800 sq ft ADU floor plan
A detached two-bedroom ADU in a 40 × 20 ft rectangle, exactly the 800 sq ft California guarantees on most lots: two bedrooms and the bath at one end, an open kitchen, dining and living room at the other. Open it free and fit it to your yard.
- Size
- 800 sq ft
- Bedrooms
- 2
- Bathrooms
- 1
- Floors
- 1
The layout
A long, narrow footprint is what fits behind most houses, so the plan runs in a line. The front door is on the end wall, straight into the living room, which spans the full 20 ft depth with windows front and back. Next to it the kitchen and the dining area share the middle of the building, joined to the living room and to each other by wide openings: 376.6 sq ft that reads as one room.
A 4 ft hall leads from the dining area to the private end. Off it are the bath (9 × 6 ft on the wall grid, with a tub), a stacked laundry closet with a 42 in opening, and the two bedrooms. Bedroom 1 is the corner room with windows on two walls; bedroom 2 is smaller and still has two windows, so both have an escape opening.
Room sizes
| Room | Net area (ft²) | Net area (m²) |
|---|---|---|
| Living room | 175.4 | 16.30 |
| Kitchen | 88.5 | 8.22 |
| Dining | 112.7 | 10.47 |
| Bedroom 1 | 115.7 | 10.75 |
| Bedroom 2 | 93.2 | 8.66 |
| Bath | 45.4 | 4.22 |
| Laundry | 21.4 | 1.99 |
| Hall | 48.1 | 4.46 |
| Total, net | 700.5 | 65.08 |
The 800 sq ft is measured to the outside faces of the walls (40 × 20 ft is 800.1 sq ft), which is how ADU size caps are normally written; the rooms inside add up to 700.5 sq ft. Bedroom 1 takes a queen bed with nightstands; bedroom 2, at 93.2 sq ft, takes a full or queen bed, or a desk and a twin.
Who it suits
- Homeowners adding a rental. Two bedrooms rent to a couple with a child or two roommates, which a studio cannot.
- Family on the same lot. An aging parent, an adult child or a caregiver gets a full home with its own door, laundry and kitchen.
- Back yards with room to spare. At 20 ft deep, plus a 4 ft rear setback and some space from the main house, it needs roughly 30 ft of yard depth.
Make it yours
- Fit your buildable area. Drag the outside walls to the space left after your setbacks; the room areas update as you go. Add plot size with your lot's width and depth to see the ADU against the lot lines, with its Plot coverage.
- Trade the tub for a shower. Select the tub and replace it with a shower from the Library.
- Make bedroom 2 an office. Select it and pick Furnish as, then office; it undoes in one step.
- Check it. The Review panel flags a room under 70 sq ft or 7 ft across, a ceiling under the minimum and a bedroom without an escape opening, while you are still moving walls.
- Hand it on. Export a DXF for your designer's CAD, or a scaled Print set PDF for a first meeting with the planning department.
Questions
Can I build an 800 sq ft ADU in California?
On most single-family lots, yes: a city cannot use lot coverage, floor area ratio, open space or front setbacks to stop a detached ADU of up to 800 sq ft with 4 ft side and rear setbacks. Height limits and other local rules still apply; California ADU size limits has the details.
What about other states?
Several states now require cities to allow ADUs, with different size caps and parking rules. ADU laws by state lists them, with a guide per state.
Is 800 sq ft measured inside or outside?
Usually outside: size caps count the floor area to the outside of the walls. This plan is 800.1 sq ft that way and 700.5 sq ft of net room area inside.
Can it have a loft or a second floor?
You can add one with Add floor, but height limits for detached ADUs are often low, so check your city's limit first; California ADU size limits covers the state's 16 to 25 ft range.