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Can You Build a Granny Flat Above a Garage?

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When thinking of ways to bring more space into your granny flat, you may be wondering – can you build a granny flat above a garage?


Yes – you can build a granny flat above a garage. As long as you meet the regulations set by your local Council, and have an engineer inspect your property before submitting your Development Application (DA), this is possible. 


In this post we cover whether your Council will allow you to build one. Plus;


DON'T PAY A FORTUNE FOR YOUR GRANNY FLAT. Find out how to deal with council and build a granny flat for the lowest cost possible. Learn More.

  • The best layout a granny flat above a garage.
  • Ways to insulate.
  • Where the plumbing will go.
  • Last of all, what extra foundation will need to be added when building a granny flat above a garage.


Common Footprint You Will Have to Work With


A garage is classified by Council as a “non-habitable space“. However a common alternative is to add a granny flat above a garage, and the entire second-storey can have the same maximum floor space restrictions as a typical granny flat.


An example of how a granny flat above a garage can look


However, it is important to note that, the taller the building gets, the more your setbacks will increase, in order to compensate for its’ height. These will start to be applied once your building height exceeds 3.8m. And affects the rear and side setbacks you can build towards on your property.


The general rules are as follows:


  • Rear Setbacks – Any height above 3.8m must be TRIPLED and added to the 3m that is already applicable.
  • (i.e. if your building height is 5.5m, your Rear Setback will be 1.7m x 3 = 5.1m + 3m = 8.1m).
  • Side Setbacks – Any height above 3.8m must by DIVIDED BY FOUR and added to the 0.9m that is already applicable.
  • (i.e. if your building height is 5.5m, your Side Setback will be 5.5m/4 = 1.375m + 0.9m = 2.275m).


It is also important to note that each state and Council has their own restrictions as to the maximum height your granny flat is allowed to be.


So, I suggest that you contact your local council to find out your exact regulations.


Will Council Allow You to Build One


Each Council will have its’ own regulations on 2-storey granny flats – such as your height restrictions. As long as you meet these standards, you should be approved to build a granny flat above a garage.


As such, I recommend that you contact your Council before making any plans, to find out what their rules on 2-storey granny flats are, and what their approval process is.


For some guidance on how to build a granny flat with a garage that ‘fits in’ with your surrounding neighbourhood and your primary dwelling, you can read my article on:



How to Best Layout a Granny Flat Above the Garage


A great layout for a granny flat above the garage is to have:


  • A double garage and a verandah on the first floor
  • Bedrooms and the master bedroom can have its’ own balcony.
  • A combined bathroom and laundry.
  • A full kitchen with an open plan dining and living area that has plenty of windows.


The reason this layout works so well is that neither the garage, verandah or balcony are classified as “habitable space”. So these won’t take up valuable space you are restricted to. Meaning, they can all be added into your design without taking any area at all from the floor space that you are allowed.


Also, simply combining rooms (i.e. the laundry and bathroom), and having an open plan kitchen, dining, and living area, has reduced 3 unnecessary internal walls that take up valuable floor space.


Natural light is also important to create a spacious and homely feeling, so having more than one outdoor area and lots of windows in the living area is ideal.


Open plan layouts can be achieved above a garage


Keeping the balcony in the master bedroom means you don’t have to worry about the safety of small children, or even visitors. However, it will still provide natural light, as well as lovely views, and a great balance between the indoor and outdoor living areas, as will the abundance of windows in the living area.


A great example of a granny flat above a double garage can be seen at Backyard Grannys.


Now, the staircase – where should this be placed?


The perfect place to put your staircase is up against the wall. Let’s say your verandah on the ground floor is on the left, then place the staircase to the right.


The reason for this is that it will not use any valuable floor space – in fact, if designed accurately, it can maximise your floor space as you will be able to use the space underneath the stairs for storage.


Should You Insulate the Floor?


This is a very simple answer – yes.


But the answer may possibly for a different reason than you might think. The insulation will create an acoustic barrier. Use these barriers to block the noise between the two dwellings. Acoustic batt insulation both in the walls and the floors can minimise the noise and decrease sound vibrations by up to 75%.


This is a great option for sound-proofing and increasing the feelings of privacy and separation for the residents in the main home and the occupants of the granny flat.


Where Will the Plumbing Go


This can be quite difficult, as a garage typically is not already connected to any water utilities.


It is important to that you first know;


  • Where your main water will be coming from.
  • Whereabouts the Council mains are located, and
  • How you will guide the waste water away from your granny flat.


So, if you make a thorough survey of this, you will then be able to map out your plumbing.


I have written a definitive guide on plumbing for granny flats, if you would like to learn more about this.


Effectively, the pipes will have to run either outside the garage wall, if your local council allows this or within the internal wall of the garage below. The great news is that you can simply create a cavity to cover these pipes on the wall. So it won’t look terrible in the garage.


What Added Foundation Will Need to be Added


A granny flat built above a garage will need a lot more work done to the structure and foundation than a traditional granny flat.


The majority of the time, either more steel or more timber beams will need to be installed, as these will assist with supporting the weight of the second storey. As well as these extra requirements (which are known as ‘sub-structure’), additions may need to be made to the foundation on which the granny flat is built.


The foundation may need to be underpinned and strengthened. This means it may need to be braced from below – a solid and strong concrete slab may need to be built from below ground level.


Exactly what will be required for your sub-structure and foundation will need to be correctly designed and engineered by a certified engineer.


However, an example is the use of waffle pods to strengthen the slab, as can be seen in this foundation for a 2-storey design at Backyard Grannys.




It is possible to build a granny flat over a garage. It is actually a great design, as it allows you to have:


  • A double garage on the ground floor
  • Your total allowed living area on the granny flat above it


This is as a garage is classified as a “non-habitable space”. Meaning, none of the floor space of which is allowed within your Council is deducted if you add a garage. So this simple addition offers you a sense of space like no other.


You can also add a verandah or decking downstairs and an upstairs balcony, as these too are not “habitable” areas, and so not taken from your available floor space. With the addition of more outdoor areas, and windows, you will bring in more natural light, all of which will create a feeling of spaciousness.


Simply combining rooms, and having an open plan kitchen, living and dining area can also reduce internal walls, creating even more space. Positioning your staircase up against the wall will not take up any valuable floor space – it can actually maximise your floor space, allowing you to use the area underneath as storage.


Using acoustic batts to insulate the floor will create a great acoustic barrier, adding to the feelings of privacy and separation between the two dwellings.


Simple things to keep in mind are that, you will need a solid concrete foundation so that it can support the weight of a second storey. Ensure you have the land space, as the taller your granny flat gets, the further your setbacks will increase.


Also, every state and Council will have different restrictions on the height you can build your granny flat.


So, I suggest you contact your local Council and ask for their regulations and approval process. After you have made that call –  what are you waiting for, start designing! The options available to you are just incredible, so I hope this article has motivated you to build your very own granny flat above a garage.