Do I Need a Written Building Contract? The $30,000 Rule and What It Protects (NZ)

sp8002
May 31
4 min read

For residential building work of $30,000 or more, New Zealand law has required a written contract since 2015. Here is what that rule covers, the disclosure your builder must give you, and why it is the foundation under all your variation protections.

By Steve Parker · Trueworks · NZ construction contract review · 6 min

What you'll learn

The $30,000 written-contract rule and where it comes from
The disclosure and checklist your builder must give you before signing
What protects you when there is no written contract at all

Quick answer: For residential building work of $30,000 or more (including GST), New Zealand law has required a written contract since 1 January 2015, under Part 4A of the Building Act 2004. The builder must also give you prescribed disclosure information and a checklist before you sign. If there is no written contract, the implied terms — including the variation procedure and the statutory warranties — apply by law anyway, and the missing contract is the builder's breach, not your problem. The written-contract rule is the foundation under all of your variation protections.

A surprising number of NZ residential jobs over $30,000 still run on a handshake, an email, or a one-page quote. Homeowners often discover the rules only when a variation dispute starts. Here is the floor the law puts under you.

The $30,000 written-contract rule

Since 1 January 2015, under Part 4A of the Building Act 2004, a written contract has been mandatory for residential building work that costs $30,000 or more, including GST. This is not optional and it is not waivable by agreement. It exists precisely so that scope, price, and the process for changing them are written down before the work starts.

The disclosure and checklist you are owed before signing

For work at or above the threshold, the builder must also give you, before you enter the contract, prescribed disclosure information (about the company and the people doing the work, their qualifications, insurance and guarantees) and a checklist

explaining what to expect and your rights. These are not marketing documents — they are required, and a builder who skips them has not met their obligations.

The implied warranties and the defect period

Separately, the Building Act 2004 writes a set of implied warranties into all residential building work — that the work will be done properly, competently, to the plans and specifications, with suitable materials, and will comply with the Building Code. These apply whether your contract is written, oral, or silent on the point. There is also a period after completion during which you can require the builder to put right defects you notify — generally treated as 12 months for the notify-and-remedy right, with longer limitation periods behind it for more serious defects.

Why this matters for variations

The written contract is where your variation clause lives — the agreed process for how changes are requested, priced, and signed off. Where the contract is silent or there is no written contract, the implied terms

(the Building (Residential Consumer Rights and Remedies) Regulations 2014) fill the gap, including the requirement that the builder notify you in writing, within 10 working days, of a variation's effect on price, time, and consent. In other words: your right to question a variation does not depend on having a good contract. It applies either way.

Send Trueworks your contract and the line in question. You receive a written, code-cited assessment of whether it was identified, notified, and priced the way the Building Act and your contract require — a second opinion you can put straight in front of your builder. NDA available; files NZ-hosted. → Email steve@trueworks.co.nz
or start at trueworks.co.nz

Not sure a variation or charge on your build is justified?

No written contract? You are still protected

| Your situation | What applies | |---|---| | Written contract, $30,000+ | Part 4A; your contract terms; implied terms fill any gaps | | No written contract, $30,000+ | Implied terms and warranties apply by law; the missing contract is the builder's breach | | Under $30,000 | General contract law; your terms; Disputes Tribunal for disputes up to $30,000 |

The absence of a written contract weakens the builder's position, not yours. The implied variation procedure and warranties still apply, and you can still question a variation that skipped them.

FAQ — Written building contracts and the $30,000 rule

Is a written building contract really mandatory in NZ? Yes, for residential building work of $30,000 or more (including GST), since 1 January 2015 under Part 4A of the Building Act 2004.

What if my builder never gave me a written contract? The implied terms and statutory warranties apply by law regardless, and the missing contract is the builder's breach. Your variation and warranty protections still stand.

Does the $30,000 include GST? Yes — the threshold is $30,000 including GST, and it is measured across the whole project, not per invoice.

What is the checklist the builder is supposed to give me? A prescribed checklist explaining what to expect from the build and your rights, which the builder must provide before you sign for work at or above the threshold, alongside disclosure information about the business.

Do the implied warranties cover defects after I move in? Yes. There is a notify-and-remedy right for defects you raise after completion, generally treated as 12 months, with longer limitation periods sitting behind it for more serious issues.

How Trueworks helps

Trueworks checks your contract — or confirms the position where there is not one — against the Part 4A requirements and the implied terms, so you know exactly which protections apply before a variation dispute starts. You get the position in writing, with the references.

About Trueworks

Trueworks is built by Steve Parker — 20 years on the analytical side of NZ construction: variation reviews, contract advisory, and AI-augmented document analysis. It is the same defensible, code-cited read a quantity surveyor would give a variation, made available to the homeowners and trades on the receiving end of one. I answer every email personally during pilot phase.

steve@trueworks.co.nz · trueworks.co.nz