Building Amendment Bill: What Mandatory Home Warranties Would Mean for Builders

The Building Amendment Bill would make a home warranty compulsory on every new house built with a consent, and on renovations of $100,000 or more that involve restricted building work. It would also end the rule that lets a homeowner recover the whole cost of a defect from whichever party can pay. None of this is law yet. The bill is still at select committee, and its timetable now depends on the Parliament elected on 7 November.

The bill amends the Building Act 2004, the main law on building work and consents, which the Ministry of Business, Innovation and Employment (MBIE) administers. Then-Minister for Building and Construction Chris Penk introduced it at the end of June 2026, and Simon Watts, the current minister, is now in charge of it. It went to Parliament’s Transport and Infrastructure Committee after its first reading in early July.

Where the bill stands before the election

Parliament dissolved on 1 October for the general election, according to the Electoral Commission’s timetable. Under section 20 of the Constitution Act 1986, business before the House lapses on dissolution, but the next Parliament can reinstate it. The committee’s own page says it is still accepting submissions and that they “will close early in the 55th Parliament”. So there’s no closing date yet, and an earlier date of 15 November no longer applies.

Everything below describes the bill as introduced (Bill 332-1). A select committee can change a bill, and regulations would fill in many details later.

Which jobs would need a home warranty

The warranty rule sits in a proposed new section 393S. It applies only to residential projects that involve restricted building work needing a building consent. Restricted building work is the work on a home’s primary structure or weathertightness that only a Licensed Building Practitioner can do or supervise, under section 84 of the Building Act. Within that, the bill would require a warranty for:

• any new house, or new apartment building under 10 metres high, at any value;
• renovations to an existing house or low-rise apartment building where the estimated value is $100,000 or more, including GST.

The warranty would have to cover all defects for at least one year, and structural defects for at least ten. It would have to come from a provider registered with MBIE, and pass to the next owner if the house is sold. There’s no opt-out for the homeowner. Commercial work, mixed-use buildings and buildings 10 metres or higher would sit outside the rule.

The bill doesn’t say in so many words that the builder must buy the warranty. Instead, it uses the consent. If the council doesn’t have enough evidence of a warranty, it must issue a certificate stopping the work, or limiting it. Carrying out building work in breach of that certificate would be an offence, with fines of up to $50,000 for an individual and $150,000 for a company. MBIE’s impact statement describes the lead builder making sure the homeowner has access to a warranty product, and the homeowner shopping around for one.

Two renovations on either side of the line

Take two $120,000 jobs, both described here for illustration. In the first, you take out a load-bearing wall between the kitchen and living room and add a new window. That’s structural and weathertightness work, so it is restricted building work and needs a consent. At $120,000 it is over the threshold, so under the bill the job couldn’t go ahead until a warranty was in place.

The second is a high-end kitchen and bathroom refit with no structural or cladding work and no consent. It costs the same, but it falls outside the warranty rule, because the trigger needs restricted building work that requires a consent. The value of a job alone wouldn’t decide it.

What would it add to the quote? MBIE’s regulatory impact statement estimated premiums for a typical $500,000 build at about $1,250 for a guarantee product and about $2,750 for an insurance-backed warranty. Those are official estimates from October 2025, not prices you can quote today. The same document found that only around 46% of new builds currently have a warranty, with lower uptake on renovations.

Proportionate liability: paying for your share

Today, liability for building defects is joint and several. A homeowner can recover the full cost from any party that is liable, regardless of how much of the defect was theirs.

The bill would replace that with proportionate liability. A court or adjudicator would limit each defendant to the share of the loss that reflects their responsibility. The bill’s own example splits a $100,000 roof defect 70% to the head contractor, 20% to the roofing subcontractor and 10% to the council. It would cover builders, subcontractors, designers and councils, in court, arbitration and adjudication under the Construction Contracts Act. It wouldn’t apply to settlements reached by negotiation or mediation.

The other side is that a homeowner couldn’t recover an insolvent party’s share from the rest. The warranty is there to fill that gap. For a builder, the bill also has a contract rule. On restricted building work on a house or low-rise apartment building, any clause that excludes or limits your liability for defective work would have no effect.

Designers, consents and PIMs

Design consultants working on projects worth $100,000 or more, including GST, would need professional indemnity insurance. Regulations would define who counts as a design consultant, so design-and-build firms will need to watch those.

Three consent changes would affect most builders sooner. Councils would have to issue a project information memorandum (PIM) within 10 working days instead of 20. Eligible solar and sustainable homes would get a 10-working-day consent. And builders could start off-site small dwellings before the PIM, which ties in with the granny flat exemption that took effect earlier this year.

When it would start

The PIM change would apply from the day after Royal assent. Warranties, designers’ insurance and proportionate liability would start on the first anniversary of Royal assent. Proportionate liability would then cover work consented on or after that day, or started after it where no consent is needed. Because the bill hasn’t had its second reading, there’s no date to plan around yet.

Until then, today’s rules stand. The implied warranties in section 362I of the Building Act apply to every residential building contract. Homeowners can still ask you to fix defects notified within 12 months of completion, and the 10-year longstop on claims still applies. Those obligations already sit in your price, alongside costs such as your ACC levies.

How to make a submission

If the bill would change how you work, the select committee wants to hear it. You can submit online through the Building Amendment Bill’s page under “Make a submission” on the Parliament website, in English or Māori. Parliament’s guide to making a submission explains the process. You only need to give your name or business name. Submissions are published and can be released at any time, so keep contact details out of the text. Tick the box if you’d like to speak to the committee in person or by video.

Be specific. Tell the committee about a job like the two above, and which side of the line it would fall. Say whether you could get a warranty, and what the clause ban would change in your contracts.

What is still undecided

A lot. The bill needs reinstating after the election, and the committee still has to report on it. Regulations would set when the one-year and ten-year periods start, what “adequate” cover means, how a renovation’s value is calculated and which work is excluded. Nobody has drafted those regulations yet. Until they are, the best preparation is to know which of your current jobs would sit over the line, and to watch for the new submission date. More regulation guides for Kiwi builders are in our New Zealand licensing and regulations section.