Ever thought about creating more liveable space on your property? A granny flat could be the answer. 

It’s a path many New Zealanders are exploring – and for good reason. After all, these minor dwellings are an excellent way to:

• Create more living space – the perfect solution for extended family, friends and guests
• Increase your property value – without embarking on a large renovation
• Boost rental income – ideal for retirees (or anyone wanting another source of revenue)
• Provide a home office away from the main house.

But first: what exactly is a granny flat?

A granny flat is a self-contained minor dwelling. It’s separate from the main house, with its own entry. Despite its name, a granny flat isn’t just somewhere for older relatives to live. As we said above, these versatile dwellings serve a multitude of purposes!

Whatever your motivation, however, you still need to build it. And prefab is the smartest, simplest way to do it. 

We’re going to drill down into granny flats: the rules and regulations around them, how much they cost and where you can start. In particular, we’ll look at prefab granny flats, why this building approach works so well – and what this process looks like.

Can I actually build a granny flat on my property?

It’s highly likely you can, but ultimately, it depends on your council. Each one has its own rules and regulations and often differ in terms of:

• Size limits – typically, you’re allowed 60-65m², but Whangarei District Council, for example, allows 90m² (including decks)
• Zoning + land use – again, these are council-specific. But you might not get approval if your home is, say, in a commercial zone, heritage-listed or in a natural hazard area.

Do I need consents?

Yes.

You’ll need a building consent for any minor dwelling if it’s being connected to onsite services (e.g. sewer, water, power).

If you’re building a single-story detached dwelling – such as a sleepout, shed or greenhouse with no kitchen or plumbing facilities – you won’t need a building consent (in most cases). However, granny flats generally will need one because you have cooking facilities, power,  plumbing etc.

You may also require a resource consent if your project falls outside your council’s district plan – e.g. in terms of site size, coverage or proximity to boundaries.

Potential changes on their way

We recommend checking with your local council before you start planning. It’s also worth looking into the New Zealand Government’s proposed changes around granny flats. These are likely to come into force in mid-2025 and, if approved, will make it faster and easier to build minor dwellings.

Specifically, the Government wants to introduce a National Environmental Standard (NES) requiring all councils to permit granny flats on sites in rural and residential zones. This will mean homeowners can build granny flats on their property (up to 70m²) without a resource consent. However, homeowners still need to adhere to the district plan. If the district plan says 90m², you would need to get both building and resource consents, as this won’t meet the exemption rules.

Why prefab granny flats work

In short: prefabricated construction is a simple, straightforward way to build a granny flat – and many people choose it over the traditional building approach.

That’s because prefab gives you:

• A faster build – factory construction happens at the same time as site work, significantly reducing overall project duration. The efficient, streamlined building process inside our enclosed factory also speeds up construction and prevents weather delays.
• More cost certainty – and less budget blowouts
• Minimal onsite disruption – offsite construction means you only need to deal with workers on your property for site preparations and delivery + installation of your dwelling (not the entire build)
• High-quality, customisable designs – to suit your style, site and budget
• Project management – companies like Advance Build take care of the entire journey, including design, planning, consents and construction.

Prefab granny flat prices: what should I expect?

This comes down to your specific site and the style and features you choose. Essentially, your final cost depends on the:

• Size + layout of your dwelling
• Customisations you choose (e.g. kitchen + bathroom fittings)
• Site preparations – the more complex (e.g. steep or difficult access) your site is, the higher the cost
• Council fees – each council is different, so costs can vary.

Our most popular prefab granny flat designs are the Oasis 1 and the Kemp 1. The Oasis 1 is a generously-sized minor dwelling (60m²), with 2 bedrooms and plenty of living space. The Kemp 1 is a slightly smaller (47m²) 1-bedder – and a great option if you’ve got less space to work with.

The Kemp 1 starts at $216,600 and the Oasis 1 at $254,400*.

Top tip: Construction projects are less stressful when your finances are sorted. At Advance Build, we offer bridging finance to help manage your funding. You can choose from three flexible finance options – each with varying fees, deposits and payment schedules to suit your needs.

*Final prices depend on the aforementioned factors: size, layout, customisations, site conditions and council fees. 

What are my granny flat designs + options?

It can be hard to know exactly what you want and need from a granny flat. That’s why we recommend asking yourself:

• What it’s being used for
• How often you’ll use it
• How you want it to look and feel.

All our floorplans (such as Kemp 1 and Oasis 1) are modern and customisable – and built to the highest standards. Better yet, our expert team takes care of everything from start to finish, leaving you to enjoy the process.

Beyond Advance Build, companies such as Bode Homes, Tiny Home HQ and Podlife also offer a range of small granny flats.

Why Advance Build stands out

Not all companies offer project management. That means you’re responsible for coordinating everything – including approvals, site works and trades. Most of us, however, haven’t built a home before, so it can quickly become extremely stressful! We’re here to support you through everything: from the early design phase to planning, consents and construction.

Building a granny flat: where to start

Keen to get going, but feeling overwhelmed? We help make your build journey stress-free.

Our team will guide you through each step of the process – all you need to do is get in touch!

Here’s how it works

1. Floor plan + quote: Work with an Advance Build consultant to decide on your floor plan. We’ll then provide a cost estimate.
2. Home Starter Pack: Once you’ve paid the Home Starter Pack deposit of $10,000 (deductible from the total price), you’ll receive detailed concept plans. We’ll also investigate local council rules and assess the feasibility of your project.
3. Contract: After signing, we’ll finalise your design and documentation and submit drawings to council.
4. Factory construction: Your new home starts to take shape and is completed within 8 weeks. You’ll get regular updates and photos!
5. Site delivery: Your granny flat is delivered to site, installed and connected to its foundations + services. We’ll also organise council inspections and sign-off.
6. Move in: Receive your keys and start enjoying your new dwelling!

How is Advance Build different?

Thinking about building a granny flat? Talk to the Advance Build team.

The prefab approach gives you certainty around cost, timing and quality – without compromising on design.

So, if a seamless, stress-free experience sounds like you, get in touch for a free quote today.