Most people start with a picture in their head before they ever look at a floor plan. A quiet space out the back for a parent, or a self-contained rental you can let out down the track. A one-bedroom granny flat often fits that picture well, and the floor plan is where it either works or feels cramped. So before you get attached to a particular look, it helps to understand what actually fits in the footprint, and what separates good one-bedroom granny flat floor plans from tight ones.
What fits in around 50m²
In NSW a secondary dwelling can be up to 60m² of internal living space, and plenty of one-bed granny flats land a bit under that, around 45 to 55m². That is enough for a genuine one-bedroom home, not a studio with a bed shoved in the corner.
A comfortable one-bed layout usually gives you:
- A bedroom big enough for a queen bed with a wardrobe, ideally a built-in.
- An open-plan living and kitchen so the space feels bigger than the number suggests.
- A bathroom, often with a European laundry (washer and dryer tucked into a cupboard) to save room.
- A covered entry or small porch, which does a lot for how the place feels day to day.
Fifty square metres sounds small on paper. Laid out well, it lives a lot larger than that.
What makes a one-bedroom granny flat floor plan work
The plans we see work best keep the wet areas grouped together. Put the bathroom and kitchen plumbing on the same wall or back to back, and you keep the build simpler and the costs down.
From there, the living and kitchen sit at the front, opening to the yard or a deck, and the bedroom goes to the quiet back corner away from the entry. That separation matters more than people expect, especially if a parent is living there and wants the bedroom to feel private.
Good natural light is the other thing worth chasing. A window in the living area facing north, where your block allows it, makes a small space feel open instead of closed in.
Common one-bedroom granny flat designs
One-bedroom granny flat designs come down to three shapes: a straight rectangle, an L-shape, and a narrow plan for a tight side boundary. The rectangle is the most common by a long way, because it's the cheapest to build and the easiest to get approved.
- Rectangle. Roughly 10 metres by 5 at 50m², with living and kitchen at one end and the bedroom at the other. Straight walls, a simple roof, almost no wasted hallway. It's the default for good reason.
- L-shape. The living area steps out to catch northern light or wrap a small deck, with the bedroom in the leg. It costs a bit more to frame and roof, and it earns that back when your block's orientation or an existing tree forces the shape.
- Narrow. Around 4 metres wide for a long strip beside the main house or down a battleaxe handle. Wet areas go on one wall and the living space runs along the windows, which is what keeps it from reading like a corridor.
Simple usually wins at this size. Every extra corner in the footprint is more frame, more roof and more flashing, and it rarely buys usable space in a 50m² plan. Granny flat house plans and layouts covers the same thinking across studio, one-bed and two-bed.
Can you fit a one-bedroom granny flat under 50m²?
Yes. A small one-bedroom plan at around 40 to 45 square metres still gives you a separate bedroom, a full bathroom and an open living and kitchen area. What it gives up is spare living space and storage, not rooms.
The things that go first are the second seating zone and the internal laundry, so a European laundry in a cupboard and a single run of kitchen bench do the work instead. A covered entry or a small deck off the living area buys back some of the openness without counting toward the internal floor area.
Going smaller doesn't shrink the budget as fast as the metres. The bathroom and the kitchen carry most of the fit-out whatever the footprint, so the saving sits mostly in structure and finishes. Our granny flat cost guide goes through how studio, one-bed and two-bed compare.
Small choices that make a big difference
Once the rough shape is set, a few decisions do the heavy lifting:
- Ceiling height. A slightly higher ceiling, say 2.55m or above, makes a compact room feel generous.
- Where the front door lands. Walking straight into the living space usually feels better than a tight internal hallway eating your square metres.
- Storage. A built-in wardrobe and a bit of linen storage keep the place from feeling cluttered fast.
- Indoor-outdoor flow. A modest deck or pergola off the living area effectively adds a room in the warmer Illawarra months.
None of these change the footprint much. They change how the finished granny flat feels to live in.
Who a one-bed suits
A one-bedroom plan is not the right answer for everyone, and that is fine. It tends to suit:
- Rental. One-bed granny flats are easy to let and simple to maintain, which is part of why they are so common across Wollongong and the Illawarra.
- A parent or in-law. Close by, single level, no stairs, and their own front door. It works for older parents who want independence without being far away.
- A teen or young adult. A bit of separation for an older kid studying or saving, without leaving home entirely.
If you need two bedrooms, for a couple with a child or a longer-term family member, it is worth pricing a two-bed against a one-bed early. The bigger plan costs more, so treat any figure you hear as a starting point, not a quote. We would rather have that conversation up front than have you commit to a layout that feels tight in a year.
Getting the plan approved
Many one-bed granny flats in NSW can go through complying development (CDC), which is generally faster than a full development application, provided your block and the design meet the rules. Some sites do not qualify and need a DA instead. Lot size, setbacks, easements, and overland flow all come into it, and the Illawarra and Southern Highlands have plenty of sloping and irregular blocks where this matters.
The honest advice is to confirm the approval path for your specific address with your local council or a private certifier before you lock in a plan. At Ovas Build we handle the design, the council approval, and the build under one point of contact, so the granny flat plans you settle on are ones we already know can be approved on your block.
Getting the layout right on paper, and checked against the rules for your address, is the part that makes the rest of the build go smoothly.
Want a hand with this at your place? Get a free quote or call 0434 037 851.