Granny Flat FAQs NZ: PIMs, Council Rules, Costs & Site Requirements
Updated: Sep 28
Thinking about building a granny flat but not sure what you can do on your property?
New Zealand's 2026 granny flat rules have made it easier to build certain small homes without a building consent. But there are still plenty of questions about council requirements, PIMs, boundaries, rural properties and what happens when a site doesn't quite meet the rules.
We've answered some of the most common questions below to help you understand what's possible, what to watch out for and where to start.
If you're new to the changes, read our guide to the new granny flat rules in New Zealand first.
Granny flat rules and council approvals
1. Do I need an existing house on my property to build a granny flat?
Not necessarily.
The 2026 building consent exemption applies to eligible new, standalone, single-storey dwellings of up to 70m². It isn't limited to properties that already have a main house.
However, your property's zoning, planning rules, access and servicing requirements still matter. Building a small home on a vacant section may be possible, but it isn't automatically permitted just because it's under 70m².
If you're considering a granny flat on vacant land, it's worth checking the property's development potential before purchasing plans.
2. Do I still need to notify council if my granny flat doesn't need building consent?
Yes.
If you're using the granny flat exemption, you must apply for and receive a Project Information Memorandum (PIM) from your council before construction starts.
You must also provide the required documentation to council once the granny flat is complete.
The exemption removes the need for a building consent on qualifying projects. It doesn't remove your responsibility to comply with the Building Code or follow the required process.
3. What is a PIM, and why do I need one?
PIM stands for Project Information Memorandum.
Think of it as a report from your council containing important information about your property and proposed building work.
It can identify matters such as natural hazards, drainage, infrastructure, heritage restrictions and relevant planning requirements.
For granny flats built under the 2026 exemption, a PIM is mandatory before construction begins.
A PIM is not a building consent. It doesn't mean council has approved your design or guaranteed that the building will comply with every requirement. That responsibility remains with the homeowner and the appropriately licensed professionals carrying out the work.
MAV Studio offers a Granny Flat Preliminary Design + PIM service to help homeowners establish an initial design and prepare for this stage.
4. What's the difference between building consent and resource consent?
These are two different things, and it's possible to need one without the other.
Building consent deals with the technical construction of a building and whether the proposed work complies with the New Zealand Building Code.
Resource consent deals with planning and environmental matters, such as how a development relates to the property's zoning and the surrounding area.
The 2026 granny flat exemption means certain dwellings can be built without building consent. Whether resource consent is required depends on the applicable planning rules and the details of your project.
For more information about the exemption, see MBIE's official granny flat guidance.
5. How do I find out what zone my property is in?
Your local council's online district plan maps are a good starting point.
These show the zoning and other planning information that may affect development on your property.
You should also check for relevant overlays and restrictions, such as flooding, coastal hazards or heritage provisions.
If you're unfamiliar with district plans, MAV Studio can help you understand the information relevant to your project through our Site Feasibility Report.
Site suitability and building requirements
6. Can I build a granny flat on rural land?
Potentially, yes.
Rural and lifestyle properties can offer plenty of space, but that doesn't necessarily make them straightforward to develop.
You may need to consider septic systems, water supply, vehicle access, ground conditions, natural hazards and the planning rules that apply to your land.
Some rural properties will suit the exemption pathway. Others may need additional approvals or a different design approach.
Before choosing a floor plan, establish what your property can accommodate.
7. Can I build multiple granny flats on my property?
Possibly, depending on your property's planning rules and available infrastructure.
However, don't assume that because one small dwelling may qualify for the building consent exemption, you can automatically build several.
Multiple dwellings can introduce additional requirements around site coverage, access, wastewater, stormwater, fire safety and planning approvals.
If you're considering several units for extended family, rental accommodation or a small retreat-style development, we recommend assessing the entire project from the outset rather than treating each building as a separate decision.
8. What is site coverage, and why does it matter?
Site coverage generally refers to the proportion of your property occupied by buildings, although the exact definition and calculation depend on the applicable planning rules.
Your existing house, garage and other buildings may already use a significant portion of the permitted coverage.
Adding a 70m² granny flat could take your property beyond the relevant limit, even if there's physically enough room for it.
That's why the size of your backyard alone isn't enough to establish whether you can build.
Wondering whether your section could accommodate a granny flat? Try our Granny Flat Site Calculator for an initial indication.
9. Can I build a granny flat close to my boundary?
It depends on the design, the relevant exemption conditions and your property's planning rules.
Boundary setbacks can affect both whether your proposed building qualifies for the exemption and whether it complies with planning requirements.
Building close to a boundary may also introduce additional fire safety and construction considerations.
Before positioning a granny flat near a fence, it's important to have the proposed layout checked against the requirements that apply to your property.
10. What if there's already a garage or shed where I want to build?
An existing building doesn't necessarily prevent you from adding a granny flat, but its position can affect your options.
You'll need to consider available space, access, site coverage and any relevant separation or fire safety requirements.
If you plan to remove the existing structure, there may also be demolition, drainage or site preparation costs to account for.
The right approach depends on the property and what you want to achieve.
11. Does my section need to be flat?
No, but a sloping section can make a granny flat more complicated and expensive to build.
Steeper sites may need additional foundation design, earthworks, retaining walls or more complex drainage solutions.
The granny flat exemption also has specific design and construction conditions, so not every foundation solution or hillside design will qualify.
A sloping site doesn't necessarily rule out a small home. It simply makes early site assessment particularly valuable.
12. What if my property is in a flood zone or another natural hazard area?
Natural hazards need to be considered before you commit to a design.
Depending on the property, these could include flooding, coastal inundation, erosion, unstable ground or other site-specific risks.
A natural hazard doesn't automatically mean you can never build, but it may affect your design, construction costs or eligibility for the exemption.
Your council's PIM will provide relevant information it holds about the site. Further specialist assessment may also be necessary.
For more complex properties, start with a Site Feasibility Report.
Design, services and costs
13. Can I design my granny flat myself?
You can develop your own ideas and floor plan, but an exempt granny flat must meet the exemption's professional design and construction requirements.
You'll need appropriately licensed professionals to carry out or supervise the relevant work.
Professional design input can also help you avoid common problems with layout, sunlight, privacy, storage and how the new dwelling relates to the existing house.
If you're looking for a starting point, explore the MAV Collection, which includes three compact architectural designs:
All designs still need to be assessed against your property's requirements and the relevant approval pathway.
14. Can I include a garage with my granny flat?
Possibly, but the garage's design, size and relationship to the dwelling can affect the applicable requirements.
The exemption is intended for certain small, standalone dwellings with simple designs. An attached garage or more complex building arrangement may mean the proposal needs to follow the standard building consent pathway.
If a garage is essential to your brief, establish the appropriate design and approval approach before purchasing plans.
15. Will I need separate power, water and wastewater connections?
Not necessarily. It depends on your existing services, the capacity available and the requirements of the relevant providers and council.
Some properties may be able to accommodate another dwelling using existing infrastructure, subject to the necessary checks and approvals.
Others may need upgraded drainage, additional wastewater capacity or new service connections.
On rural properties, water supply and septic systems can be particularly important considerations.
These costs can make a significant difference to the overall project budget, so it's worth investigating them early.
16. How much does it cost to build a granny flat in New Zealand?
There's no single figure that applies to every property.
The size and specification of the dwelling matter, but so do ground conditions, access, foundations, drainage, service connections and any necessary approvals.
A compact dwelling on a straightforward site can have a very different overall cost from the same design on a steep or difficult section.
When comparing building prices, check exactly what's included. The advertised cost of a dwelling may not include all the work needed to make it ready for occupation on your property.
Use MAV Studio's Building Cost Calculator as an initial budgeting tool, then obtain site-specific advice and construction pricing as your project progresses.
17. Will I have to pay development contributions?
You may.
Development contributions are charges councils can impose to help fund infrastructure needed to support development.
Whether they apply, and how much you'll pay, depends on the council and your project.
A building consent exemption doesn't automatically remove these charges. It's worth allowing for them in your early budget.
Future plans and next steps
18. Can I subdivide my property and sell the granny flat separately later?
Possibly, but building a granny flat and subdividing your property are two different processes.
Subdivision depends on your property's zoning, dimensions, access, servicing and other planning requirements. A dwelling qualifying for the building consent exemption doesn't guarantee that a new title can be created.
If you think you may want to subdivide in future, raise this at the beginning of the project. It could influence where you position the dwelling, how you arrange services and which design approach you choose.
Explore MAV Studio's Site Feasibility Report if subdivision is part of your longer-term plans.
19. What if my property doesn't qualify for the granny flat exemption?
That doesn't necessarily mean you can't build.
You may still be able to proceed using the standard building consent process, potentially with changes to the design or additional approvals.
For some sites, a different size, layout or location may be more practical.
The important thing is identifying the appropriate pathway before spending money on detailed plans or committing to construction.
If your property has unusual constraints or you want something designed specifically for your site, explore MAV Custom.
20. What's the best first step if I'm thinking about building a granny flat?
Start with your property, not a floor plan.
Understanding your site's opportunities and constraints early can help you choose an appropriate design, establish the likely approval pathway and develop a more realistic budget.
If you're just beginning to explore the idea, try our Granny Flat Site Calculator.
If you're considering a property with more complex constraints or wider development potential, our Site Feasibility Report can help establish what may be possible.
If you're ready to progress a granny flat design, explore our Granny Flat Preliminary Design + PIM service.
Ready to explore your granny flat options?
Whether you're planning accommodation for family, considering a rental or looking to make better use of your land, the right starting point is understanding what your property can support.
MAV Studio is a Wellington-based architectural practice working with homeowners on small homes, renovations and new builds across the country.
Explore our pre-designed home Collection, or contact MAV Studio to discuss your property and the next steps.
For a broader explanation of the legislation, read our companion article: New Granny Flat Rules NZ (2026): What You Need to Know Before You Build.
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