3 bedroom ADU floor plans
Three bedrooms need about 900 sq ft or more, and 1,200 sq ft is the most California law allows for a detached ADU. These layouts put two or three bedrooms off a hall, with two baths and an open kitchen and living room.
1,100 sq ft 3 bedroom
| Kitchen | 15' x 8'-6" |
|---|---|
| Bath 1 | 6' x 8'-6" |
| Bath 2 | 6' x 8'-6" |
| Laundry closet | 5' x 8'-6" |
| Living | 14' x 18'-7" |
| Hall | 26'-7" x 3'-6" |
| Bedroom 1 | 8'-10" x 15'-1" |
| Bedroom 2 | 8'-10" x 15'-1" |
| Bedroom 3 | 8'-10" x 15'-1" |
$372K to $499K estimated build cost in Sacramento. Add your ZIP in the editor for your area.
More floor plans to start from
900 sq ft 3 bedroom
$319K to $428K estimated build cost in Sacramento. Add your ZIP in the editor for your area.
1,200 sq ft 3 bedroom
$399K to $535K estimated build cost in Sacramento. Add your ZIP in the editor for your area.
Is a 3 bedroom ADU worth it?
It houses a family or three renters, so it rents for more, but it costs the most to build and needs a lot big enough for about 1,000 sq ft plus setbacks. Check your lot before you fall for the plan.
At 900 sq ft the third bedroom is about 9 by 10 ft. At 1,200 sq ft the two main bedrooms reach about 13 by 15 ft.
California ADU size rules
- Detached ADU, largest
- Total floor area of a detached ADU can't exceed 1,200 sq ftGov. Code 66314(d)(5)
- What every city must allow
- A city can't use size, lot coverage or similar limits to block an ADU of at least 800 sq ft with 4 ft side and rear setbacksGov. Code 66321(b)(3)
- Attached ADU
- With an existing home, an attached ADU can't exceed 50 percent of the home's floor areaGov. Code 66314(d)(4)
- Junior ADU
- No more than 500 sq ft, inside the existing homeGov. Code 66333
Outside California, ADU size limits are set by each city or county. Your city's planning desk has the final word.
Will it fit your lot?
For homes in the California areas we cover, the free lot check reads your parcel, setbacks and local rules and shows the biggest unit that fits.
Check your lotQuestions
How big can a 3 bedroom ADU be?
In California a detached ADU can be up to 1,200 sq ft (Gov. Code 66314(d)(5)). Some cities set lower limits for attached units.
Do I need two bathrooms?
Not by law, but with three bedrooms almost every renter or family expects two. These layouts include two.
Last checked 2026-11-02. Costs are estimates priced at ZIP 95818, not bids. Floor plans are concept layouts; a licensed designer or architect prepares the plans your city approves.