How Big Can A Granny Flat Be?

Granny flats have evolved from simple backyard additions to highly sought-after properties that serve a range of purposes. Whether you’re looking to house aging parents, create a private home office, or even generate rental income, granny flats provide a cost-effective and versatile solution. However, before you jump into construction, it’s essential to understand the regulations that govern the size of these secondary dwellings.

In Australia, the size of a granny flat is not one-size-fits-all. Different states and local councils have their own rules about what you can and can’t build. These rules are designed to ensure that your granny flat complies with the broader planning requirements of your area. Knowing the exact limitations and the nuances of these regulations can save you from costly mistakes down the track.

Here, I’ll discuss the regulations on granny flat sizes across Australia, share personal experiences to highlight common hurdles, and provide actionable tips to make the most of the space you’re allowed. Whether you’re in New South Wales or Queensland, I’ll help you navigate the specifics of building a granny flat that meets your needs while staying within legal limits.

Maximum Granny Flat Size Limits By State And Council

Building a granny flat in Australia is exciting, but it’s crucial first to understand the size restrictions in your area. With different regulations in each state and council, these limits can vary significantly. Here’s a quick reference table to help you get an overview of the maximum size limits for granny flats across Australia.

As you can see, the size limit can vary greatly depending on where you are located. Let’s dive deeper into each state’s regulations to ensure you’re on the right track.

New South Wales (NSW)

New South Wales has some of the most straightforward regulations for granny flats. If you’re planning to build a granny flat as a complying development (CDC), the maximum allowed size is 60 square metres for the internal floor area. This means you don’t need to go through the time-consuming process of applying for a full Development Application (DA).

Personal Experience: I’ve helped clients in Sydney navigate this process, and one key takeaway is that while a 60 sqm granny flat can be built without a DA, anything larger will need council approval. A client of mine wanted to build a 100 sqm granny flat, but it had to go through the DA process. This added several months to the approval timeline, so it’s important to factor that into your planning if you’re aiming for a bigger space.

Key Points in NSW Granny Flat Regulations:

• 60 sqm: For complying development.
• 100 sqm: Possible with a Development Application (DA).
• Height restrictions: Granny flats can’t exceed 8.5 metres in height.

Victoria (VIC)

In Victoria, the maximum floor area for a granny flat, also referred to as a secondary dwelling (SDD), is 60 square metres. However, there’s flexibility if you want to go up: two-storey granny flats are allowed as long as the total floor area doesn’t exceed the 60 sqm limit.

Real-life Example: A friend of mine in Melbourne wanted to build a two-storey granny flat. With the 60 sqm size restriction, we had to creatively design a compact ground floor with an open-plan kitchen and living area, and use the upper floor for a spacious bedroom. This design worked well, providing ample space while staying within the floor area limit.

Important Considerations in VIC:

• Maximum Size: 60 sqm for single-storey.
• Two-storey: Allowed as long as the total floor area doesn’t exceed 60 sqm.
• Council Approval: For larger or more complex designs, a full Development Application (DA) may be required.

Queensland (QLD)

Queensland is a mixed bag when it comes to granny flat sizes. Some councils, like Brisbane City, allow secondary dwellings up to 80 square metres, while others, like Sunshine Coast, permit up to 90 square metres.

However, it’s essential to keep in mind that the maximum size of a granny flat is also tied to the size of your primary dwelling. For example, in some areas, the granny flat cannot be more than 50% of the size of your main house.

Local Tip: I once worked with a family on the Gold Coast where their primary home was quite large. As a result, they were allowed to build a 90 sqm granny flat. This is a significant advantage in Queensland if your primary residence is spacious.

Queensland Granny Flat Guidelines:

• Maximum Size: Between 45 sqm to 90 sqm, depending on the council.
• Primary Dwelling: In some councils, the size of a granny flat cannot exceed 50% of the size of the main house.
• Height Restrictions: Typically 8.5 metres for two-storey flats.

Western Australia (WA)

In Western Australia, the maximum size for a granny flat is typically 70 square metres, but this can go up to 100 sqm in certain councils. This is one of the more flexible states for granny flat construction.

In my experience, the 100 sqm limit applies in larger councils, such as the City of Perth, while in more rural areas, it’s not uncommon to see even larger exemptions. Additionally, WA has a minimum granny flat size of 20 sqm, which is perfect for those looking to build a more compact space for guest accommodation.

South Australia (SA)

In South Australia, the size of your granny flat is determined either by a flat 60 sqm maximum or 70% of your primary dwelling’s size, whichever is smaller. For instance, if your main house is only 80 sqm, the maximum size for your granny flat would be 56 sqm (70% of 80 sqm).

This system offers flexibility, but it can be tricky if your primary dwelling is on the smaller side. The benefit, however, is that SA is often more lenient with approvals compared to other states.

Important Points for South Australia:

• Maximum Size: 60 sqm or 70% of the main house size.
• Council Review: The council may adjust the size based on the relationship between your main dwelling and the granny flat.

Tasmania (TAS)

Tasmania follows a similar approach to South Australia, allowing granny flats to be 60 square metres or 30% of the primary dwelling’s size, whichever is smaller. This is particularly useful for families with smaller homes looking to add a granny flat that won’t exceed the allowable size.

Australian Capital Territory (ACT)

The ACT offers considerable flexibility regarding granny flat size. The maximum allowable size for a granny flat in the ACT ranges from 40 sqm to 90 sqm, depending on zoning and property specifics.

Example: In Canberra’s outer suburbs, granny flats up to 90 sqm are permitted, giving homeowners the freedom to create spacious secondary dwellings.

Northern Territory (NT)

In the Northern Territory, the size of granny flats can range from 50 sqm to 80 sqm, depending on the council. Urban areas like Darwin generally have stricter regulations, with a limit of 50 sqm. Meanwhile, more rural areas allow up to 80 sqm, providing more flexibility for larger builds.

Strategies To Maximise Granny Flat Usable Space

Although the internal size of the granny flat may be capped, there are numerous ways to make the space feel larger and more functional. Here’s how to squeeze every bit of potential out of the area you have:

Adding Non-Habitable Areas: Decks, Patios, And Garages

One effective way to increase your granny flat’s usable space without exceeding the floor area limit is to incorporate non-habitable features like decks or patios. These spaces are typically not counted in the floor area calculation, meaning you can add an extra 30 sqm of living space, like my client did in Sydney when they added a large deck. It was a game-changer for entertaining!

Garages and carports are also valuable add-ons that won’t be counted towards the maximum size of your granny flat. So, if you have the space, building one of these can free up space inside for additional living areas or bedrooms.

Lofts And Roof Space

If your granny flat has high ceilings, consider building a loft or utilising roof space for storage or a small sleeping area. This can be a great way to increase the functionality of your granny flat without affecting the legal floor space limit. Keep in mind, though, that some councils may have specific rules about how much space can be classified as a loft, so it’s always worth asking first.

Other Important Granny Flat Size And Structure Considerations

When planning your granny flat, consider factors beyond just floor space limitations. Other key factors can impact how functional and livable the space is. Let’s dive into some important considerations for structure, layout, and design.

Minimum Floor Space Requirements

While the maximum size of a granny flat varies, there are minimum size requirements that can affect your design choices. In most Australian states, the minimum size for a granny flat is 40 square metres. This is the absolute minimum in most areas, but the size can vary slightly depending on the council or zoning regulations.

Real-Life Scenario: A couple I worked with in Melbourne was originally planning for a 35 sqm granny flat, but they found out that the local council required a minimum of 40 sqm for all secondary dwellings. They had to adjust their design, but it ended up being a blessing in disguise. By making the living area just a bit larger, they were able to incorporate more storage, and they ended up with a much more functional space.

Two-Storey Granny Flats

Two-storey granny flats can be a great solution for those who want to maximise their living space while adhering to size limits. In most areas, two-storey granny flats are allowed, but you’ll still need to stay within the overall maximum floor area specified by your local council.

For example, in New South Wales (NSW), you can have a two-storey granny flat, but the 60 sqm maximum floor area limit must be split across both levels. So, while you could theoretically have a smaller living area downstairs and a bedroom upstairs, the total combined space can’t exceed 60 sqm.

Local Experience: I once helped design a two-storey granny flat in Sydney’s northern suburbs. We had to be creative with the layout due to the restricted floor area. The downstairs featured a compact kitchen and living area, while the upstairs was a spacious loft bedroom. The design worked beautifully and made the space feel larger than it actually was. But, as with all two-storey designs, you’ll need to check the height restrictions for your area, as councils may have different rules regarding the overall height of the structure.

Height Limits And Other Restrictions

Height restrictions for granny flats are common across many local councils in Australia, and these limitations can affect how you design your secondary dwelling. Most councils restrict the height of a granny flat to around 8.5 metres. If you’re thinking of building a two-storey granny flat, be aware that there are usually additional rules that apply if the height exceeds 3.8 metres.

Personal Tip: In my experience, councils like Queensland’s Brisbane City Council are quite strict when it comes to height restrictions, especially for two-storey granny flats. If your granny flat’s height exceeds the limit, you may need to apply for a Development Application (DA), which can be time-consuming and expensive.

However, if you’re working with a sloped block of land, you may be able to use the slope to your advantage. The height measurement is typically taken from the natural ground level to the highest point of the roof, so if you have a property on a hill, you may be able to build a taller structure than on flat land. Just remember, you’ll need to check with your local council to make sure you’re complying with the regulations.

Building a granny flat in Australia is a fantastic way to add value to your property, provide extra living space, or create a rental income opportunity. However, it’s essential to understand the various regulations governing granny flat size limits in your state or council area. By navigating size restrictions effectively and employing strategies such as incorporating non-habitable spaces or building upwards, you can create a functional and comfortable living space within legal boundaries.