“If I’m spending the money anyway, why wouldn’t I just do two bedrooms?” We hear some version of that on almost every site visit. Usually the next question is the opposite one: “Or am I paying for a room nobody will use?” Both are fair, and the answer depends mostly on who will live there. Choosing between a 1 bedroom vs 2 bedroom granny flat is the first real design decision on most projects we quote, and it shapes everything that follows.
Here’s how we think it through with owners across the Illawarra and Southern Highlands.
Both options sit under the same 60 square metre ceiling
In NSW, a granny flat (the planning rules call it a secondary dwelling) approved as complying development is capped at 60 square metres of floor area. That limit doesn’t change with bedroom count. So you aren’t choosing between a small building and a big one. You’re choosing how to divide roughly the same footprint.
That matters more than people expect. A 1 bedroom layout close to the full 60 square metres feels generous: a proper living room, a kitchen with real bench space, a bedroom that fits a queen bed and wardrobe with room to walk around it. Put two bedrooms into the same area and every room gets a bit tighter. Still very liveable, and plenty of people prefer it, but the trade is real. If you want the detail on what counts toward that 60 square metres, we’ve covered it in our post on granny flat size limits in NSW.
You don’t have to build to the full 60, of course. A 1 bedroom flat can be a smaller building, and that is where most of its cost saving comes from.
The second bedroom costs less than you’d think
This one surprises people. The expensive parts of a granny flat are the kitchen, the bathroom, plumbing and drainage, the electrical connection, site works and the approval itself. You pay for all of those whether you build one bedroom or two.
A second bedroom adds a wall or two, a door, a window, a wardrobe, some extra slab and roof if the building grows, and a little more electrical work. That isn’t free. But it’s a much smaller slice of the total than the bedroom count suggests. Going from one bedroom to two doesn’t double anything.
Where a 1 bedroom flat does save real money is when it is also a smaller building overall. Less slab, less frame, less roof, less cladding. If budget is the main driver, a compact 1 bedroom design is the way to get there. Our guide to what a granny flat costs in NSW walks through the line items, so you can see which ones move with size and which ones don’t.
Who is moving in decides most of it
Nearly every conversation we have about bedroom count comes back to one question. Who’s going to live there? Once that’s settled, the right layout is usually obvious.
An ageing parent
For one parent, or an older couple, a well planned 1 bedroom flat is often the better home. The bedroom can be big enough for a walker or a wheelchair turning circle. The bathroom can be larger, with a hobless shower and room for grab rails. There’s less to clean and fewer rooms to heat on a cold Robertson morning. Some families still want a small second bedroom for a visiting carer or a grandchild staying over, and that’s a real need. But if it comes down to a second bedroom or an accessible bathroom, the bathroom wins.
An adult child
Young adults saving for a deposit tend to want space to work from home, have a partner stay, or share with a friend to split costs. Here a second bedroom used as a study or guest room earns its keep. It’s a common setup for families from Thirroul up to Helensburgh who want to keep the kids close while they save.
A tenant
This is where the decision gets more interesting, and it’s the one investors ask us about most.
For rental income, think about who will apply
A 2 bedroom granny flat can house a couple with a baby, two friends sharing, a single parent with a child, or someone who works from home and wants a separate office. A 1 bedroom flat suits singles and couples. That’s a narrower group, but not a small one.
Location shapes who turns up to inspections. Around Wollongong, Gwynneville, Keiraville and Fairy Meadow, close to the university and Wollongong Hospital, a lot of renters are singles and couples, so a good 1 bedroom flat has a natural market. In family suburbs like Dapto, Shell Cove and Oak Flats, a second bedroom opens the door to young families and sharers. In the Southern Highlands, around Bowral, Mittagong and Moss Vale, flexibility tends to count because the renter mix is broad.
We won’t quote a rent figure in a blog post, because rents shift and vary street to street. What we can say is that a second bedroom usually widens the pool of people who will apply. More applicants means shorter vacancies and a better chance of finding a tenant who stays. For most of the investors we work with, that flexibility is the main argument for two bedrooms.
What you give up with each layout
Neither option is free of compromise. On a full size build, they usually stack up like this:
- 1 bedroom: bigger living area and bedroom, easier to make accessible, simpler to furnish. Fewer tenant types, and no spare room for guests, a carer or a home office.
- 2 bedroom: suits more households and adapts over time, with a spare room that can be a study, nursery or guest room. Smaller rooms throughout, and the second bedroom is often only just big enough for a double bed.
One thing we tell every owner: think about the next ten years, not just the next occupant. A flat built for Mum today might house a teenager, a renter or a home business later. Two bedrooms handle those changes more easily. One bedroom does fewer jobs, but it does them better.
Your block may make the choice for you
Sometimes the land decides. On a narrow block in Woonona or Bulli, or a sloping one hard up against the escarpment, the usable space behind the main house may not fit a full 60 square metres once setbacks, access and existing structures are allowed for. Then a smart 1 bedroom design might be the only thing that fits. If even that is a squeeze, our studio granny flat options are worth a look.
On bigger Southern Highlands blocks it’s the reverse. Space is rarely the issue, so the question goes back to who will live there and what you need the flat to do.
We build fixed designs that are CDC approved, which keeps approvals quicker and builds more predictable. It also means we can show you a real floor plan for each option on your actual block, rather than talking in theory. If you’re leaning toward the extra room, have a look at our two bedroom granny flat designs to see how the space gets divided in practice.
Three questions that usually settle it
If you still can’t pick, answer these honestly:
- Who will live there first, and who might live there in five to ten years?
- Is the lowest possible upfront cost more important to you than rental flexibility?
- Does your block comfortably fit a full size flat once setbacks and access are allowed for?
If your answers are “a parent or a single person”, “yes” and “no”, a 1 bedroom flat is probably right. If they’re “a tenant, or not sure yet”, “no” and “yes”, go for two bedrooms. Mixed answers are normal, and that’s exactly what a site visit sorts out.
If you’d like to see both layouts on your own block, start with our 2 bedroom granny flat range and ask us to price a 1 bedroom alternative alongside it. You can also call the team on (02) 4203 3554, Monday to Friday, 7:00 AM to 5:00 PM.
Common questions about 1 and 2 bedroom granny flats
Is a 1 bedroom or 2 bedroom granny flat better for investment?
For most rental projects we lean toward two bedrooms, because more types of tenant can use it and vacancies tend to be shorter. A 1 bedroom flat can still work well near the university, the hospital and the Wollongong CBD, where many renters are singles and couples. Your suburb and budget make the final call.
How much value does a 2 bedroom granny flat add?
It depends on the property, the suburb and how well the flat is built and laid out, so there’s no honest single number. Buyers generally see an approved, self contained second dwelling as a strong feature, especially one that already earns rent. A second bedroom widens the appeal to buyers who want room for family or a higher paying tenant.
What is the ideal size for a granny flat?
For most owners it’s as close to the 60 square metre NSW limit as the block allows, because the fixed costs (kitchen, bathroom, connections, approval) are the same either way. A smaller flat makes sense when the budget is tight or the block is small or awkward, and that is usually where a 1 bedroom design fits best.
Can you fit two bedrooms in a 60 square metre granny flat?
Yes, comfortably. Most 2 bedroom granny flats in NSW are designed around the 60 square metre limit, with open plan kitchen and living, one bathroom and two bedrooms. Rooms are a little smaller than in a 1 bedroom flat of the same size, but a good layout keeps it feeling open.
What are the disadvantages of living in a granny flat?
The main ones are less space and less privacy than a separate house, since you share the block with the main home. Good design helps a lot: a separate entry, windows that don’t look straight into the main house, and a sensible position on the block. Picking the right bedroom count for the people living there matters too, because a cramped layout is the complaint that comes up most.
