A one-bedroom flat with the long wall given over to windows. The plan decided that long before the facade did.
Every older neighborhood in Atlanta has a few of them tucked behind the main house: the carriage house over the garage, the little cottage at the back of a Buckhead lot where a grandmother lived, or a newlywed couple, or a tenant who quietly paid the mortgage for a decade. Australians call the same thing a granny flat, and I have come around to the name. It says exactly what the building is for. A small, self-contained home with its own kitchen and bath, on the same property as the main house, built for a person you want close.
Here is the mistake almost everyone makes with one. They fall for the facade first. The Hamptons cladding, the pretty roofline, the color of the front door. I understand the impulse. I came up as a painter and I am as guilty as anyone of being seduced by a finish. But a small house is unforgiving in a way a big one is not. There are no spare rooms to absorb a bad decision. Granny flat floor plans decide where the light falls, whether the bed has walking room on both sides, and how private the place feels from the kitchen window of the main house. Settle the plan first. The look is far easier to choose once you know what you are dressing.
Start with who is going to live there
Before you compare a single set of granny flat floor plans, answer two questions. Who is this for now, and who might it be for in ten years? An aging parent, a twenty-four-year-old saving for a down payment, and a tenant want very different things from the same few rooms, and the plan that suits one can quietly fail the next.
One person or a couple is usually happier with one bedroom. That frees the square footage for a living area you can actually put a sofa and two chairs in, and for a bedroom that fits a real wardrobe instead of a rail behind a curtain.
Two bedrooms earn their keep only when the second room has a job. A grandchild who stays over, a study, a place for a carer to sleep. If the room would sit empty ten months of the year, give that space back to the living room. An empty bedroom in a 700-square-foot house is a very expensive closet.
Size is about proportion, not just square meters
Ready-made granny flat plans from the larger builders tend to run from about 45 to 65 square meters, which is roughly 485 to 700 square feet. On paper, a 20-square-meter difference sounds like a rounding error. Inside a home this compact it changes how every single room feels. Proportion is my whole trade. My grandmother drove me around Buckhead pointing out the houses where the windows were the right size for the wall, and that language of proportion is the one to speak here, at any scale.
How the area is divided matters as much as the total. At around 65 square meters you will find granny flat floor plans with one bedroom and others with two. Same footprint, two very different homes. The one-bedroom version gives you a living and dining area that feels generous. The two-bedroom version trades some of that generosity for flexibility. Neither is wrong. You just have to know which one you are buying.
One practical step before you fall in love with anything: check the local planning rules. Councils and counties alike cap how large a secondary dwelling can be, and some set conditions on who is allowed to live in it. Better to learn that from the planning office than from a letter after the slab is poured.
Read the footprint for light and outlook
Footprint shape is the easiest thing to skim past on a plan and the thing I would look at first.
A near-square layout of roughly 6.6 by 6.8 meters, call it 22 by 22 feet, is compact and sits comfortably in a tighter backyard. A wider, shallower layout closer to 9 by 6.6 meters, about 30 by 22 feet, gives you one long wall. Long walls are where the windows go. Face that side toward the sun and, depending on the plan, the living area and the bedroom can both share the light and the view instead of fighting over it.
So take the plan outside with you. Stand roughly where the flat would sit. Watch where the afternoon sun lands and think honestly about what you would see from the sofa. If the answer is the neighbor's fence, you either move the flat or you move the windows. This is also where a mirror earns its place later on. Every room could use one, and a small room with a good window and a mirror hung opposite it reads twice its size.
Freestanding or built in
Not every granny flat lives at the bottom of the garden. Some are built within the main home or attached to it and are still fully self-contained.
Freestanding almost always means more privacy for both households. That separation matters to a tenant, and it matters just as much to an adult child who wants genuine independence rather than a bedroom with a longer hallway. An attached or internal flat keeps everyone closer, which suits a parent who may need a hand nearby, and it works on a lot that does not have much backyard to spare.
Think long term either way. The layout that suits a tenant this year may need to suit family later, and the reverse is just as likely.
Choose the facade once the plan works
A freestanding flat is almost always seen alongside the main house, so the exterior should look like it belongs there rather than like something that arrived on a truck. Start with what already exists. The roof pitch. The window proportions. The color of the brick.
A Hamptons-style facade sits comfortably beside a weatherboard or clapboard house. Clean contemporary lines suit a rendered modern home. Classic detailing belongs next to traditional architecture. It is the same rule I use inside a house, that old things look better with new things next to them, only here the new thing should be a good neighbor and not a shout.
And you do not always have to trade layout for looks. Some builders let you browse granny flat designs and pair any floor plan with any facade, so the plan you need and the exterior you want can come together. Clarendon Homes, the New South Wales builder behind that catalogue, offers each of its plans in two specifications with a handful of facade styles on every one, which is exactly the kind of decision I would rather see made after the plan is settled, not before.
Where finish level matters most
Granny flats often come in more than one specification, a premium tier and a value-focused one. If the budget points you to the value option, spend where you will feel it every day.
Countertops and flooring get touched constantly and are hard to change later. Lighting sets the tone of a small home more than it does in a large one, because there is nowhere to hide from a bad ceiling fixture. Other finishes, hardware, paint, even cabinet fronts, are easy to upgrade down the track.
A value specification also responds beautifully to good furnishing, which is my territory. Size a rug to the seating area and it defines the living zone in an open plan without a single wall; our guide to choosing the right size area rug covers the arithmetic. In a flat this small I would go wool, with real color in it, because a rug here is doing the job that architecture does in a bigger house. That is the brief behind most of what we make at Kevin Francis Design. A pair of table lamps softens a room that is lit mainly from the ceiling. And per a rule I never break, tuck a hint of red in somewhere. A small house needs that jolt of life even more than a big one does. The rest of my thinking on furniture that works two jobs is in maximizing small spaces without making them feel small.
Walk through one before you commit
Granny flat floor plans are two-dimensional. They cannot show ceiling height, or how the light moves across a room at four in the afternoon, or how it feels to stand at the kitchen counter and look back toward the front door.
So if you can, walk through a display flat before you settle on a plan. Bring a tape measure and a list of the furniture that is actually moving in. Stand where the sofa would go. Open the wardrobe. Check the walking room around the bed. You will notice things in person that no plan or brochure can show you, which is the whole argument for visiting model homes before you build anything at all.
Granny flat floor plans: quick answers
What size granny flat floor plan should I choose?
Start with who will live there and what furniture they own, then look at the range. Ready-made plans commonly run from about 45 to 65 square meters (485 to 700 square feet). One occupant or a couple usually gets more from a one-bedroom plan with a larger living area; two bedrooms only pay off when the second room has a clear, regular use.
Is a one-bedroom or two-bedroom granny flat better?
At the same footprint, a one-bedroom plan gives the living and dining area more room, while a two-bedroom plan trades that space for flexibility. Choose two bedrooms for a grandchild who stays over, a study or a carer's room. If the second room would sit empty most of the year, give the space back to the living area.
Does the footprint shape of a granny flat matter?
Yes, more than most people expect. A near-square plan suits a tight backyard, while a wider, shallower plan gives you a long wall for windows. Orient that long wall toward the sun and the living area and bedroom can share the light and the view.
Should I pick the facade before the floor plan?
No. Settle the plan first, then choose a facade that complements the main house: Hamptons beside weatherboard, contemporary beside a rendered modern home, classic beside traditional architecture. Some builders let you pair any plan with any facade, so you rarely have to trade one for the other.
The actual point
Houses should be lived in, and every room should be enjoyed, and that goes double when there are only three or four of them. A granny flat is a small house for a person you care about. Give them a plan where the bed fits, the light lands where the sofa is, and the front door feels like their own. Then, and only then, argue about the cladding.
