How much does a prefab granny flat cost in New Zealand?

Granny flats are one of the easiest ways to add more liveable space to your property. Their versatility allows you to rent them out, comfortably house guests or create a dedicated home office.

The best bit? However you use one, you’ve already added value to your property. 

In previous blogs, we’ve explored why taking the prefab path is the fastest way to build a minor dwelling such as a granny flat. But how much will a project like this actually cost?

That’s what we’re diving into here. Specifically, the key factors impacting the cost of prefab granny flats, why the prefabricated approach is a cost-certain choice and what designs will work for you.

First up: the costs you need to consider

Everyone has different ideas, needs and sites to manage. So it’s worth knowing what factors impact the final cost – no matter how you choose to build. 

Because when it comes to granny flat costs, you’ll need to think about:

• Size and layout – Generally speaking, the larger your granny flat is, the more it will cost. You’ll need to consider what design works for you and your property, how much space you need and how you want it to function.
• Customisations – If you want your granny flat to be self-contained, you’ll need a kitchen, bathroom and bedrooms. How you fit and finish those is up to you – but the cost will vary depending on what you’re after.
• Site conditions – Each site is different. Factors such as steep terrain or difficult access can impact your project price.
• Council fees and consent costs – These will differ across councils. However, Advance Build manages all this for you, providing peace of mind throughout the approvals process. 

What you really want to know

The big question: how does prefab save you time (and create cost-certainty)? Read on.

One of the biggest influencers of cost is, of course, your method of building. And prefab undoubtedly gives you a significant advantage.

Why? Because, unlike traditional builds which happen solely onsite, prefabricated ones are largely done offsite in a factory. This means your project isn’t impacted by weather or other site challenges. And that means your timeframe isn’t pushed out (and your budget isn’t pushed up). 

At Advance Build, we take the time upfront to consider all the costs of a project. This detailed, transparent pricing gives you a clear understanding of the budget you need – and peace of mind that it won’t change along the way. 

​​But how do these efficiencies truly stack up? Let’s look more closely at the cost of prefab granny flats – and why they come in lower than traditional builds. 

Granny flat cost comparison: prefab vs traditional

Essentially, it comes down to these key factors:

• Project duration – Typically, prefab is a much faster way to build. At Advance Build, we take around 8 weeks to construct a granny flat in our factory – something that could take many months with a traditional approach. Those weather and onsite delays often associated with traditional builds can really put the brakes on a build! 
• Offsite construction – Taking construction offsite and into a process-driven factory speeds up building projects significantly. This approach reduces those inevitable onsite errors – and the time (and cost) of fixing them. Better yet, offsite construction also means you aren’t faced with the mess and chaos of tradespeople turning up each day. No vehicles blocking the road  – and minimal disruption to your existing dwelling onsite.
• Less changeable budgets – Unexpected costs are never welcome. But if your build takes longer than predicted (an all-too-common outcome with traditional construction), you could be faced with exactly that. Advance Build outlines your total project cost and build timeframe upfront, so you can better manage your finances – and avoid the stress of budget blowouts. 

Prefab granny flat designs to suit you

We’ve outlined why prefab is the most cost-certain way to build. But what exactly will you end up with?

Ultimately, it’s up to you! We have a wide range of floorplans to choose from – all of which are high-quality, modern and customisable. 

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. 

Not sure what you need? Speak to one of our experts.

Can I customise or upgrade my design?

Absolutely. While these changes can impact the final cost*, they also allow you to truly personalise your granny flat . Some of the most common upgraded features include:

• Kitchen – stone benchtops or upgraded appliances
• Bathroom – free-standing bath, tiled wall coverings, level entry showers or heated towel rails
• Laundry – customised cabinetry options.

Need inspiration? You can explore all our floorplans and the latest pricing here. 

*Regardless of the design you choose, your final price will depend on the size, layout, customisations, and site conditions of your build, as well as your local council’s fees. 

What about financing?

Without a doubt, 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.

Gearing up for a granny flat?

Consider a prefab one. It’s the quickest, most cost-effective way to increase your livable space – and your property’s value. 

Request a tailored quote today from an Advance Build expert.

FAQs

What’s included in the Advance Build price?

We offer a complete turn-key service for all our builds. That means your final cost includes design, planning, project management and construction. 

Typically, your overall project cost includes:

• Complete factory construction of your high-quality home – from structural elements to interior finishes like kitchens, bathrooms and floor coverings.
• Design, planning, project management throughout the build.
• Delivery to your site and connection of your home to its foundations. 

We provide a transparent breakdown upfront, so you know exactly what your investment covers. 

How do site conditions affect cost?

Each site is different, but sites that are steep or difficult to access may incur higher costs. Steep sites will probably need more earthworks and retaining walls, while remote ones may cost more in terms of delivery and logistics.

Can I customise my design?

Yes! We have a wide range of floorplans to choose from – all of which you can customise to suit your unique needs.