When you’re building a home, knowing what it will cost is as important as knowing what it will look like. For years, Advance Build has delivered cost certainty with their standard residential contracts (fixed price plus provisionals) – giving homeowners confidence that the quoted price reflects the real cost of their build. Now the Advance Build team is providing absolute certainty with fixed price building contracts.

Buyers want straightforward answers to the questions: “What does a builder actually have to do before they can genuinely guarantee a fixed price?” and “What does fixed price actually mean when building in NZ?” This article has the answers and clearly explains the difference between fixed price plus provisionals and an absolute fixed price building contract and other terms like “cost-certainty”.

Fixed price plus provisionals is a type of contract where some of the work is fixed. It means the builder has accounted for all the known factors and can provide a realistic estimate of what the project should cost.

A fixed price building contract goes further: it is a legal commitment signed before construction begins, confirming the total cost of the agreed scope. The price is locked in, and the only way it changes is if the client requests a confirmed variation in writing.

Advance Build’s move to fixed price contracts formalises cost certainty as a contractual guarantee. It’s the same principle of transparency and preparation, now backed by a legally binding agreement: the price you sign for is the price you pay.

Advance Build can commit to fixed price contracts because it combines factory‑built precision with detailed upfront analysis.

Why most builders can’t truly guarantee a fixed price

Many contracts described as “fixed price” still include provisional sums – estimated allowances for parts of the project that haven’t been fully assessed. These often cover site works, foundations, drainage or service connections. The contract may look fixed, but those provisional items can still move once work begins.

This is why NZ building projects often go over budget. Common causes include:

• Unexpected ground conditions requiring deeper foundations or extra earthworks.
• Site access challenges, especially on sloping, narrow or rural sections.
• Drainage or service issues affecting wastewater, stormwater or utility connections.
• Council compliance changes, where consent conditions introduce new requirements.
• Weather delays, particularly for fully on‑site construction.
• Unpriced specification gaps, where materials or selections weren’t finalised early.

A cost‑plus contract works differently again: the client pays the actual cost of labour, materials and subcontractors, plus the builder’s margin. This offers flexibility but makes the final cost less predictable – a challenge for buyers with defined budgets or bank lending.

This is the gap Advance Build’s process is designed to close.

How Advance Build gets to a guaranteed price

Advance Build’s six‑step process is built around doing the detailed work before the contract stage:

1. Free floor plan and quote – choose an Advance Build plan, your own design, or a combination. You receive a full turn‑key proposal, so the likely cost is clear from the start.
2. Home Starter Pack – the detailed site, design and pricing analysis that makes a fixed price possible.
3. The contract – once the design and scope are finalised, the price is fixed.
4. Factory construction – built off‑site to the current NZ Building Code.
5. Delivery and site works – home delivered to the site, connected to services.
6. Handover – your new home, ready to move into.

The success of this approach is that all analysis and pricing work happens in steps one and two – before the contract is signed – which removes the uncertainty that causes variation anxiety.

The Home Starter Pack: Where the fixed price begins

The Home Starter Pack is the stage where Advance Build completes the detailed work needed to lock in a fixed price. It requires a $10,000 deposit, which is deductible from the total contract price.

It includes:

• Full site visit and levels, so access, slope and ground conditions are assessed early.
• Geotechnical report, site survey plus other site specific reports that may be required to accurately determine what site works will be required. 
• Site plan, floor plan and elevations, so the design is properly developed.
• Kitchen and electrical plans, so internal details are confirmed before pricing.
• Detailed specifications, covering materials, inclusions and finishes.
• Comprehensive pricing, based on the agreed design and scope.
• Identification of possible site challenges, factored in before the contract is agreed.
• A pencilled place for your project in Advance Build’s upcoming build schedule.

Only when the client is 100% happy with the design does Advance Build proceed to a contract, at which point the price is fixed.

This is the process that makes a genuinely fixed contract price possible: the analysis comes first, and the price is only confirmed once every variable is understood.

What is covered in an Advance Build fixed price contract?

Once both parties sign, the price is fixed for the agreed scope. The only way costs change is if the client requests a variation in writing – and that variation is confirmed and priced before any additional work proceeds.

Advance Build’s staged payment structure is:

• 5% deposit on signing (with the Home Starter Pack deposit deducted).
• 25% pre‑construction.
• 40% at lock‑up, usually around four weeks into factory construction.
• 20% before delivery, usually around eight weeks into factory construction.
• 10% on Practical Completion.

Factory construction typically takes around eight weeks, with regular updates and we welcome you to visit the factory. Delivery and site works usually take four to six weeks, depending on the level of work involved.

Here’s what the fixed price contract includes:

Fixed price vs fixed price + provisionals: What it means for you

Here’s how fixed price and standard residential (fixed price + provisionals) contracts compare across the factors that matter most when building a new home:

Neither contract type is universally better, but for most residential builds, a fixed price contract removes the uncertainty that causes financial stress.

Is a fixed price build right for you?

A fixed price contract suits buyers who want clarity, confidence and a structured process from design to handover.

This contract type is a good fit if:

• You’re a first‑time home buyer wanting a clear understanding of total cost.
• You have a defined budget and need to avoid unexpected movement.
• You need certainty for bank financing.
• You want to avoid variation anxiety once construction begins.

The trade-off is simple: design decisions must be finalised before the contract is signed. Advance Build offers a high level of design flexibility – it just happens during the planning and Home Starter Pack stages.

The process behind the promise

A fixed price contract is only as good as the analysis behind it. Advance Build can offer fixed-price contracts because of the work they do upfront: site analysis, detailed design and an honest assessment of what your build will involve – all completed before any contract is signed.

Ready to find out exactly what your new home will cost? Talk to Advance Build about the Home Starter Pack – where your fixed price begins.

Learn more at advancebuild.co.nz/process/