Studio ADU Floor Plans

A typical single-car garage is about 12 by 20, and this is what fits inside one once you have insulated the walls and infilled the garage door. Two hundred and forty square feet, all of it usable.

What works: the bath and kitchen share the north wall, which on most garages is the wall closest to the house. That matters more here than on any other plan, because the cost of a garage conversion is decided almost entirely by how far the new drain has to travel to reach the existing sewer lateral.

What to watch: the garage door opening is on the south wall and it is usually the widest opening in the building. Infilling it is your chance to put in a proper glazed wall, and skipping that is why so many converted garages read as converted garages. Also measure your ceiling height before anything else. Under about 7 feet 6 inches to the framing and this project does not happen.

Older single garages are often narrower and deeper than modern ones, around 10 by 24. Same 240 square feet, a harder shape to work with.

What works: at ten feet of interior width there is exactly one sensible arrangement, and this is it. Wet rooms at the far end, one long living space, and no attempt to create a hallway that would eat a third of the floor.

What to watch: ten feet is narrow enough that furniture placement becomes a real design question rather than an afterthought. Draw the bed and the sofa on the plan before you commit. And check the wall construction: many old narrow garages sit on a curb with rotted sill plates, which is a structural repair before it is a conversion.

This is the arrangement I draw first whenever someone says the word studio. Twenty by twenty, bath and kitchen sharing a single wet wall across the north side, and everything else left as one 240 square foot room you can arrange however you like.

What works: one plumbing wall. The bath and the kitchen sink sit back to back, so there is a single drain run leaving the building instead of two. On a detached unit that is the difference between one trench and one very awkward conversation with your plumber.

What to watch: at 20 feet square, the sleeping area has no walls around it, so think about where the bed goes before you place the windows. I have seen this exact footprint ruined by a window centred on the only wall the bed fits against.

Same 400 square feet, stretched to 16 by 25. This is the version for a side yard rather than a back yard, and the shape is doing the work: a narrow footprint clears side setbacks on lots where the square version simply will not fit.

What works: the long living space takes daylight from three sides, which matters more at this size than any amount of finish budget. A 400 square foot room that is dark reads as small. The same room with windows on two walls does not.

What to watch: the walk from the front door to the bath passes through the whole living space. That is fine when you live alone and irritating the moment you have a guest on the sofa. If that bothers you, Layout A keeps the circulation shorter.

Five hundred square feet exactly, and that number is not an aesthetic choice. It is the ceiling California puts on a junior ADU, so this is the biggest version of this plan that can still take the JADU route if it sits inside an existing house.

What works: the extra hundred feet over Layout A all lands in the living space, which is where you feel it. A 340 square foot main room takes a proper sofa, a dining table and a bed without any of the three touching.

What to watch: if you are building this as a detached unit, the 500 foot line stops mattering and you should ask whether 600 buys you a real bedroom wall. Often it does, for less money than the finish upgrade you were also considering.