cost Items and Allowances
These three terms appear in most building contracts and are a common source of confusion and disputes.
Provisional sums are estimated allowances for work that cannot be accurately priced when the contract is signed. Common examples include excavation (where ground conditions are uncertain until digging starts), stormwater connections (where Council requirements may change), and remediation of existing structure (where the extent of damage is unknown until the wall is opened). A provisional sum should state clearly what it covers, what triggers an adjustment, and how the final cost is calculated. Check how the contract adjusts the allowance up or down, including any margin, supporting invoices and approval requirements. Do not assume the adjustment is simply the supplier-price difference.
Prime cost items are allowances for specific products or materials that the homeowner will select during construction: kitchen appliances, bathroom fixtures, tiles, benchtops, lighting. The contract includes an allowance per item, and the homeowner's final selection determines whether the contract price goes up, down or stays the same. Track your prime cost selections carefully. In a hypothetical example, selecting three items at $2,000 above each allowance adds $6,000 before any applicable margin or other adjustment. The contract determines how that change is recorded and approved; it is not automatically outside the variation process.
Allowances is a broader term that can refer to either provisional sums or prime cost items depending on the contract. If your contract uses the word "allowance" without further definition, ask the builder to clarify whether it is a provisional sum (scope uncertain) or a prime cost item (product selection pending). The distinction determines who carries the risk of the final cost exceeding the estimate.
Review provisional sums and prime cost items in the proposed contract: what each covers, the basis of the estimate and how any adjustment changes what you pay. JRA provides in-house quantity surveying and a quotation with clarifications and assumptions.
Payment Claims Under the Construction Contracts Act 2002
New Zealand's Construction Contracts Act 2002 governs the payment process for construction work, including residential building. Under the Act, a builder can issue a payment claim at each stage of the work. The homeowner then has a defined period to respond with a payment schedule (accepting the claim, disputing part of it, or rejecting it with reasons).
Key points homeowners should understand:
- Responding to a payment claim matters. If you do not respond to a payment claim within the time specified in the contract (or 20 working days if the contract is silent), the claim may become a "default" and the full amount may become payable. Silence is not a safe response.
- A payment schedule is your opportunity to raise issues. If the work at a particular stage is incomplete, defective, or does not match the contract, the payment schedule is where you document that. Paying in full and raising issues later is harder.
- Adjudication is available for payment disputes. If the builder and homeowner cannot agree on a payment claim, either party can refer the dispute to adjudication under the Act. An adjudicator’s determination can be enforceable even while the underlying dispute continues. The procedure, costs and any challenge depend on the matter; seek prompt advice rather than assuming it is always cheaper or faster than another route.
Review the payment schedule in your proposed contract: when claims fall due, what work each claim covers and what information is required to verify it before payment.
Practical Completion, CCC and Handover
The end of a building project has several distinct milestones that homeowners often conflate:
Practical completion is a contract-defined milestone. It often allows minor outstanding items, but the actual test and its effect depend on the agreement. Check the notification and assessment process, the incomplete-work list and any approvals required before occupation. A contractual completion notice is not a substitute for council sign-off.
Defect identification. Arrange a walk-through and record incomplete or defective items, with photographs where useful. Check who will address each item and when. Distinguish the contract’s practical-completion and defects provisions from the statutory defect repair period after completion; do not assume their dates or procedures are identical.
Code Compliance Certificate (CCC). This confirms compliance with the building consent. The owner is responsible for applying, although an authorised agent may do so. The building consent authority generally has 20 working days to decide, with time suspended for further information and extensions possible by agreement. Check who assembles the documents and whether the contract links any payment to the CCC.
Implied warranties. The Building Act implies protections into residential building contracts covering matters such as proper workmanship, suitable materials and compliance. Claims can be brought for up to 10 years after completion, subject to the applicable legal rules. This is not an automatic insurance payout or the same protection as a third-party guarantee.
| Milestone | What it means | Typical timeframe |
|---|---|---|
| Practical completion | Contractual completion milestone; minor items may remain | Defined in the contract; check occupation approvals separately |
| Contractual defects provisions | Agreed process for reporting and addressing defects | Check the contract’s period and starting event |
| Statutory defect repair period | Notify defects in writing; statutory protections apply | 12 months after completion |
| Code Compliance Certificate | Council confirms the work complies with the building consent | Generally 20 working days to decide; information requests can pause time |
| Implied warranties | Statutory protections distinct from insurance | Claims up to 10 years after completion, subject to legal rules |
Keep these milestones separate. Contractual practical completion does not by itself establish lawful occupation or that every defect is resolved. A CCC is not a defect-free certificate. For the statutory protections, see MBIE’s homeowner protection guidance and obtain advice about a particular claim.
What to check before you sign off on practical completion: Walk every room. Open every door and window. Run every tap. Flush every toilet. Turn on every light switch. Check every surface for damage, scratches or unfinished work. Take photos. Compile your defects list before you sign, not after. Before accepting a completion notice, check its contractual effect and any outstanding approvals, work or documents. Record what remains and the agreed response. Do not sign on the assumption that a handover automatically settles all obligations or starts every protection on the same date.
Typical Auckland Contract Scenarios
The two examples below are illustrative scenarios based on common Auckland situations. They are not specific JRA projects. They show how the same project can feel completely different depending on how the contract is written.
Scenario 1: The Fixed-Price Contract With a Detailed Specification
- Typical setting: A homeowner signing a fixed-price contract for a kitchen and living area renovation in an older Auckland home
- How the contract is written: Drawings referenced by number and revision, a written specification and finishes schedule, a provisional sum for subfloor repairs (because the condition is unknown until the floor is opened), clearly listed prime cost items for appliances and tapware, and payments tied to completed stages
- The Reality: In this hypothetical scenario, opening the floor reveals pile repairs covered by the provisional-sum description. The homeowner asks for the proposed repair scope, cost basis and programme effect. The contract determines how the allowance is adjusted and the change approved; the allowance is not necessarily a cost cap.
Scenario 2: The Vague Specification That Drifts
- Typical setting: The same renovation, signed on a contract where the specification says "standard finish" and several items are listed only as "allowances"
- How the contract is written: No drawing references, undefined allowances, no written variation process, and a payment schedule based on calendar dates rather than completed stages
- The Reality: Small upgrades add up quietly. In this hypothetical scenario, selections exceed their allowances and verbal changes are not recorded. The parties then disagree about the revised total and what was authorised. Nobody set out to cause a dispute. The contract simply left too much open to interpretation, which is why the checks below are worth raising before you sign.
The Red Flag Warning: What to Check Before You Sign
These are contract gaps to raise before signing. Addressing them early can help clarify responsibilities and expectations.
No written contract at all. For residential work of $30,000 or more (including GST), a written contract is a legal requirement. Do not start work on a verbal agreement.
Unclear upfront deposit. Ask what the deposit covers, when it is due and how it relates to the work, ordered materials and any guarantee conditions. Check the proposed amount with your adviser. There is no universal percentage in this guide, and an unsupported “standard deposit” is not a safe basis for payment.
Vague scope. If the specification says "standard finish" or "builder's selection" without defining what that means, you are giving the builder discretion to choose the cheapest option that technically complies.
No variation process. If the contract does not require written approval for variations, you have no control over cost changes during construction.
Payment schedule front-loaded. If the payment milestones put more money in the builder's hands than the value of work completed, you are carrying the risk. Payments should track completed work, not the builder's cash flow needs.
Unclear defects provisions. Identify the contract’s reporting process, period and start point alongside statutory protections. Keep the contractor’s contact details and written records so a defect can be raised promptly; do not assume silence in the contract removes consumer rights.
No room for independent advice. Having the contract reviewed by a lawyer or QS before signing is good practice, and a clear contract should stand up well to that review.
What JRA Does Differently
Our in-house quantity surveying supports cost planning, and our quotation sets out clarifications and assumptions. JRA offers fixed-price contracts for the agreed scope, subject to the contract terms. Review allowances, variations and payment requirements in your proposed contract.
Every project starts with an obligation-free initial contact and a site meeting. Our estimate of costs tests feasibility before detailed design, and our quotation sets out clarifications and assumptions. Contract agreements are signed only once you are happy with the final design, contract sum and timeline. During the construction phase, we discuss the cost, buildability and practicality of any change before it proceeds, and at completion we walk you through the finished project. JRA offers fixed-price contracts for the agreed scope, subject to the contract terms, and our Build with Confidence guarantee. Our how it works page explains each step.
Use an early estimate to test feasibility. Confirm the scope and quotation assumptions before treating the pricing as a contract commitment.
If you are starting a building project and want to discuss the scope and next steps, get in touch with JRA. You can also request an estimate to see how our QS-led process works, explore our guide to Auckland new build costs, read about choosing a new home builder and how builder-architect collaboration protects your project from day one. Visit the JRA Construction homepage to meet our Auckland residential building team.
Frequently Asked Questions
Do I need a written building contract in New Zealand?
Yes. The Building Act 2004 requires a written contract for residential building work of $30,000 or more (including GST). Even below that threshold, a written agreement is strongly recommended because it protects both parties if a dispute arises.
What is a provisional sum in a building contract?
A provisional sum is an estimated allowance for work that cannot be accurately priced at the time the contract is signed (e.g., excavation where ground conditions are uncertain). The actual cost is confirmed during construction and the contract price adjusts accordingly. A good contract clearly identifies each provisional sum and explains what triggers the adjustment.
How much deposit should I pay a builder?
Use the proposed contract, payment basis and any guarantee conditions to assess the deposit, not an assumed standard percentage. Ask what the payment covers and what happens if the project does not proceed. Have your adviser assess the exposure before paying; this guide does not state JRA’s deposit terms.
What happens if my builder goes into liquidation?
If your builder cannot complete the work, your remedies depend on the contract, any third-party guarantee (Master Build Guarantee, Halo, etc.), and the builder's insurance. A third-party scheme may provide specified protection only if the project was accepted and the policy conditions are met. Obtain prompt independent advice about the contract, accepted cover and recovery options; no scheme name alone establishes that a claim will be paid.
Can I make changes during construction?
Yes, but every change should be documented as a written variation with agreed cost and time impacts before the work proceeds. Keep the approval record and ensure the agreed change reaches the people carrying out the work. A verbal conversation alone can leave different understandings of what was authorised.
What is the defects liability period?
It is a contract-defined period and process for addressing defects after the agreed completion milestone. Read it alongside the Building Act’s 12-month defect repair period after completion and the longer-term implied warranties. Record defects in writing and check the applicable terms; these are different protections, not one automatic guarantee.