How Big Can A Granny Flat Be?

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Granny flats, or secondary dwellings, can allow homeowners to keep parents or adult children close by giving them their own space. They can also be a great way to generate rental income.

But before you book in your builder, there are a few questions you’ll need to ask and some research to undertake to make your project a successful one.

Different councils have different requirements for residents wanting to build or renovate on their block of land. Before constructing your granny flat, you may need council consent and approval to confirm your space is eligible for the changes depending on your living situation.

Visit your local council and speak to the building and planning department. Through this, you will obtain a Development Application for the council to approve or reject. Discuss your council options, as there are various restrictions and policies to comply with before commencing.

Types of Granny Flats

Detached Granny Flat

A detached granny flat is a standalone secondary dwelling on a block that already contains the main dwelling. Building a detached granny flat can be perfect to use as an investment, as it has a separate entryway to your main house and most often a fence between the two buildings to create more privacy for your family or tenants.

Attached Granny Flat

An attached granny flat is joined to the main dwelling on the property and is designed to fit seamlessly with your home. By altering the granny flat’s orientation, we can either maximise your privacy or increase the occupants’ interaction.

Apart from the noticeable difference that an attached granny flat is attached by at least one wall to your existing house, there are some other key differences. The first and most crucial point is that a fire-rated wall will be required between the current house and granny flat. The second fundamental design feature is that there cannot be an internal entry door between the house and a granny flat. The granny flat is required to have its separate entrance.

Granny flat with Garage

Did you know you can build a granny flat with a garage attached? Well, you can! The State Environment Planning Policy (SEPP) permits a granny flat to be made with an internal living space of 60m2. A garage is classified as a non-habitable space and can be attached to a granny flat without being counted as part of the habitable area. This means you can add a fully enclosed garage (or carport) to your granny flat without losing any space! The garage can also have internal door access making rainy days much easier!

Two Storey Granny Flat

Two-story granny flats are becoming a lot more popular as investors and families realise the potential of placing one of these homes in their backyard!

Two-story granny flats come in different shapes and sizes, and however, like single-story granny flats, they are restricted to 60m2 of internal habitable space.

A two-story granny flat can include a double garage on the ground floor and a 60m2 granny flat above it. If you require a car space for the main dwelling, we can easily install a privacy wall between the two-car areas and separate entryways.

We have completed several two-story granny flats, and each of them has its unique features, including a balcony upstairs to maximise living space for indoor/outdoor living.

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Detached Studio

A detached studio is a habitable building used for alternative purposes such as a home office, entertainment area, art studio or guest room. A studio granny flat is considered an extension of the primary dwelling even though it is separate. You can also build this type of granny flat in a BAL40 or Flame Zone.

This dwelling type doesn’t contain any cooking or laundry facilities and isn’t used as a secondary dwelling. Building a studio granny flat is a great option if you work from home and create a small home office or extended family.

Granny Flat Size Restrictions

Council requirements will generally include a minimum land size before granting permission. You may think you have a large enough space. However, you need to consider any state or territory regulations of measurement before proceeding. Below is a brief explanation of the minimum and maximum measurement requirements in each state in Australia.

Granny flats in New South Wales – The individual’s property should be a minimum of 450 square metres before building a granny flat.

Granny flats in Queensland – Granny flats in Queensland can only be a maximum of 80 square metres. However, residents will not need to apply for council approval if the extension will be for a family member already living on the property.

Granny flats in Western Australia – Policies in Western Australia limit granny flat areas to a maximum of 70 square metres.

Granny Flats in South Australia – Detached dwellings in South Australia cannot include full kitchen and laundry areas and stick to 50 square metres of floor area.

Granny flats in Victoria – Dwellings or granny flats exceeding 300 square metres generally require an assessment to ensure the structure is safe and secure to proceed.

Granny flats in Tasmania – Additional dwellings must not exceed a floor area of 60 square metres.

Granny flats in the Australian Capital Territory – The maximum gross floor area for a granny flat is 70 square metres. Additional parking space is required, and the occupant must be providing care to, or receiving care from, a resident of the main dwelling.

Granny flats in the Northern Territory – The maximum floor area of granny flats is 50 square metres or 80 square metres, depending on the property’s type of zone. MJS Construction Group has the best range of dual occupancy builder services to help you create your dream house.

Things To Consider Before Building A Granny Flat

It’s hard to get approval to build a granny flat.

Some Australian states and local councils have strict planning and building regulations regarding the approval, construction and use of granny flats. However, in NSW, WA, NT, ACT and TAS, new planning policies have been introduced to increase affordable rental housing supply and availability. As a result, it’s easier to get the construction of a granny flat approved – provided all the required criteria are met.

It takes a long time to get approval.

In NSW, WA, NT, ACT and TAS, the timeline for approvals is relatively compact – much like the size of the property you’re trying to get approved. Current council approvals average between 6-8 weeks, and private certification is as fast as 10 days. However, in other states, the process can take up to a year with severe usage restrictions.

You need a lot of lands.

The minimum land size needed to build a granny flat can vary across local councils. A good guide is to have at least a 450m2 block of land. Even though you may have space, it’s important to remember that regulations limit the building of only one secondary dwelling on each lot.

The size of the granny flat doesn’t matter.

As a general rule of thumb, granny flats must be under 60sqm. The regulation does vary from state to state, with a few local councils allowing carports and porches to take up additional space (above the allotted 60sqm). Check what your local council provides before you commit to a design.

You have to subdivide your property.

You may be able to separate the mailing address and arrange for individual utility bills; however, building a granny flat does not permit the actual subdivision of your property – unless it’s already allowed under a local planning scheme.

The granny flat has to be detached from the main dwelling.

Whilst you can build a separate dwelling on your lot that is completely detached from the main house, there are also alternative building types to consider. For example, you can convert part of your existing home into an ancillary dwelling by separating one part of the house.

Alternatively, you can add an extension such as an extra room or add a second storey above a garage. The building above the garage is also known as a Fonzie flat, and in NSW, this does fall under different subdivision legislation.

No one wants to rent a granny flat.

A granny flat is a great rental prospect. If it’s well built, close to public transport, universities and supermarkets, it can be a desirable but small rental home. In fact, in Sydney’s competitive rental market, granny flats rent an average of $292.46 per week and are currently attracting a higher growth rate than houses or apartments.

You can’t use a granny flat for investment purposes.

With the easing of granny flat rental regulations in NSW, WA, NT, ACT and TAS, homeowners can now earn an income by renting out their granny flat. In other states, secondary dwellings can add to property values, with buyers attracted to the extra space for use as a home office or guest bedroom.

A granny flat is just a cheap, low-quality kit home.

Whilst there are many cheap, all-inclusive granny flat kits on the market, they’re certainly not your only option. Depending on your needs, you may opt for an architecturally designed granny flat that works harmoniously with the main dwelling. Every property is unique – so look for the solution that works best for your property and budget.

It’s hard to get finance.

Not all financial institutions are aware of your living requirements’ changing needs, so it’s essential to find a lender with experience in granny flat financing. They must offer the option of a construction loan or the choice to access the equity in your property for the specific purpose of building a granny flat. At Gateway, we offer Australia’s first purpose-designed granny-flat loan that makes it even easier for those wanting to add a secondary dwelling. Finding the right duplex build  is an important decision. Check out our range of the best home design constructions at MJS Construction Group.

Can I Build A Granny Flat In My Backyard?

Don’t assume that because your neighbour has one, you can have one too. Each state and territory has different laws governing secondary dwellings, with rules on block size and dwelling size and the distance you’ll need to leave between boundaries, trees and your existing house.

In NSW, the minimum lot size is 450 square metres (under complying development). Still, Development Application can be permissible for smaller lot sizes, and the maximum dwelling size is 60 square metres (in most cases). There are certain situations where your council area might provide you with a better granny flat size option under clause 5.4 of the Local Environmental Plan.

You can have a chat with one of our planners at Outlook Planning and Development to see whether you can build a granny flat on your site.

Who Can Live In A Granny Flat?

If you live in Melbourne, Brisbane or Adelaide, and you thought a granny flat was a great way to boost your cash flow, think again.

According to regulations in these cities, only immediate family or a “dependent person” can occupy your granny flat. You may be required to remove your granny flat in some instances if that person leaves or dies.

There is more choice across NSW, Western Australia, the Northern Territory, the ACT and Tasmania, where it’s generally acceptable to rent out your second dwelling. Research conducted by Gateway revealed 23 per cent of the country’s granny flats were used to generate rental income.

How Much Do Granny Flats Cost?

The cost for a granny flat can range from $20,000 to $200,000-plus. The cost of a granny flat can vary depending on the residence’s purpose and the quality you’re striving for. For example, for $24,000, you might secure a flat-pack DIY dwelling. $ 70,000 should cover installing a one-bedroom prefabricated dwelling, while custom designs start from around $120,000. The typical price for a one-bedder begins at $90,000, with a two-bedder starting from $105,000. At MJS Construction Group, we have the best dual occupancy selection to make your house a dream come true.

A granny flat can provide several benefits. You may use it for extra space, a guest room, a home for a relative, rental purposes or a playroom for the kids. It’s best to consider this before building to ensure you know who will benefit most and get the most use out of it. This, in turn, influences the design of the dwelling.

Many residents tend to build granny flats to boost their property’s value and rent it out to potential tenants. This can work as an excellent investment and allows for extra cash flow due. Speak to a professional to consider if the rent charged will cover the cost of the build.

Granny flats are also suitable for extra space for potential guests, like friends or relatives. Some relatives may also occupy the dwelling for a prolonged period, such as in-laws or grandparents. In this case, you may need to consider if the structure requires extra railings or ramps for any older individuals who may need them. Granny flats are great for privacy or entertainment spaces, including toy rooms, man caves or an office for the self-employed.

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