Albert Lopez
Planning Director

Accessory Dwelling Units

Project Description

Accessory Dwelling Units (ADUs), also known as in-law units and casitas, are fully independent living quarters, created on properties which allow residential land use and are developed, or proposed for development, with a primary residence. ADUs are clearly accessory to a primary single-family or multi-family residence and are subordinate to it in size, location, and appearance. They may be created through new construction or through converting existing permitted interior space, or a carport, into an ADU. ADUs add to the local rental housing stock, can make home rental and ownership more affordable, allow opportunities for aging in place and may reduce greenhouse gas emissions when constructed in areas near public transit and services.

The County updated its ADU regulations in mid-2017 in response to changes to the state law which governs local ADU regulations. However, from 2017 through the present time, additional state-level changes have been adopted and are further under consideration, which has delayed the County's drafting of a new ADU ordinance. Once the state regulations stabilize, staff intends to resume ordinance drafting and to present new draft regulations to the public and decision makers.

In the meantime, staff has prepared interim ADU guidelines which are based on community input received by staff since January 2017 and on state laws that came into effect January 1, 2020, which now allow for a range of ADU types including Junior ADUs.

For Current ADU requirements, please refer to the information contained in the following links, noting that the ADU Handout and Government Code Section 65852.2 include the most current information available:

ADU Technical Assistance Program

The County of Alameda has a new ADU Technical Assistance program (HelloADU) that can help homeowners through every step of the ADU process. To learn more about the program and how to apply, please visit You can also email with any questions that you may have.

Links & Resources

Once the draft ADU regulations are available, they will posted on this webpage along with public meeting schedule. Please check this webpage frequently if you are interested in the regulations update. Information concerning the last regulations update may be obtained by accessing the archived files (link below).

Contact for general ADU information:

Permit Center / Zoning Counter

399 Elmhurst Street, Suite 141

Hayward, CA 94544

Phone 510.670.5400

Contact for ADU regulations update status information:

Rodrigo Orduña

Alameda County Planning Department

224 West Winton Avenue, Suite 111

Hayward, CA 94544

Phone: (510) 670-5400

Send an email

Past code update meetings/materials may be found in the Archive page (link)