ADU Basics

ADU Basics

California recently changed laws relaxing the availability and cost of permits for Auxiliary Dwelling Units. Assembly Bill 68 had a profound impact on ADU regulations and it was signed into law in October 2019 by Governor Gavin Newsom.

Accessory Dwelling Units can take one of three forms:

  1. Detached: Unit is separated from the primary structure.
  2. Attached: Unit is attached to the primary structure. So the accessory dwelling unit would be built onto an existing home, but maintain its own kitchen, bath, and private entrance.
  3. Repurposed Existing: Space within a primary residence that is converted into an independent living unit, like a garage conversion.

Other relevant information:

  • Any single-family residence that is zoned for Single Family residential can build an accessory dwelling unit. Some multi-family zoned lots can build an ADU, but check before you start.
  • The accessory dwelling unit cannot be sold separately from the main home, but is always rentable.
  • Fire sprinklers are not required for an attached accessory dwelling unit unless they are required for the primary residence. (This saves homeowners around 7K!)
  • The lot doesn’t have any code violations. This must be resolved prior to permits.
  • An attached accessory dwelling unit cannot exceed 50% of the primary residence, up to 1,200 square feet. For example, if your existing house in 2,500 sq. ft., the attached ADU cannot exceed 1,200 sq. ft. in size.
  • Any existing legal structure can be converted into an accessory dwelling unit. This is great for homeowners looking to maximize their garage! In fact, an existing permitted garage doesn’t have to comply with any additional setback requirements.
  • Fees must be proportional to the structure being built. San Diego just passed the waiver of development and impact fees saving San Diegans an average of $17,000!
  • Short-term vacation rentals are not allowed in the ADU.
  • Both the primary and the ADU are rentable because owner occupancy is not a requirement.

Setback Requirements for Accessory Dwelling Unit Regulations in San Diego

  • There are no setback requirements when converting an existing structure, like a garage!
  • An ADU attached to the primary residence must comply with the required main building setbacks.  
  • A 2-story ADU can encroach on the rear and side setbacks.
  • There are not requirements for how far an ADU has to be from the main dwelling.

Parking Requirements for Accessory Dwelling Unit Regulations in San Diego

  • A new ADU shall provide .5 parking space per 1 bedroom. These spaces may be provided as tandem parking and can be located in the driveway.
  • Homeowners must add one parking spot if the garage is converted, but it can be located anywhere on the property, and it can also be in a driveway or tandem.
  • Parking spaces must be 8 ft. X 18 ft. Compact parking is not allowed.
  • Parking is NOT required if you live within half a mile of public transit. (orange in the map below designates public transit zones)
  • Parking is NOT required if you live in a historic district.
  • Parking is NOT required if the accessory dwelling unit is part of an existing primary residence. (For example, you are converting an existing basement or another part of your home).
  • Parking is NOT required if you live within one block of a car share area.

For a complete list of ADU Zoning Requirements in San Diego please click here.