What kind of granny flat should you choose? Who should build your granny flat? How much does a granny flat cost all-up, anyway?
Granny flats are a growing market, and it’s easy to be overwhelmed by all the options available. Some builders specialise in granny flats. There are also several options for pre-built granny flats. It’s important to know which kind is best for you, and the hidden costs involved.
Here’s what you need to know about the four main kinds of granny flat on the market.
What to know before choosing a granny flat
Before you choose a granny flat, make sure you:
- Have local council approval for the type of granny flat you’re choosing.
- Know the shape of your yard suits the granny flat design.
- Get a feel for the design by visiting a show room, if possible. You want it to complement your main home and the rest of your property.
The four kinds of granny flat on the market

Granny Flat Builders
A builder specialising in granny flats has the design and construction know-how to make a quality granny flat.
Importantly, they can tailor the granny flat to your property. For example, you can choose the best window placement to take advantage of morning sunlight, get the best view of the yard, or avoid looking directly into the main home’s bathroom.
With a granny flat builder you can design your granny flat to architecturally complement your main home. This can add to property value.
Make sure you choose a builder that knows their granny flats. The following granny flat builders set the standard:
South West Granny Flat Builders | Summit Homes
Funky Little Shack – Luxury Affordable Granny Flats – Under $200k

Prefab granny flats
Prefab granny flats can be quicker and more convenient to build.
They’re constructed off-site in a factory using the same materials as a regular granny flat. The prefab granny flat is about 90 per cent built when it arrives at your yard (often by crane). Final installation, including hooking up the electrical and plumbing, can take 1-3 days.
Backyard Pods offer appealing granny flats for as little as $10, 500. Some are priced higher. Prefab granny flats are convenient and can look great, but make sure you consider the hidden costs:
- Site work fees, including grading the land where your granny flat will be and preparing the base.
- Transportation costs. This includes crane cost for final installation, which can be a few thousand dollars.
- CHP escort if your prefab granny flat is too wide for the road

“Flat pack” granny flats
Flat pack granny flats are delivered in pieces and constructed on site. They’re much easier to deliver than prefab granny flats. Extra fees still include transportation, assembly, site prep, and services connection.
As long as you consider these extra costs, Flat pack granny flats can be quite affordable. IBuild’s prices for one-bedroom flat pack granny flats range from $25 000 to $44 000 before assembly.
Want to avoid assembly costs? Many flat pack granny flats are easy to assemble yourself. YZY Kit Homes offer beautiful granny flats that are shipped from Lithouania. They come together like jigsaw puzzles, so they’re easy to DIY within four days.
They are pricier than IBuild, ranging from $60 000 – $110 700 including floor, deck, and steps.
Based in Australia, Nalla Portable Buildings is another option for DIY-assembly flat pack granny flats.

Shipping container granny flats
Shipping container granny flats are the most affordable option. They can also be transported more easily.
They’re light on construction. You’ll just be adding carpet, services, doors, room divisions and the like. You can also use multiple containers for a larger or multi-story granny flat.
Shipping containers cost around $4000. Architecture & Design estimates construction cost can range from $30,000 to $100,000.
Don’t want to DIY? A quick Google will find companies offering pre-made or customisable shipping container granny flats.
Ensure you have council approval for a shipping container granny flat on your property. You’ll also need to prepare a level base for your granny flat, like a concrete slab or low-cost decking.
Once you’ve decided what kind of granny flat is best for your needs, you can start looking at designs. The right granny flat will be an asset to your home for years to come.

Alex is a journalist and freelance writer who loves bringing you inspiring stories. Have an idea for a story? Let her know at adevylder@iinet.net.au