Are granny flats SA's next property trend?
For years, the humble granny flat was pretty much what its name suggested - a small place out the back for Mum or Dad.
Not anymore.
With housing affordability under pressure, adult children staying at home longer and families looking for ways to support ageing parents, that patch of backyard behind the house is starting to look a lot more interesting.
South Australia's planning rules have also changed. What planners call “ancillary accommodation” can now be self-contained, and restrictions that previously limited who could occupy or rent granny flats have been removed. The changes were deliberately introduced to increase housing choice and potentially add more properties to the rental market.
They're not just for Granny anymore
The name is probably becoming the least accurate thing about them.
Today's backyard dwelling might provide a home for an ageing parent who wants independence without being isolated, but it could just as easily accommodate an adult child saving for their first home, a family member following a separation, or a tenant providing the homeowner with additional income.
For some families, it can also offer a middle ground between everyone living under the same roof and living completely separately.
That's particularly relevant as our housing needs change. South Australia's planning reforms have specifically recognised ancillary accommodation as one way of quickly increasing housing diversity and supporting people to age in place.
South Australia's rules have changed
This is where things have become particularly interesting.
Changes introduced in late 2023 removed restrictions preventing granny flats from being rented to people who weren't related to occupants of the main home. Further reforms adopted in 2024 allowed ancillary accommodation to be self-contained, meaning it can have its own kitchen, bathroom and laundry.
The maximum floor-area criterion was also increased from 60 to 70 square metres as part of those reforms, with the State Government saying the additional space would improve accessibility and make granny flats more realistic options for ageing in place and younger adults.
That potentially makes the modern granny flat far more useful than its predecessor because it can feel less like someone's spare room at the bottom of the garden and much more like a small home.
A possible answer to the adult-kids-at-home dilemma
Anyone with adult children knows there can be a rather large gap between living at home and being ready to buy a home.
A backyard dwelling can potentially bridge some of it.
An adult child gets their own front door, bathroom, kitchen and living space while remaining close to the family home. Parents get their house back - or at least some of it.
Later, the same building might accommodate an ageing parent, become rental accommodation or serve another purpose as the family's circumstances change.
That flexibility is arguably one of the biggest attractions. Rather than building for one very specific need, homeowners can think about how the space might be useful over several decades.
Then there's the rental equation
The ability to rent ancillary accommodation to someone outside the family has opened another possibility. For a homeowner with sufficient land, a well-designed secondary dwelling could potentially create rental income without buying another property.
It could also make better use of established suburbs where the roads, shops, schools, public transport and other infrastructure already exist.
But this isn't simply a case of ordering a cabin, dropping it in the backyard and putting it online for rent.
In South Australia, construction of ancillary accommodation requires development approval, including planning and building approval. It is treated as a habitable Class 1a structure under the National Construction Code, with requirements to comply with structural safety, fire provisions and essential services. Granny flats must not be inferior accommodation.
The backyard still has to work
A 70-square-metre building may sound relatively modest but put it into a suburban backyard and things can become complicated surprisingly quickly.
Where will it sit? How will people access it? What happens to private open space? Where do cars go? Can occupants come and go without walking through the main family's entertaining area? What about overlooking, shading and neighbours?
Then there are the practical services. Water, electricity, wastewater, stormwater and potentially separate energy arrangements all need consideration. So does the relationship between the new accommodation and the existing house.
A clever floor plan doesn't necessarily make a clever site plan. The best backyard dwellings should feel as though they belong on the property rather than having been squeezed into the last available rectangle of lawn.
Don't forget the person who might live there
This is especially important when the plan involves an ageing parent.
A building designed for someone in their 60s today may need to work very differently for that same person in their 70s or 80s. Steps, narrow doorways, tight bathrooms and awkward access might not matter initially, but they can become significant later when the occupant becomes frail or ill.
Thinking ahead could mean easier access, a bathroom with room to manoeuvre, good lighting, fewer level changes and a sensible connection between the granny flat and the main house.
Accessibility doesn't have to make a home feel institutional. Done well, it simply feels like good design.
Small building doesn't always mean simple building
There's also a temptation to assume that because a granny flat is small, it will automatically be straightforward and inexpensive to build – and that’s not the case. It still needs a kitchen, bathroom, toilet and laundry facilities. These rooms are the most expensive elements in any house or flat.
Site access can affect construction costs. Existing sheds, trees, retaining walls, drainage and underground services can complicate where a new building goes. Older properties may have additions or structures that don't quite match the original plans – and squeezing a kitchen, bathroom, bedroom, storage and living space into a relatively small footprint can actually make good design more important, not less.
Before falling in love with a display model or a floor plan online, it pays to understand the property it's supposed to sit on.
One backyard, several generations
Perhaps the most interesting thing about the granny-flat revival is that it reflects a broader change in the way we think about housing.
The traditional model - children leave home, parents stay put and grandparents eventually move elsewhere - doesn't fit every family anymore.
South Australia's planning system is exploring other forms of shared-site housing too. New provisions for co-located housing, introduced in 2025, are intended to support different household types and ageing in place while allowing multiple homes to share a site in a more integrated way. That's different from a granny flat, which remains secondary to the main dwelling, but it points to the same bigger conversation about how our suburbs might accommodate changing households.
For some Adelaide homeowners, the answer might already be sitting beyond the back door.
