Accessory Dwelling Units

What is an Accessory Dwelling Unit (ADU)?

An Accessory Dwelling Unit (ADU) is an attached or detached residential unit that provides complete independent living facilities, including a bedroom, kitchen, and bathroom. A Junior Accessory Dwelling Unit can be no larger than 500 square feet and is contained entirely within an existing single-family home. A junior ADU may include its own bathroom, or share with the existing home.

Only one ADU or junior ADU is allowed on a lot, and only if the lot contains an existing or concurrently approved single-family home in the A, R-1, or HR zoning districts. The owner of the lot containing the ADU or junior ADU must also live on the lot. ADUs may be rented, but cannot be sold separately from the main home.

Permitting Process

The construction of an ADU or creation of a junior ADU are processed over-the-counter and without a public hearing, subject to approval of a building permit. However, ADUs that result in the following will require design review prior to building permit submittal:

  • A new multi-story main structure or multi-story accessory structure
  • The conversion of a single-story structure to a multi-story structure
  • A new structure over 18 feet in height or an existing structure that would exceed 18 feet in height as a result of the proposed construction
  • A project that increases the cumulative floor area of all structures on a site to more than 6,000 square feet
  • A project located within the Pmw, Pd, or Pdf areas as identified on the City's Ground Movement Potential Map

Legalization of Existing ADUs

ADUs and junior ADUs that were established within a permitted structure between August 18, 1984 and February 19, 2003 may apply for legalization with reduced development standards.

Summary of ADU Development Standards

  • The ADU and main home must use the same driveway to access the street
  • An ADU can have a maximum of 2 bedrooms  
Fire Sprinklers

Floor Area and Site Coverage

  • Attached or detached ADUs cannot exceed 1,200 square feet
  • An attached ADU also cannot exceed 50% of the existing or concurrently approved living area of the main home
  • If an ADU has a basement or an attic, that area is included as part of the total maximum floor area
  • Both the ADU and the main home count toward the total floor area and site coverage limits
  • A one-time 10% increase in site coverage and allowable floor area may be granted by the Community Development Director if the new ADU is deed restricted so it may only be rented to below market rate households
  • Height of the ADU must comply with the maximum height allowed in the zoning district
Lot Size
  • The minimum lot size must be 90% of the standard prescribed for the zoning district
  • One off-street parking space in a garage is required, in addition to the parking spaces required for the main homeThe garage requirement may be waived if an uncovered off-street parking space is provided and the ADU is deed restricted so it can only be rented to below market rate households
  • Setbacks must comply with those prescribed for the zoning district
  • A setback as low as 5 feet from the side and rear lot lines is allowed for an ADU constructed above an existing garage with legal non-conforming setbacks
  • No setback is required for an existing garage that is converted to an ADU or a portion of an ADU

More Information

You can view the Accessory Dwelling Unit Ordinance, learn more about design review, or contact the Planning Department. You can also download this information as a PDF.