What Size Granny Flat Can I Build?

The decision to build a granny flat comes with a large number of additional decisions, each as important as the next. One of the most important decisions is of course the size of your granny flat. The granny flat will be in your backyard to stay so you are going to want to be happy about its size.

The size of granny flat that you are allowed to build is highly dependent on where you live. Within a state, the square metre allowance can be quite similar but certain areas will be more strict or lenient than others. In general, for most areas the maximum floor area size for a granny flat,  that can also qualify as a complying development, is between 60 sqm and 90 sqm. Often in remote areas the area allowance is greater.

So, now you wonder what size granny flat you can build in your specific area. Thes best thing to do is to walk on over to your local council office and ask them directly. Make sure to get the answer in hard copy. We also have put together a handy little list that will be helpful for the majority of cases, but as you will find out, with granny flats one size does not fit all!

Granny flat size in New South Wales

In the state of NSW residents can build a granny flat with floor space of up to 60 square metres. Granny flats of this size are considered complying developments, if all other conditions are met of course.

It is possible to build a granny flat with a floor size that is greater than 60 sqm, and for this you will need to submit a full development application. 100 sqm could be an option if your block of land allows for it, and your local council is feeling generous!

Granny flat size in Queensland

A complying granny flat must be both for the purpose of housing a member of your household, and it must be equal to or less than 80 square metres (if you live within the confines of the Brisbane city council). That is a full 20 square metres more than people living in NSW.

In Queensland, the rules are very much tied to the local councils so this figure can vary quite significantly. Again, if you would like to go above the dimensions considered as a complying development you will need to speak to the council.

Granny flat size in Victoria

Most councils in Victoria specify that the granny flat must instead be a Dependant Persons Unit that is, in fact, moveable.

Any structure that is to be greater than 10 sqm needs council approval in Victoria. You will need to check size limits with your local council.

Granny flat size in South Australia

In South Australia, the general rule for a complying development is that the floor space is less than or equal to 60 sqm or 70% of the floor space of the main dwelling, whichever is less.

There is also the requirement for adequate outdoor space for all tenants; this should be at least 100 sqm for sharing.  

Granny flat size in Tasmania

Granny flats in Tasmania are limited to 30% of the size of the main residence floor area. This can also vary between councils. It is hard to find much information as to the specific requirements for each council so best to consult them directly.

Granny flat size in the Australian Capital territory

The ACT takes the prize for the largest granny flat allowance! Granny flats in the Australian capital and its surrounds can be up to 90 sqm before requiring a full development application.

This additional space allowance could be due to the low density housing lifestyle that much of the ACT enjoys.

Granny flat size in Western Australia

In the west of the country, the largest granny flat you can build is one with 70 square metres of floor space. Again this does vary by council and the number is likely to be a bit more flexible in rural areas.

Granny flat size in the Northern Territory

The Northern Territory urban residents are limited to the lowest granny flat floor space allowance in the country. Those living in NT urban areas such as Darwin city can build a granny flat with a floor space area of only 50 square metres. If you are living in a more rural area, the local council may allow up to 80 square metres of floor space.  

Can a granny flat be two storey?

Now you know the floor size restrictions, but did you know that it can be possible to build up higher instead of wider?

Yes it is possible to build a 2 storey granny flat, though it will be more difficult to get this approved by your local council. In some areas it just might not be acceptable because of the type of land or because it could compromise the privacy of your neighbours. And you do not want to end up in a dispute with your neighbours!

Can a granny flat be attached to a House?

Although the most commonly pictured granny flat design is one tucked away in an unused backyard, a granny flat can also be attached to your main residence.

A few things to note about the attached granny flat option.

  • It can compromise the privacy of both parties. There is a shared wall after all.
  • The attached granny flat still requires a separate entrance for occupants.
  • The attached granny flat can prove more difficult to design, as it needs to compliment the main residence perfectly.
  • The costs involved for an attached granny flat are generally higher. In essence you are making a self contained extension onto your main residence.

How long does it take to build a granny flat?

It can take anything from 3 to 6 months to build a granny flat, this is not factoring the time required for council and building approval. The approval process can take anything from a few weeks to a few months for non complying developments, where a full development application is required.

If you are looking for a quick build option, that also doesn’t involve a whole lot of construction noise, you should look into purchasing a prefabricated granny flat. A prefabricated granny flat can be built in as little as 8 weeks, there is a lot of time saved when construction is done at a manufacturing facility.

Can you get a first home grant for a granny flat?

When it comes to housing affordability, the struggle for Australia’s youth is real. It is just not possible for most young couples to afford the two million dollar price tag that comes with a house located within 20km of the Sydney CBD or any of the main cities for that matter. Even if you end up 50km away the situation is still quite depressing, and then you also have a very annoying and long commute to work every weekday.

The solution for many young people could be to build a granny flat on their parents land. There have been cases where granny flat builds have been eligible for the first home owners grant. It certainly isn’t for everyone, but it is a great solution that may become more and more popular. See this Queensland example case as featured on the Domain website.

What happens if I build an unapproved granny flat?

Surprisingly, there are quite a few properties in Australia with an illegal structure or building. The result of a DIY job that didn’t receive much thought or pre-planning, or sometimes it can be a deliberate move to avoid the additional fees that come from getting approvals.

An unapproved granny flat or any unapproved house renovation/addition is deemed dangerous. In other words, it is not a good idea to build an unapproved granny flat. You won’t be able to rent it out legally, it won’t be recognised on the sale of your property, and in some cases, you may even be forced to demolish it. And that works out much more expensive than simply just seeking approval in the first place.

Related questions:

What is the minimum land size for a granny flat? The minimum land size required for a granny flat can varies between state and local councils. The required lot size is usually between 450 sqm and 700 sqm. If your block of land has less than 400 sqm available then you may have a hard time getting your granny flat approved.

The exact square metre measurement required is sometimes explicitly specified by the council and sometimes it is not. In the case that it is not specified, you will have to consult the council. It is likely to be approached on a case by case basis.

Does a granny flat add value? Yes and no. A granny flat is not likely to add value to a property that is greater than or even equal to the money put into construction and planning.

However it can bring value in another way. A granny flats value often lies in the lifestyle benefits it offers to property owners, they may use it for an office to house older relatives, young adults or even visitors.

Another value add for granny flats (in some states) is the extra rental income it can bring. It will take a while to earn back the initial investment though!

How long does it take to build a granny flat? Building a granny flat usually takes between 3 to 6 months, and you also must allow for any disruptions caused by bad weather.

If you are looking for something a bit speedier, you could opt for a prefabricated granny flat. Prefabricated granny flats can take between 8 and 10 weeks to build and are not affected by bad weather.

Just remember, this is just building time, you also need to factor in planning and approval time.

closing remarks

So there you have it, you are well informed on the size restrictions for granny flats in Australia, and a few other important considerations. When it comes to granny flat size it is also essential that you plan for and build a granny flat of a size that will suit your needs, now and into the future.

If you really want a two bedroom granny flat but your local council guidelines are limiting you, make sure to approach them. There are exceptions to the rules, and there is nothing worse than restricting your plans when you really didn’t have to. It is a similar situation with those who don’t really need that much extra space. If your local council states that you can build a granny flat of 90 sqm, but you really only want a small space, there is no reason to go big.

Plan your granny flat to be as big as you need it to be, and then make sure you get it approved or adjusted to fit the councils requirements. If you are planning a granny flat that is too big, maybe a granny flat isn’t for you after all, you may be better suited to splitting the land title and just building another house!

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