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How to Build an Accessory Dwelling Unit (ADU) in Southern California

Aug 06, 2021
*The information below is for general use and is not legal advice.  Please verify and perform your own research on a specific property.
Designed to provide relief from California’s housing shortage, Senate Bill 1069 and Assembly Bill 2299 (collectively “SB 1069,” effective January 1, 2017) limit city authority to regulate accessory dwelling units (ADU).  Although, each city still has its own building code nuances and there are certain city limitations unique to the property location so it’s imperative that research and verification with local jurisdiction authority are highly recommended.

Generally, California homeowners (all Counties) now have an easier time building small second dwellings on their property. The law, SB 1069, gives owners of most single-family residences the option to construct ADU—informally known as back houses, granny flats, or in-law units—as long as they comply with certain guidelines.

ADU Interim Policy  Summary

  • ADU is permitted with a Site Plan Review if the property is zoned R-1, R-2, R-3, R-4, R-A, A-1 and A-2.
  • ADU is not allowed if intended for sale separate from the primary SFR.
  • A Certificate of Compliance may be required.
  • There is no minimum lot size as long as a legal SFR exists on site.
  • ADU can be an attached or detached unit.
  • ADU size: minimum (150 sq. ft.) and the maximum living area cannot exceed 1,200 sq. ft
    The maximum area for the attached ADU cannot exceed 50% of the existing primary residence.
  • Front yard setback: Title 22 requirements still apply for front yard setbacks.  Standard is 20 ft. and certain exception allows for 15 ft. or 10 ft. 
  • Setback from the rear and side property line: 5 ft.
  • Maximum height: refer to height requirements for the zone or Community Standards District (CSD), whichever is less restrictive.
  • ADU parking: one bedroom = 1 parking space, two or more bedrooms = 2 parking spaces.  Parking is waived if the ADU location is within 1/2 mile of a mass-transit or bus station.  There are other parking restrictions by city building codes.
For coastal areas, refer to the applicable Local Coastal Program at http://planning.lacounty.gov/coastal
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