ADU rules in San Diego County, CA — also called accessory dwelling unit regulations or granny flat ordinances — cover setbacks, owner-occupancy, parking, and permit requirements.
San Diego County allows Accessory Dwelling Units (ADUs) on residential properties in unincorporated areas per state law and the County ADU Handbook. Detached ADUs up to 1,200 sq ft. Must maintain 4-foot side/rear setbacks. ADUs up to 800 sq ft are exempt from lot coverage limits.
California state law (Government Code §65852.2) and the County of San Diego allow ADUs on single-family and multi-family residential properties in unincorporated areas. Detached ADUs can be up to 1,200 sq ft. Attached ADUs can be up to 50% of the existing living area or 1,200 sq ft, whichever is less. Both attached and detached ADUs must maintain at least 4-foot side and rear setbacks. Front setbacks follow the underlying zone, but detached ADUs may be in the front setback if lot constraints prevent other placement. ADUs up to 800 sq ft are exempt from lot coverage calculations. Detached ADUs 16 feet or under can be at the property line; taller ones need 4-foot setbacks. Minimum 6-foot separation from other structures required. Fire-rated construction needed if eave spacing is less than 10 feet. Building permits required through County PDS.
Unpermitted ADUs may result in code enforcement, fines, and required demolition or retroactive permitting.
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See how San Diego County's adu rules rules stack up against other locations.
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