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Accessory Dwelling Units
Accessory Dwelling Units (ADU)
Accessory Dwelling Units (ADUs) are known by many names: granny flats, in-law units, backyard cottages, secondary units and more. No matter what you call them, ADUs are an innovative, affordable, effective option for adding much-needed housing.
State Guidance for ADUs
As of January 1, 2019, homeowners who created accessory dwelling units (ADUs) without the required building permits may have the opportunity to bring their ADUs into compliance.
Learn more about the State Law and Guidance for ADUs
Planning Approvals
- Accessory Dwelling Unit (AD) Permit Application Form (PDF)
- ADU Application Submittal Checklist (PDF)
- ADU Application Processing Guidelines (PDF)
Building Permit Requirements
- Application for Permit (PDF) **All contractors must have an active business license with Contra Costa County if doing work in Unincorporated areas of the County. Visit the County Business License link for additional information on how to apply for a license.
Required Forms for Owner / Builder Permit Applications
Forms below are required for submission prior to permit issuance
- Authorization of Agent to Act on Property Owner’s Behalf (PDF)
- Owner-Builder Acknowledgement and Verification of Information (PDF)
If you are thinking about making any improvements to your home or parcel, and you have a septic system, you need to have your plans reviewed by Environmental Health.
Learn more about Septic System permitting.
Background information
Contra Costa County has developed a program for homeowners who created accessory dwelling units (ADUs) without the required building permits an opportunity to bring their ADUs into compliance, without paying the penalty fees that would typically be associated with previously unpermitted construction.
This program will be available until July 1, 2021.
ADU Incentive Program (PDF)
Types of ADU and Legalization Process
Eligibility
- ADU must be existing. It may not be under construction.
- ADUs with active code enforcement actions are not eligible for the program.
Process
Schedule an Initial Meeting
The Initial Meeting is an opportunity to meet with Planning, Building, and Inspection staff to better understand what permits and fees are required to for your existing ADU.
Online meeting request form
Call 925-674-7200
Preparing for the meeting
The more information you provide at the meeting, the better staff will be able to assist you. Please bring
- Photos
- Site plan (drawing of all property lines and structures on the property
- Floor plan of the ADU
After the Meeting
At the end of the meeting, you can decide to withdraw from the program. County staff will not keep any record of the initial meeting.
If you choose to move forward, you will not be assessed any penalty fees associated with unpermitted uses or construction.
Next Steps
Planning Approvals
- Accessory Dwelling Unit (AD) Permit Application Form (PDF)
- ADU Application Submittal Checklist (PDF)
- ADU Development Standards (PDF)
Building Permit Requirements
- Application for Permit (PDF) **All contractors must have an active business license with Contra Costa County if doing work in Unincorporated areas of the County. Visit the County Business License link for additional information on how to apply for a license.
Required Forms for Owner / Builder Permit Applications
Forms below are required for submission prior to permit issuance
- Authorization of Agent to Act on Property Owner's Behalf (PDF)
- Owner-Builder Acknowledgement and Verification of Information (PDF)
If you are thinking about making any improvements to your home or parcel, and you have a septic system, you need to have your plans reviewed by Environmental Health.
Learn more about Septic System permitting.