New nationwide exemptions make it easier to build a small, self-contained dwelling up to 70m2 without needing a building consent, as long as all exemption conditions are met. This type of dwelling is commonly called a granny flat.
Although this exemption is part of the Building Act, planning rules still apply and a resource consent may be needed depending on your site.
A granny flat is a small, self-contained home, on the same property as the main house.
It must be secondary to the main dwelling and owned together with it.
Under different legislation, it has different names:
- Building Act: Small Stand-alone Dwelling
- Resource Management Act, the National Environmental Standards for Detached Minor Residential Unit (NES-DMRU).
The NES-DMRU applies only to detached units – meaning the granny flat must be separate from the main house.
Granny Flats Exemption Guidance is available on building.govt.nz
Thinking about building a granny flat?
You may be able to build a new, single-storey, stand-alone granny flat up to 70m2 without needing a building consent if:
- The design is simple and fully meets the New Zealand Building Code.
- You notify Council before you start building and again when the work is completed.
- All work, including design, is carried out or supervised by Licensed Building professionals (LBP)
- You meet every condition of the granny-flat exemption.
Even without a building consent, all work must still comply with the New Zealand Building Code.
Granny flats may also be exempt from resource consent under the NES-DRMU if they meet the permitted activity standards.
What's not included in the exemption
The granny flats exemption does not apply to:
- existing structures such as sleepouts, garages or partially built buildings
- tiny homes on wheels or any dwelling on a moveable base
- container homes
- buildings larger than 70m2
- imported kitset or flat-pack homes that are not designed, engineered or built to meet the NZ Building Code.
Building an exempt granny flat
To use the granny flat exemption, your project must meet all the key design conditions.
Please refer to the full criteria on the MBIE website Granny Flats Exemption Guidance
Building requirements
- It must be new and built after your PIM is issued.
- Stand-alone and single-storey and intended for a single household.
- Classified as Housing: Detached Dwelling (Building Code Clause A1)
- 70m2 or smaller - this includes any internal garage.
Location on the site
- At least 2 metres from the main dwelling and all site boundaries (front, side and rear).
- Total site coverage must remain under 50% once the new granny flat is added.
Construction and performance
- Must fully meet the NZ Building code (no waivers or modifications).
- Must be built with lightweight steel or timber framing and lightweight cladding.
- Wet areas or tiled showers are not permitted.
Who can build it
- Designed and built, or supervised, by Licensed Building Practitioners (LPB).
Services and site conditions
- Must connect to public water, stormwater and wastewater systems or use a compliant on-site system if network services are not available.
- Land must not be affected by natural hazards, such as flooding, erosion or land instability.
Before you start building
Even if your granny flat qualifies for the building consent exemption, you must complete the following steps before any building work begins.
Get a Project Information Memorandum (PIM)
You must apply for and be issued a PIM before starting construction. The PIM provides key information about your site, services and planning rules.
Get approvals for service connections
Depending on your site, you may need approval for:
- Public water, stormwater and wastewater connections.
- Compliant on-site water and wastewater systems (where no network exists).
- Electricity connections and gas, if used.
- Vehicle crossing (driveway) approval if you need a new driveway or changes to an existing one.
Meet Resource Management Act (RMA) rules
Your granny flat must also meet planning rules, including the National Environmental Standards for Detached Minor Residential Units (NES-DMRU).
In some cases, a granny flat might meet the permitted activity standards under the NES-DMRU but still require a building consent, or it may meet the building exemption but still need a resource consent.
Key points:
- NES-DMRU rules override the Tairāwhiti Resource Management Plan (TRMP)
- NES-DMRU does not apply where:
- minimum site sizes are required for on-site wastewater
- natural hazard or stability concerns.
- both dwellings are connected to one on-site wastewater system
Every site is different, so it’s important to check with Council or a qualified professional to confirm whether the standards apply to your property.
After your granny flat is completed
Once construction is finished:
- Send all required documents to Council within 20 working days of completing the build.
- All LBPs must provide a Records of Work (Form 6) to both you and Council.
- Council will update your property file and LIM.
- No Code Compliance Certificate (CCC) is issued for exempt buildings.
- Enforcement action may occur if the granny flat is unsafe or non-compliant.
- If applicable, development contributions must be paid within 20 working days of completion.
- Council does not send reminders – meeting deadlines is the homeowner’s responsibility.
PIM expiry and development costs
Your PIM is valid for 2 years.
If it expires and you haven’t applied for an extension:
- your project no longer qualifies for the exemption
- you will need to apply for a Certificate of Acceptance (COA).
Any fees and development contributions will be applied according to the current Fees & Charges and Development Contribution Policy at the time you apply.
Essential guidance and further information
We strongly recommend reading the Granny Flats Exemption Guidance, it provides detailed information and step-by-step guides on planning, designing, building and completing a granny flat www.building.govt.nz
Find out more information about the National Environmental Standards for Detached Minor Residential Units 2025 - www.environment.govt.nz
Talk to our Duty Building Inspector and Duty Planner
Frequently asked questions
No. You can't build a granny flat on an empty section.
A granny flat must be a secondary building to a main house on the property. It can't be the only building on the site.
No. A DMRU must be a self contained residential unit, which means it needs its own kitchen and bathroom.
No. The exemption applies only to new, stand‑alone dwellings. Upgrading or converting an existing sleepout still requires a building consent.
Your project will not meet the exemption rules. You may need to apply for a Certificate of Acceptance (COA), and enforcement action may apply.
Yes, if it meets every exemption condition, including compliance with the Building Code, lightweight construction, correct setbacks, and LBP involvement.
However, some structures such as container homes, tiny homes on wheels and imported kitsets not designed to NZ standards - are not eligible for the exemption.
Yes, if public services are available.
If not, a compliant on-site water and wastewater system may be used instead.
It’s also important to check whether your existing pipes can handle additional flow.
No. It must be detached and stand alone.
Not if your project meets all permitted activity standards.
However, NES-DMRU does not apply in some situations. You may still need a resource consent if:
- if your land has minimum site area requirements for on site wastewater, or
- there are natural hazard hazard or stability issues on the property.
See the section above for essential information on National Environmental Standards for Detached Minor Residential Units 2025.
Possibly.
The NES-DMRU does not apply in areas where a minimum site area is required for on-site wastewater systems. If your property relies on a septic system and your site doesn't meet the minimum lot size, you may still need a resource consent.
No. You must have all service connection approvals in place first.
Development Contributions help fund the extra infrastructure needed when new dwellings are added, such as water supply, wastewater systems, parks and open spaces and roads.
If your property is in an area where Development Contributions apply, you will need to pay one when you build a granny flat.
Yes. The exemption does not restrict who can live in the unit.
Yes. Your rates will go up from the following July.
Rates include charges based on your property's value, as well as fixed charges.
A granny flat counts as a separate part of your property, so it attracts its own fixed charges, including the Uniform Annual General Charge (UAGC) and service charges, it it's connected to Council services.
You may be eligible for a rates remission