Accessory Dwelling Unit Regulations

What is aN ACCESSORY DWELLING UNIT?

An accessory dwelling unit (ADU) is a second living unit located on the same lot as a single-family home in the R1 (Single-Family) Zoning district. They are also referred to as granny units, in-law units, or companion units. ADU's typically contain a bathroom, one or two bedrooms, a kitchen and, sometimes, a garage or carport. ADU's provide housing opportunities within single-family neighborhoods and are either attached to or separated from the main home. 

State Accessory Dwelling Unit Regulations

In September 2016, Governor Brown signed Senate Bill (SB) 1069 and Assembly Bill (AB) 2299, amending Section 65852.2 of the Government Code. Effective January 1, 2017, this amendment provided exceptions to the amount of required parking, allowed conversion of existing garages, reduced building setbacks, and limited fire sprinkler and water meter requirements for all ADUs. These amendments reduce barriers and streamline approval of ADU's in all California cities. See the Senate Bill and California Department of Housing and Community Development (HCD) Memo summarizing the law for more information.

In 2019, the Governor signed into law new regulations that impact ADU regulations statewide, which became effective January 1, 2020. The Environmental Planning Commission recommended City Council approve the Draft ADU regulations on March 4, 2020 at a public hearing. The City Council did not review the Draft ADU regulations on April 28, 2020; the item was returned to City staff for further review.

The Draft ADU Regulations were reviewed by the Environmental Planning Commission at a Public Hearing on September 16, 2020, where they recommended City Council to approve the text amendments. The ADU regulations are tentatively scheduled to be reviewed by the City Council at a public hearing on October 27, 2020 at 6:30 p.m., or as soon thereafter. The meeting agenda, staff report, and associated documents, including information on participating in the meeting or providing public comment, will be posted the Friday prior to the meeting date at mountainview.legistar.com

To receive email notifications of upcoming meetings on the ADU regulations, please create an account (or login to an existing account) at MyMV and select My MV Home - General - Companion Unit Updates.

  • Draft ADU Regulations
  • While no Planning permit is required, all new ADUs require building permits. The City encourages all applicants to review preliminary ADU plans with Planning and Building staff to ensure the project meets all requirements, prior to preparing detailed construction plans. 

For questions regarding the ADU regulations, please contact the Planning Division by phone at (650) 903-6306 or by email.

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