You no longer need a granny to have a granny flat in the act!

Jun 22, 2019

secondary residence regulations canberra

Following regulation changes in 2013, you no longer need a granny to have a granny flat in your backyard in the ACT.

While granny flats used to be restricted to caring for an older relative or family member, they are now used for a wide variety of purposes including:

  • Renting it out for money
  • Creating separate accommodation for parents or teenagers
  • Adding an external home office or studio
  • Making use of a large block that cannot be subdivided

The official name for a Granny Flat is a “Secondary Residence”, and yes, there are a whole lot of regulations that go with building one!

In essence, adding a granny flat to your home is similar to building a house. It must comply with its own set of regulations and be approved and signed off by a building certifier.

Building a granny flat can cost upwards of $100,000. However, if you are planning to build a new home or do a knock down rebuild, you may be able to absorb some of the cost into the actual home build. This might require you to think well in advance about your needs for the future, but adding it in from the start means you don’t have to worry about it later on; especially when certain design issues could make it impossible.

For example, in deciding to build a granny flat in conjunction with a new home, you may choose a double storey home design instead of a large single storey – to allow plenty of space in the backyard. You might also be more focussed on finding the right kind of block (larger than 500m2 and reasonably flat). In terms of design, you can easily match design choices to create a complementary feel.

If there is a possibility that the granny flat will be rented out, you can arrange for it to have separate water, electricity and gas supply (so you can keep a meter on usage and bill accordingly). Just keep in mind that if you do choose to rent it out, you will be subject to land tax on the whole of your property.

Granny flats are very different from dual occupancy, and can never be sold separately to your house. They also must comply with Adaptable Housing Standards, in the event that a disabled person should (at any time) need to live in the flat. This doesn’t mean incorporating disabled access right away, but being “adaptable” so that the design is easily changed in the future.

Other rules for secondary residences include:

  • Block size must be 500m2 or larger
  • Granny flat floor space must be between 40m2 and 90m2
  • The size of the house plus the flat must comply with the total plot ratio allowable for the block
  • Only the primary residence owner can own the granny flat
  • Property must be zoned ‘residential’
  • One granny flat per property
  • Granny flat must have clear, unobstructed pedestrian access

It is your choice whether you want to have the granny flat connected to your house or standing alone in the backyard, and whether you want more than one bedroom and one bathroom.

The best way to find out what is allowable (and possible) is to discuss it with your building designer right from the start. If they know you want a granny flat, they can plan for it properly and ensure that both the house and flat comply with regulations and complement each other well.

Granny flats can make a unique and potentially profitable addition to any home build. And if you take the time to think about it early on, it will become a seamless addition to the building process and a part of the home that will serve your family for many years to come.

For more information about building in the ACT, or the knock down rebuild process, please call Rosin Bros on 6247 4799 or email

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