Accessory Dwelling Units - ADUs

An Accessory Dwelling Unit (ADU) is a self-contained living unit that is usually smaller than the main home on the same property. It contains a kitchen, bathroom, and a place to sleep. They can be attached to the main home or a separate detached building. They can also take the form of a Junior Accessory Dwelling Unit (JADU), which is a unit up to 500 square feet and are converted from any existing floor space (bottom illustration).

Three different types of ADU

ADUs have been an effective way of incorporating smaller living units into the fabric of the community that are affordable to a wider range of income levels, including elderly family members.   


Due to the housing shortage in California, the State Legislature has passed significant housing related laws in the past three years. In 2019, the legislature passed over 20 bills intended to fast-track housing production – including accessory dwelling units (ADUs). 

Updates to State Law expands areas and conditions under which ADUs can be built. The ADU Handout reflects the regulations permitted by new state law, effective January 1, 2020. Be advised that this information is subject to change, as state guidelines and interpretations are typically issued after the enactment of new law.  


For ADU plans designed by a licensed professional or designer, please see Building’s Submittal Requirements for more information on what items needs to be provided to obtain a permit.


In August 2020, the Town will be launching a Permit-Ready Granny Unit Program to incentivize construction of quality ADUs that meet Danville’s design and neighborhood compatibility standards.  The program will offer a selection of pre-approved permit-ready ADU building plans that can be downloaded free-of-charge (detached units only).  Because these ADU plans have been pre-plan checked, they are eligible for expedited processing and lower building permit fees.  

Permit Ready Granny Units, Facilitating construction of quality accessory dwelling units in Danville

Permit-Ready Granny Unit Program Development Timeline

January 2020Release RFP/Q for Design Services
February 2020Select Design Consultants
March - April 2020ADU Plans: Conceptual Design (through 35%)
May - July 2020ADU Plans: Working Drawings (through 90%)
August 2020Program Launch

 Sign up for updates on the Permit-Ready ADU Program

For more information on the status of the program’s development, contact Guillermo Santolaya at (925) 314-3352 or 

  1. Example:
    Attached ADU
    Attached ADU
  1. Example:
    Detached ADU
    Detached ADU
  1. Example:
    Junior ADU
    Junior ADU