Accessory Structures in San Diego County, CA (2026)

5 county-level rules, plus city-specific rules for 10 cities in San Diego County, California.

Verified from official government sources

Note: These county rules apply to unincorporated areas of San Diego County. If you live within an incorporated city, that city's own rules apply — see the city list below.

ADU Rules

In unincorporated San Diego County, one ADU and one JADU may be added to a lot with an existing or proposed single-family dwelling. A detached ADU may not exceed 1,200 sq ft; an attached ADU is capped at 50% of the main home, up to 1,200 sq ft. Rules implement California ADU law.

San Diego County Accessory Dwelling Unit (ADU) Rules

Few Restrictions

Full ordinance details →Official source ↗

Shed Rules

Detached storage buildings, workshops, and hobby sheds are accessory uses under Zoning Ordinance Section 6156.g. The combined area of all such structures is capped at 1,000 sq ft (or 25% of the home, whichever is greater) on lots under one acre, with larger allowances on bigger parcels.

San Diego County Shed and Storage Building Rules

Some Restrictions

Full ordinance details →Official source ↗

Garage Conversions

Converting an existing permitted garage or accessory structure into an ADU is allowed in unincorporated San Diego County. No setbacks or additional development standards apply to the conversion of existing permitted space, and demolished or converted garage parking does not have to be replaced for an ADU.

San Diego County Garage Conversion Rules

Few Restrictions

Full ordinance details →Official source ↗

Carport Rules

Carports are accessory structures under Zoning Ordinance Section 6156. Attached carports fall under Section 6156.a and detached carports under Section 6156.g, with combined-area caps of 1,000 sq ft (or 25% of the home) on lots under one acre and larger allowances on bigger parcels.

San Diego County Carport Rules

Some Restrictions

Full ordinance details →Official source ↗

Tiny Homes

Unincorporated San Diego County has no separate 'tiny home' ordinance. A tiny home on a foundation is regulated as an ADU under Zoning Ordinance Section 6156 (max 1,200 sq ft detached), while a tiny home on wheels is treated as a trailer coach/recreational vehicle and may not be used as a permanent dwelling outside permitted situations.