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Prefab granny flat in New Zealand: what it costs and what the rules require
A prefab granny flat is built in a factory and set on your section, but the 70 m² granny flat exemption does not treat it differently from any other home: every condition still applies, and the PIM must be issued before any building work starts, including work in the factory. Here is what prefab means under the exemption, what a prefab granny flat costs in New Zealand and in Auckland, with prices read on sellers' websites, and what to check before you pay.
What does prefab mean under the granny flat exemption?
The exemption does not use "prefab" or "modular" as a category of home. It applies to a small stand-alone dwelling: a new, stand-alone, single-storey home of 70 m² or less, however it is built. MBIE's guidance covers off-site construction, prefabricated or modular, and says that every condition of the exemption and every licensing requirement still applies. Sellers use the two words loosely, so ask what each one means for the unit you are looking at.
The conditions that weigh most on a factory-built unit:
- Size and shape: 70 m² or less measured between the finished internal faces of the external walls once the unit is in place, single storey, no mezzanine, at least 2 m from any legal boundary and from any other residential building.
- The frame: lightweight steel or timber, or a certified composite structural building product; roof cladding of 20 kg/m² or less and wall cladding of 220 kg/m² or less.
- Services: plumbing and drainage to the set acceptable solutions, no more than 30 fixture units, no pumped systems within the dwelling, an independent source of supply for electricity, and electric or gas heaters only.
- The people: a designer, a Licensed Building Practitioner for the building work they are licensed for, a registered plumber and drainlayer, and a licensed electrician.
A prefab granny flat is not a tiny house on wheels: MBIE treats those as mobile buildings, with different requirements. Our guide to granny flat rules in New Zealand lists every condition, and our guide to expandable granny flats in New Zealand shows what each asks of a unit built overseas.
The PIM comes first, even when the unit is built in a factory
Under the Building Act as at 8 October 2026, no building work on an exempt granny flat may be carried out before the council has issued a project information memorandum (PIM) for that dwelling in relation to its final site. The Act's definition of building work includes the manufacture of a modular component, so factory work counts. One PIM is enough: a home built in a factory and moved to its final site does not need a second one.
In April 2026, the Government announced that exempt granny flats would be able to be built off-site before the PIM, with a PIM still required before any on-site work. That change is in the Building Amendment Bill, which is not law yet. Until it is, the current rule applies, so we start production only after your PIM is issued. The council has 10 working days to issue it once your application is complete, and the PIM lapses if the work is not completed within two years, unless the council allows more time.
How much is a prefab granny flat in New Zealand?
The cost of a granny flat in NZ is not the price of the building. Here are two published prices for a two-bedroom granny flat of 50 m², which we read on sellers' websites on 3 November 2026:
| Offer | Price shown | What it covers, as published |
|---|---|---|
| Seller of factory-built homes, 50 m² | $167,500, GST included | The home: kitchen, bathroom, double glazing, full insulation and cladding. Design and compliance, delivery, foundations, decking and service connections come on top, and the seller says they in most cases add 65% to 100%. For its 30 m² one-bedroom home at $109,900, it gives a total of $181,000 to $220,000, GST included. The PIM is still needed before work begins |
| Seller of units assembled on your section, 50 m² | From $204,990, GST included | Delivered, built and connected in Auckland on a flat site with normal access, with the PIM and paperwork. Sloping or hard-access sites and other regions are quoted separately, and the council's charges are checked for each address |
These two prices cannot be compared as they stand: one is the price of the home, the other covers delivery, building and connection in Auckland. Ask each seller what its total includes, then compare totals for the same items.
In Auckland, these council and Watercare charges apply whichever home you buy, though a seller may include some of them in its price. Auckland Council's base fee for a PIM for a non-consented small stand-alone dwelling is $537, GST included, and the council assesses granny flats for development contributions, which depend on your address. Watercare's infrastructure growth charge from 1 July 2026 is $29,348.46 including GST per residential unit in the metropolitan area, and its policy charges two thirds of that for a unit of 65 m² or less of gross floor area. Our guide to granny flat costs in Auckland shows every line.
Our two units, on a standard metro Auckland section, GST included: the Yard 37, two bedrooms in 35.2 m² inside the walls, is turnkey from NZD 170,000, and the Yard 57, two bedrooms and a separate living room in about 54.3 m² inside the walls, is turnkey from NZD 230,000. Each price adds up four parts, each paid to the party that charges it. We invoice only the unit, delivered to your section.
Yard 37
| The Yard 37, delivered to your section by truck and craneinvoiced by us | NZD 76,900 |
|---|---|
| GST and import chargespaid by you at the border, as the importer | aboutNZD 12,200 |
| Council and Watercare charges, typical Auckland suburbPIM, development contributions and Watercare growth charge, paid by you directly | aboutNZD 32,200 |
| Design, foundations, anchorage, expansion and connectionsby the designer, Licensed Building Practitioner and licensed trades named in your quote, under their own contracts with you | aboutNZD 48,700 |
| Turnkey price, GST included | NZD 170,000 |
Yard 57
| The Yard 57, delivered to your section by truck and craneinvoiced by us | NZD 120,400 |
|---|---|
| GST and import chargespaid by you at the border, as the importer | aboutNZD 18,500 |
| Council and Watercare charges, typical Auckland suburbPIM, development contributions and Watercare growth charge, paid by you directly | aboutNZD 32,200 |
| Design, foundations, anchorage, expansion and connectionsby the designer, Licensed Building Practitioner and licensed trades named in your quote, under their own contracts with you | aboutNZD 58,900 |
| Turnkey price, GST included | NZD 230,000 |
What to check before you buy a prefab granny flat
- Your PIM, issued before any production starts, and the planning rules for your site: see our guides to minor dwellings in Auckland and to the Single House Zone.
- Your consent pathway: the exemption, or a building consent, confirmed in writing.
- The frame, and the cladding weights, assessed by your designer against the exemption's conditions.
- The floor area inside the walls once the unit is in place, and the 2 m distances on your section.
- The plumbing layout: fixture units, connection points, no pumps within the dwelling; an independent electricity supply.
- If the unit is made overseas: the electrical documents, with the record of assessment from a New Zealand electrical inspector before connection, asbestos test reports from an accredited laboratory, and the H1 insulation specification.
- The designer, Licensed Building Practitioner, plumber, drainlayer and electrician named in the quote: check their licences on the public registers.
- A written quote that lists what is included: delivery, crane, foundations, connections, GST and import charges, the PIM fee, development contributions and Watercare's charge.
Where we stand on the exemption
Two questions about our units have been open with MBIE since 23 October 2026: whether a home built overseas can use the exemption, and whether the bolted steel frame of our units counts as a lightweight steel frame. Until MBIE answers in writing, we take no deposit for a project that relies on the exemption. Nothing is payable to us until your PIM is issued and your consent pathway is confirmed in writing. If you do not want to wait, your project can go through a building consent instead: your quote then shows the consent fees and the extra time.
PIM first, then, for a first order of a model, four to six months from order to delivery: three to six weeks of approvals, five to seven weeks of production, then shipping, customs and biosecurity clearance, and the site works by the Licensed Building Practitioner and trades named in your quote.
Frequently asked questions
Is a prefab granny flat the same as a modular granny flat?
Sellers use both words loosely, and the exemption does not depend on the word. What counts is whether the home meets every condition of the exemption: new, stand-alone, single storey, 70 m² or less inside the walls, with the frame, services and distances the Building Act requires.
Do I need a building consent for a prefab granny flat?
Not if every condition of the exemption is met and the council has issued your PIM before any building work starts. If one is not met, a building consent is needed. Resource consent is a separate question: see our guide to minor dwellings in Auckland. For our units, two questions are open with MBIE, and we take no deposit for a project that relies on the exemption until it answers in writing.
Can the factory build my prefab granny flat before my PIM is issued?
Not under the Building Act as at 8 October 2026: no building work may be carried out before the PIM, and building work includes the manufacture of a modular component. The Building Amendment Bill would change that for eligible off-site-built granny flats, but it is not law yet.
How much is a prefab granny flat in Auckland?
It depends on what the price covers. Our turnkey prices on a standard metro Auckland section, GST included, are from NZD 170,000 for a Yard 37 and from NZD 230,000 for a Yard 57. Published prices for other prefab granny flats are often the price of the home alone: ask what is included.
How long does a prefab granny flat take?
PIM first: the council has 10 working days to issue it once your application is complete. Then, for our units and for a first order of a model, allow four to six months from order to delivery, followed by the site works.
Can I put a prefab granny flat on any section in Auckland?
Only on a section with a principal home, with room for the 2 m distances, and where the planning rules allow it: the national planning standard allows one detached minor residential unit per site, and the Unitary Plan's zone rules still apply to the rest. Our guide to the Single House Zone in Auckland shows how one zone treats it.
General information, based on official sources and published prices read on 3 November 2026. It does not replace advice from your designer, your council or a lawyer. Prices and rules change: check the current version before you commit.