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New CA Accessory Dwelling Unit (ADU) Laws

California Accessory Dwelling Unit (ADU) Laws

The new California state law allows the addition of an Accessory dwelling unit (ADU) and/or one Junior Accessory Dwelling Unit (JADU) to those properties zoned for residential use which provides complete independent living facilities for one or more persons with an existing or proposed single-family dwelling (primary residence). A JADU means a complete independent dwelling that is no more than 500 sqft. in size and contained entirely within an existing or proposed single-family dwelling.

Guidelines for putting an Accessory Dwelling Unit on your property:

  • Can be attached to your primary residence or detached as long as it’s on the same property.
  • Can be rented out but can’t be sold separately from the primary residence.
  • Total sqft for an attached ADU can’t exceed 50% of the primary residence sq ft or more than 1200 sqft.
  • Total sqft for a detached ADU can’t exceed 1200 sqft.
  • Applicants must provide “floor area” for both units. These calculations must be made with the exterior dimensions of the outside walls.
  • Proposed garage attached to detached ADU shall not exceed the allowable combined square footages 25% greater than the main living area.
  • Only a garage can be attached to an ADU (You cannot add an addition).
  • An ADU could potentially be attached to an existing and permitted barn, shed, workshop, etc. As long as the existing footprint doesn’t change and it doesn’t have interior access to the remaining portions of the dwelling.
  • ADU shall provide one parking space. The parking space may be located within the setbacks and in an existing driveway as tandem parking. If demolition of the garage, carport, or covered parking structure occurs you do not need to replace parking spots.
  •  A parking spot is not required if the following applies:
    • ADU located within .5 miles of public transit
    • ADU located within architecturally and historically significant district

No setbacks are required if you have an existing permitted structure you will be converting to an ADU except for fire safety. 

The setbacks only apply to the added space above the accessory structure. An ADU can be constructed wholly or partly above the accessory structure, including extending beyond the accessory structure walls.

You must comply with these setbacks to be permitted to convert an existing structure to an ADU:

  • Detached ADU is limited to 24’ in height (except for multifamily complexes)
  • A setback of at least 4’ from the side and rear lot lines are required for an ADU that is being constructed above a permitted detached accessory structure. 
  • All newly constructed ADU’s must comply with the required front & exterior side yard setbacks and a minimum side and rear setback of 4’ (except required fire setbacks).
  • Garage, carport, patio, etc attached to ADU are subject to regular Zoning Ordinance regulations.

Junior ADU Requirements:

  • Can’t exceed 500 sqft.
  • Interior access connected to primary residence must be maintained as well as exterior access.
  • Shall include a full bathroom and an efficiency kitchen, requiring and limited to the following
    • Sink with maximum waste liner of 1.5 inches
    • Cooking facility not requiring more than 120 volts of electrical or natural/propane gas
    • Food prep counter 
    • Storage cabinets within ratio to unit
  • No additional parking is required

Use/Sale of ADU/JADU:

  • One ADU and One junior ADU permitted on lot with existing/proposed primary residence
  • ADU/JADU shall not be rented or used less than 30 days
  • Separate sale or ownership of an ADU is prohibited unless lot is subdivided creating a separate lot for each dwelling.
  • Junior ADU may be rented but NOT for sale separate from primary residence. You are required to live in one of the two units.

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