Picture a family in Corrimal with a clear brief. Two teenagers who want their own space, a grandparent who might move in next year, and a backyard that looks big enough for all of it. They’ve seen a few ads for a 3 bedroom granny flat and want to know if they can build one. The honest answer is “probably, but you may not like what you get”. This post explains why, and what usually works better.
The 60m² limit decides almost everything
In NSW, a granny flat approved through a Complying Development Certificate (a CDC, the fast approval route handled by a private certifier instead of council) can have up to 60m² of floor area. Decks and balconies aren’t counted. That number doesn’t change because you want more bedrooms.
So the real question isn’t “can I have three bedrooms?” It’s “how do I want to split 60m²?” Every granny flat still needs a kitchen, a bathroom, a living area and somewhere to wash clothes. Those rooms take roughly the same space whether there’s one bedroom or three. Each extra bedroom comes out of what’s left.
If you want the full picture on floor area, decks and what counts, we’ve covered it in our guide to granny flat size rules in NSW.
Three bedrooms can fit. Here’s what it costs you in space
You can draw three bedrooms inside 60m². Plenty of builders advertise exactly that. But something has to give, and it’s usually the parts of the home people spend the most time in.
Put a three bedroom plan next to a two bedroom plan of the same size and the trade-offs jump out:
- a living and kitchen area squeezed down to a corridor with a couch
- bedrooms that fit a bed and not much else
- little or no built-in storage
- one bathroom shared by three bedrooms’ worth of people
- a laundry tucked into a cupboard
None of that is against the rules. It’s just tight. For a short stay it can be fine. For a household living there every day, it can feel cramped quickly, and a cramped layout is harder to rent out later if your plans change.
Why the ads make it look easy
Search for a 3 bedroom granny flat and most of what comes up is Sydney builders’ display designs and project galleries. They’re real, and they can be approved. Some of them, though, sit on a different path from a standard backyard granny flat.
A few are built under a council Development Application (a DA) where the local plan allows a larger secondary dwelling. Some are really a second full house, which is a dual occupancy and a different type of approval altogether. Others are 60m² designs with three very small bedrooms.
Going over 60m² takes you out of the CDC route and into council. On our numbers, a DA usually takes 3 to 6 months or more, compared with about 30 days for a lodged CDC. Council can also only approve a bigger granny flat where its local planning rules allow one, so lodging a DA is no guarantee.
Two bedrooms and a flexible space usually does the job better
Two good bedrooms leave room for a proper living area, a kitchen you can actually cook in, and storage that keeps the place livable. If someone needs a desk or a spare bed now and then, a study nook or a covered deck that works as an outdoor room can cover a lot of what the third bedroom was meant to do. And because the deck doesn’t count toward the 60m², it adds usable space without eating into the floor area limit.
That’s the thinking behind our two bedroom granny flat designs. They suit a parent moving in, adult kids or a tenant, and they still make sense if your household changes in five years.
This one surprises people: a smaller bedroom count often feels like the bigger home.
When you genuinely need three bedrooms
Sometimes two really won’t cut it. A family of four moving out the back while they rent the main house, for example, needs three proper rooms. In that case it’s worth looking past the granny flat for a moment.
Extending the main house can give you more floor area, but it stays part of the main house rather than a separate home, and it has its own approval rules. We compare the two side by side in our granny flat vs extension guide. A dual occupancy is another option on some blocks, but it’s a bigger project and a separate conversation from a granny flat.
What we’d steer you away from is squeezing three rooms into 60m² just to tick a box. If the rooms are too small to use, you’ve paid for a bedroom count, not a home.
Your block sets the limits before the floor plan does
Whatever layout you pick, the block has to pass first. To qualify for a CDC, the lot needs to be at least 450m² and at least 12 metres wide at the building line of the existing house, with residential zoning. The granny flat needs side setbacks of at least 0.9 metres and a rear setback of at least 3 metres, and only one secondary dwelling is allowed per lot.
Many Illawarra blocks clear those marks without trouble. Others have flood affected land (common around Lake Illawarra and low lying parts of Dapto and Fairy Meadow), heritage listings, sewer mains or steep slopes that change what you can build. That’s worth knowing before you fall for any floor plan, three bedrooms or two.
Once a CDC is granted, signing the construction contract to breaking ground is typically 1 to 2 weeks, and our build runs for about 10 to 14 weeks to handover.
Common questions about 3 bedroom granny flats
Can I build a 3 bedroom granny flat in NSW?
Yes, as long as it stays within 60m² of floor area and meets the other CDC rules. The catch is space: three bedrooms inside 60m² leaves a small living area and very little storage. Going bigger means a council DA, which council can only approve where its local plan allows.
What is the maximum size of a granny flat in NSW?
Under the CDC rules, a granny flat can have up to 60m² of floor area. Decks and balconies aren’t included in that figure, which is why a good deck can make a 60m² home feel a lot bigger.
Is a 3 bedroom granny flat better than a 2 bedroom?
Usually not, within the same 60m². Two bedrooms gives you rooms you can actually furnish and a living area that works. Three bedrooms makes sense only if you genuinely need three separate sleeping spaces and can live with smaller rooms everywhere else.
Do I need council approval for a 3 bedroom granny flat?
Not if the design is 60m² or less and your block meets the CDC rules, such as the 450m² minimum lot size and 12 metre width. A private certifier can approve it, typically in about 30 days once lodged. If the design is larger, or the block has constraints like heritage or flooding, it goes to council.
Can I rent out a 3 bedroom granny flat?
Yes, a granny flat in NSW can be rented to a tenant. It has to stay in the same ownership as the main house, so it can’t be subdivided or strata titled and sold off on its own. Tenants also tend to value a usable living area over an extra small bedroom.
If you’re trying to work out how many bedrooms your backyard can really hold, we’re happy to look at your block and show you what fits. Have a look at our 2 bedroom granny flats across the Illawarra and Southern Highlands, then get in touch and we’ll talk through the layout that suits your family.
