ADU rules in San Diego, CA

Yes. Every ADU needs a building permit and a final inspection before anyone lives in it.

Rules last checked by a person on October 19, 2026. Guidance only; confirm with San Diego before you build.

City and state limits

Side setback (max a city can require)	4 ftNo setback at all for an ADU inside an existing structure or rebuilt in the same footprint.
Rear setback (max a city can require)	4 ft
Detached ADU height (minimum a city must allow)	16 ft; 18 ft within 1/2 mile of major transit (+2 ft for matching roof pitch) or on a lot with a multistory multifamily building
Attached ADU height (minimum a city must allow)	25 ft or the house's height limit, whichever is lower
Size a city must allow	At least 850 sq ft (1 bedroom) or 1,000 sq ft (2+ bedrooms)
Guaranteed regardless of lot coverage or FAR	800 sq ft with 4 ft side and rear setbacks
Junior ADU	Up to 500 sq ft inside the house
Parking	No more than 1 space per unit or bedroom; none within 1/2 mile walk of transit
Owner occupancy	Cannot be required for an ADU (JADUs with shared sanitation excepted)
Impact fees	None for an ADU of 750 sq ft or less

Call 811 at least a few days before you dig footings or post holes. Utility locating is free.
HOA covenants and deed restrictions can be stricter than city rules. Check yours before you build.

HCD Accessory Dwelling Unit Handbook (March 2026). Checked 2026-10-19.
A setback of no more than four feet from the side and rear lot lines shall be required for an attached or detached ADU (Gov. Code, 66314(d)(7)).
44 CFR 59.1, definition of development (NFIP). Checked 2026-10-19.
Development means any man-made change to improved or unimproved real estate, including but not limited to buildings or other structures...
44 CFR 60.3, floodplain management criteria. Checked 2026-10-19.
Require permits for all proposed construction or other development in the community...