Accessory Dwelling Units (ADUs, In-law Units)


Since the early 1900’s, the Western familial structure has moved away from multi-generational living. With people living longer and healthier lives, the financial burdens of aging first generation parents has become a concern to most families.

In most recent times, the in-law unit concept has begun resuming its practicality. The inclusion of first generation parents living with the family helps financially as the income and expenses of two households can be consolidated and shared. In addition, senior citizens can continue to maintain their self-sufficiency and productivity while living within these arrangements.

City Policy

Accessory Dwelling  Units (ADUs), or in-law units, are allowed on single family properties in all single family residential and multiple family residential zones. The intent of City policy is to provide opportunity for the creation of small rental housing units that meet the housing needs of individuals and families, particularly those of low and moderate income. Furthermore, City policy allows more efficient use of the City's existing stock of dwellings; provides economic support for resident families of limited income; provides rental housing units for persons who are elderly or disabled; and protects property values and the integrity and character of single family neighborhoods by ensuring that second family residential units are architecturally compatible with the primary structure and neighborhood.

ADU applications do not require a public hearing and are reviewed through the Building Permit process.  Requests for ADUs are ministerial permit applications in accordance with the Government Code. The permit will be approved if the proposed unit complies with the standards and requirements outlined in the City's ordinance.

Zoning Ordinance Update

In recognition of the extreme need for affordable rental housing in California, recent changes to state law establish new rules in regards to “Accessory Dwelling Units” (ADUs), previously known as “Second Family Dwelling Units,” and commonly known as in-law units or granny flats. 

The City’s Zoning Ordinance was most recently modified in 2019 (effective March 8, 2019), to include new state law regulations. For more information, contact the Duty Planner at or at 925-256-3558.


Contact the utility districts listed below for more information regarding connection fees for your proposed project.

Contra Costa Water District, Customer Service: (925) 688-8044

East Bay Municipal Utility District, New Business Office: (510) 287-1008

Central Contra Costa Sanitary District, Permit Team: 925-229-7371

Summary Requirements and Forms

ADU Regulations Guide

Instructions to apply for ADUs

For more information, contact the Duty Planner at or at 925-256-3558