Do you need a building consent for a granny flat in 2026?

What the exemption covers

The rule sits in Schedule 1A of the Building Act. It applies to a small standalone dwelling that is new, single storey, self-contained, and has a floor area of 70m² or less measured inside the external walls. An attached garage counts towards the 70m². It has to be at least 2m from every legal boundary and from any other residential building, sit no more than 1m above the ground, and be no more than 4m high above the floor.

It also has to be built the ordinary way. Timber or light steel framing, a lightweight roof (20kg per square metre or less, which covers metal roofing) and wall cladding of 220kg per square metre or less, which covers weatherboard, brick veneer and most modern claddings.

What it does not cover

• Anything over 70m², or with a mezzanine or second storey.
• Converting an existing garage or sleepout. The exemption is for new buildings only.
• Tiny houses on wheels. They come under different rules.
• A level entry or wet floor shower that needs a waterproof membrane. A standard acrylic shower unit is fine.
• A wood burner or other solid fuel heater. Heating has to be electric or gas.
• A site with a natural hazard, such as flooding, erosion or slips, unless the design can properly deal with it.

Council is still involved, twice

Before work starts you apply to your council for a project information memorandum, a PIM. The PIM is not an approval and council cannot refuse the build, but work cannot legally start until it is issued. It tells you about hazards, services and any development contributions that apply. If the granny flat is built off site, the PIM is for the section it ends up on.

After the build, you have 20 working days to send council the final plans, the records of work from the licensed builders, and the electrical and gas certificates. The whole build has to be finished within two years of the PIM being issued, or you apply for an extension.

Exempt from consent is not exempt from the Building Code

This is the part most often misunderstood. The Building Code applies in full. Structure, weathertightness, insulation, fire safety, ventilation, plumbing and drainage all have to comply. Restricted building work, which covers the structure and the weatherproofing, must be done or supervised by a Licensed Building Practitioner. The homeowner is legally responsible for the work complying, which is why choosing who builds it matters more, not less, when there is no council inspector.

No code compliance certificate, so your paperwork is your proof

Because council does not inspect exempt work, it does not issue a code compliance certificate. Your evidence that the home was properly built is the document pack: final plans, records of work, certificates of work and the electrical and gas certificates. Banks and insurers ask for it, and so will a buyer when you sell. Keep it, and make sure whoever builds your granny flat hands it over complete.

Resource consent is a separate question

The building consent exemption and resource consent are two different systems. National standards now allow most detached minor dwellings without a resource consent, but district plan rules on things like coverage, height and outdoor living space still apply, and some sites will still need one. Ask your council, or ask us to check as part of a site visit.

This guide summarises MBIE's Granny Flats Exemption Guidance (December 2025). It is general information, not legal advice. Every site is different, and we confirm what applies to yours before you commit to anything.