NZ's New Granny Flat Rules: The Building Exemption Is Only Half of What You Need

Servy Team20 August 20267 min read

Two different laws changed on the same day. On 15 January 2026, the Building and Construction (Small Stand-alone Dwellings) Amendment Act 2025 made it possible to build a standalone dwelling up to 70 square metres without a building consent. On that same day, a second, separate piece of law commenced: the Resource Management (National Environmental Standards for Detached Minor Residential Units) Regulations 2025, or NES-DMRU, which sets its own 70-square-metre permitted activity standard for the resource consent side. Most of the coverage when this landed treated it as one rule: "granny flats don't need consent anymore." It's actually two rules, running on separate tracks, with different conditions, and meeting one doesn't automatically mean you've met the other.

What the building consent exemption actually covers

The Building Act side is about construction, not land use. To qualify, the dwelling has to be new, standalone, single-storey, and no more than 70 square metres in floor area, including any internal garage. It has to sit at least 2 metres from the principal dwelling and from other boundaries. Construction is restricted to lightweight steel or timber framing with lightweight roof cladding and wall cladding capped at 220kg per square metre, and the design can't include a level-entry shower with a waterproof membrane, which rules out the kind of fitted wet-area bathroom a lot of people picture when they think "self-contained." The work has to be carried out or supervised by a licensed building practitioner, who documents it on Forms 2A and 6A, with registered professionals doing the same for plumbing and drainlaying.

None of this is optional paperwork you can skip because council isn't reviewing plans upfront. Before anything starts, you still need a project information memorandum. In Auckland, that means emailing Auckland Council's dedicated granny flats team with Forms 2A and 2AA, your plans, and a non-refundable $537 base fee. Once it's built, a completion notification goes back to council. And the exemption has a clock on it: construction has to be completed within two years of getting the PIM, or the project falls back into needing a full building consent.

The second rule almost nobody mentions

Here's the part that gets left out of most explainers: passing the Building Act's conditions doesn't mean you've cleared the resource consent side. The NES-DMRU applies to what the National Planning Standards call a "minor residential unit": a self-contained unit that's ancillary to a principal dwelling and held in common ownership with it, on the same site. That definition carries a real consequence. A detached minor residential unit under this standard can't go on a vacant section, because there has to be an existing principal dwelling first. And because it has to stay in common ownership with that principal dwelling, it can't later be subdivided off and sold on its own title. If someone tells you a granny flat is now a way to create a second, separately sellable property, that's not what either law actually allows.

The NES-DMRU's own permitted activity standards, separate from anything in the Building Act, are: one detached minor residential unit per site; a maximum internal floor area of 70 square metres; building coverage capped at 50 percent in residential zones; a 2-metre setback from the principal dwelling; and boundary setbacks of 2 metres on all sides in residential zones, rising to 10 metres from the front boundary and 5 metres from side and rear boundaries in rural zones. Miss any one of those and the NES-DMRU stops applying, which means the ordinary district plan rules for a minor dwelling kick back in, and you may need a resource consent you weren't expecting.

Auckland's own minor dwelling rule doesn't disappear, it gets overridden upward

Before any of this, Auckland's Unitary Plan already had a permitted-activity pathway for a "minor dwelling," capped at 65 square metres, with its own conditions on outdoor living space, landscaped area, and site coverage. The NES-DMRU explicitly overrides a district plan standard where that standard is more restrictive: the government's own guidance gives building coverage as the example, where a district plan capping coverage below the NES-DMRU's 50 percent gets overridden by the higher national figure. The same override principle applies to a stricter floor-area or setback number. Practically, that means a detached minor residential unit meeting the NES-DMRU's other conditions in Auckland now gets the national 70-square-metre ceiling rather than the Unitary Plan's older 65-square-metre one, even though the Unitary Plan clause itself hasn't been rewritten. Regulation 9 cuts the other way too: if a district plan is more lenient than the NES-DMRU on a given standard, the more lenient local rule applies instead, but relying on that lenient local rule can knock you out of the separate Building Act exemption, since that exemption's own conditions, the fixed 70m² and 2m figures in Schedule 1A, don't move just because a council plan is more generous.

Auckland's cross-lease properties raise a specific version of this. The NES-DMRU defines "site" using the National Planning Standards' definition, and for a cross-lease that's read as the whole of the land subject to the cross lease, not each leasehold interest separately. A block cross-leased into six existing units still only gets one NES-DMRU-permitted detached minor residential unit across the whole site, unless the district plan specifically allows more. Anyone assuming their individual cross-lease flat counts as its own "site" for this purpose is working from the wrong definition, the same kind of cross-lease confusion that comes up with boundary fence disputes, where the person whose sign-off you need isn't always who it looks like.

What the resource consent side leaves alone, and what it doesn't

A few specific district and regional plan rules keep applying regardless of NES-DMRU compliance: subdivision, matters of national significance such as protected heritage or natural features, natural hazard controls like minimum floor levels in flood-prone areas, and reverse sensitivity setbacks from things like the electricity network or airport noise contours. On use, the NES-DMRU is more permissive than most people would guess: a compliant unit can be used for short-term rental through Airbnb or Bookabach, as long as that stays secondary to the site's residential use, without needing a separate resource consent for that activity. Non-residential use, like running a business out of it, is a different question and falls back to ordinary district plan rules, the same kind of home-occupation limits, capped at two non-resident workers and 20 vehicle trips a day in Auckland's residential zones, that apply to any home-based activity.

Money doesn't disappear either. Development contributions can still be charged for an exempt small standalone dwelling under the Building Act, and financial contributions can still apply under the NES-DMRU where a district plan has a rule enabling them, so "no consent" doesn't mean "no council fees." A law firm analysis of the changes flagged a further consequence for anyone buying a property later: because these structures can now exist without a consent record on file, a purchaser doing due diligence may need to check more than the usual LIM to confirm a granny flat on the section was actually built to comply, rather than assuming a lack of paperwork means nothing was ever built.

Getting it right before the framing goes up

The practical order is: confirm there's an existing principal dwelling on the site, check the NES-DMRU's setback and coverage numbers against your actual section rather than assuming Auckland's older 65m² figure still caps you, get the PIM and its $537 Auckland fee lodged before any work starts, and confirm your builder is either an LBP or working under one who'll sign the completion records. If any of those numbers don't fit, or if your council's district plan carries a more lenient local standard you're tempted to use instead, that's the point to ask a professional to check the building consent side of the exemption specifically, since the two tracks can diverge as described above. It's the same discipline that applies to any consent-exempt building work: being exempt from a consent doesn't mean the compliance obligations moved, only that council isn't checking them in advance. Servy's General Labour listings cover the build itself once the PIM and design are sorted; get that paperwork settled first, not once the slab's already poured.

Sources:

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