An accessory dwelling unit sounds small, and the square footage is. The requirements are not. An ADU is a complete, self-contained home — it just has to do everything a home does in a fraction of the space.
Which is why the considered ones feel generous, and the rushed ones feel like a shed with a kitchen.
A small home is still a whole home
The plan has to account for kitchen, bath, sleeping, storage, access, utilities, and privacy. Making all of that feel roomy in a compact footprint is the actual design problem, and it rewards careful planning.
The rules change block to block
Setbacks, height, parking, maximum size, and utility requirements vary by city and county, and they move often. Early code review is what keeps a project from getting sent back at submittal or quietly redesigned twice.
Utilities and site are the hidden line item
Water, sewer, power, grading, and access are frequently where an ADU budget is really decided. A tidy floor plan can still sit on a demanding site — and knowing that early keeps everyone’s expectations honest.
Build it to belong
The best ADUs relate to the main house, keep usable yard, and read as part of the property. Sometimes a shared roofline, or a considered path between the two, is what turns two buildings into one home.
And how you will actually use it — family, guests, aging in place, rental income — should drive the design, not a generic layout.
