How Much Does it Cost to Build a Granny Flat? - Owner Builder Club

How Much Does it Cost to Build a Granny Flat?

How Much Does it Cost to Build a Granny Flat

Ever thought about adding a bit more space to your home? For the growing teenager, aging parent? Maybe you're wondering how much does it cost to build a granny flat?

Well, your not the only one! Many Aussies are turning their eyes towards a granny flat as being a nifty solution. It's grown hugely in popularity and becoming the go-to for those looking to extend their living space without breaking the bank. 

So, we thought it'd be great to dive into what it really costs to bring one of these bad boys to life in your backyard.

What's a Granny Flat, Anyway?

It’s a cozy, self-contained living area, right on your property.

These compact homes, also referred to as a secondary dwelling, are perfect for giving family members their own space or even serving as a neat little investment to rent out. The beauty of it? It's all about flexibility and making the most of your property.

The buzz around these miniature abodes is growing louder by the day among Australian homeowners. And why wouldn't it? They offer a brilliant blend of privacy and proximity, not to mention the potential to boost your property's value. 

Whether it's for your ageing parents, your grown-up kids craving a bit of independence, or just a clever way to generate some extra income, the reasons to jump on the bandwagon keep stacking up.

Why is a Granny Flat Called a Granny Flat?

Are you like us and wondered why a Granny Flat is called a Granny Flat 😅

Well, we did some digging around and apparently it dates back centuries ago to the concept of ‘dowager house'. The estates in England, Ireland and Scotland had separate quarters for the widow of the estate owner to live after the passing of her spouse. Not sure what the rule was if it was the husband passed first!

But apparently, the actual term Granny Flat was coined in Australia because we love and take care of our aging ‘Grannies' in a little flat out back.

Average Cost

Okay, enough of all that, let's get down to it because you're more interested in knowing, “How much is this going to set me back?” 

It's the million-dollar question (well, not quite a mill, thankfully) that's on everyone's mind. The truth is, the investment required can swing quite a bit, and it's all down to a few key factors.

First off, think about size. Location plays a big part too. And then there's the choice of materials and finishes.

So, what's the ballpark figure for setting up one of these cozy retreats in your backyard? 

Well, as a starting point, you're looking at somewhere between $50,000 to $200,000 on average. Yes, it's a broad range, but it gives you a rough idea of what to expect. 

Keep in mind, this is just the beginning of the conversation. Depending on your specific plans, the final price tag could be lower or, yes, even higher.

Key Factors Influencing the Price

The costs of adding that extra bit of space to your home is a bit like planning a road trip. There are several routes you can take, and various factors will determine how smooth your journey is. 

Let's break it down.


Ever noticed how a cup of coffee can cost more in one city than another? Well, building costs have a similar vibe. 

Depending on where you're planning to set up, prices can vary significantly. Urban areas, with their higher demand and sometimes stricter regulations, might see your budget stretching more than in rural settings. 

It's all about the postcode lottery when it comes to the cost of labour.

Size and Design

Here's where your vision starts to take shape. The size of the structure you're dreaming of will directly impact your budget – the larger the footprint, the higher the price. 

But it's not just about square metres. The complexity of your design also plays a massive role. 

A simple, modest layout? That's your ticket to keeping costs manageable. 

Opting for a more intricate design with custom features? Brace yourself for a higher quote. 

It's all about finding the right balance between your dreams and your budget.

Materials and Finishes

The choices you make here can really swing the needle on your budget metre. 

Going for premium materials and high-end finishes can transform your space into a luxe retreat but expect your expenses to climb. On the flip side, selecting more economical materials doesn't mean skimping on style. With a keen eye, you can find options that look great without leaving a gaping hole in your wallet. 

It's like choosing between a designer label and a chic, but affordable, boutique find – both can make you feel fabulous, but one is kinder to your bank account.

Legal and Permit Fees for a Granny Flat

Before the first shovel hits the ground, there's paperwork to be sorted. The cost of obtaining the necessary permits and ensuring everything is up to code can vary. It's crucial to factor in these legal and permit fees early on. 

They might not be the most exciting part of your project, but they're essential to making sure everything runs smoothly and legally. Think of it as the seatbelt of your construction journey – not the reason you bought the car, but definitely something you shouldn't overlook.

Unexpected Costs to Keep in Mind

You might think you've thought of everything, but there are always a few surprises along the way. These unexpected costs can sneak up on you, turning your well-planned budget into more of a rough estimate.

For starters, site preparation can be a bigger task than anticipated. It's not just about clearing the land; it might involve dealing with uneven terrain or removing existing structures. And then there's accessibility – ensuring that everyone can comfortably get to and from the new space might require additional pathways or modifications, especially if you're aiming for universal design standards.

These unforeseen expenses aren't there to rain on your parade but to remind you that a little flexibility goes a long way. It's all part of the journey to creating that perfect addition to your home.

Saving Money Without Cutting Corners

Now, let's talk about making your dollars stretch further without compromising on the quality of your project. It's possible to keep your budget in check while still achieving fantastic results.

First up, don't settle for the first quote you receive. Shopping around and getting multiple quotes can reveal a range of prices and options, giving you a better idea of what's reasonable and where you might find savings.

Choosing materials wisely is another smart move. Some materials offer the same look and durability as their more expensive counterparts but at a fraction of the cost. It's all about finding those hidden gems that deliver on both quality and value.

Lastly, consider energy-efficient designs from the get-go. Investing in good insulation, solar panels, or water-saving fixtures can save you a bundle in the long run. It's not just about the upfront costs; it's about how much you'll save on utility bills down the track. Plus, it's a win for the planet too!

How About Council Rules and Regulations?

Yep, it's a damn great question and one that you MUST investigate depending on which state you're planning to build.

For example, in Brisbane, the Brisbane City Council have very clear guidelines on building a secondary dwelling that you must follow if considering building a granny flat in Queensland.

Same goes for NSW, the NSW Government have specific guidelines to building a granny flat in NSW.

So please remember to check with your local Council on the specific guidelines!


It's clear that getting a handle on the budget is crucial, from the big picture down to the nitty-gritty details. Each decision along the way plays a part in shaping your project.

So, take a moment to reflect on your budget. And remember, seeking professional advice isn't just a step in the process; it's a wise investment in itself, especially of you’re an owner builder. 

Dream big but plan with care. Here's to turning those dreams into reality, one well-planned step at a time.

Here's to all the Grannies out there 🥂

Frequently Asked Questions (FAQ)

Can I add a kitchen or bathroom to my granny flat? 

Yes, you can include both a kitchen and a bathroom in your granny flat design. These amenities are essential for making the space fully functional and liveable. Make sure to plan these facilities according to local building codes and regulations to ensure compliance.

Are there restrictions on who can live in a granny flat?

In Queensland, there are no specific restrictions on who can occupy a granny flat. It can be used to house family members, such as elderly parents or adult children, or it can be rented out to generate income. However, it's important to check with local council regulations as they may have guidelines on occupancy.

How big can my granny flat be? 

The size of a granny flat can vary depending on your local council’s regulations. Generally, granny flats can be up to 80 square metres in floor area. However, it's crucial to consult with your local council or a professional builder to understand the specific limitations and requirements in your area.

Do granny flats add value to my property? 

Yes, adding a granny flat can potentially increase the value of your property. It creates an additional living space that can be used for family members or as a rental property, providing an extra income source.

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