Accessory Dwelling Units (ADUs)

What is an Accessory Dwelling Unit?

An Accessory Dwelling Unit (ADU) is an attached or detached residential dwelling unit that provides complete, independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking, sanitation, and parking, and is located on a lot with a proposed or existing dwelling. They may be permitted in any residential zoning district, subject to approval by the Community Development Department through the Building Permit plan review process. The Building Permit Fees are based on the size of the unit and the proposed scope of work to create the unit.

Ordinance Update

Recent changes to State law requires cities to update their ADU regulations to streamline the development of ADUs. City Council adopted updates to the ADU Ordinance at its meeting on September 27, 2022. The updates become effective on October 27, 2022. The adopted Ordinance can be viewed here.

Pre-Approved ADU Plan Program

Updated information regarding pre-approved ADUs can be found here, or by visiting the link in the red column on the left side of this page.

The cities of Arroyo Grande, Atascadero, Grover Beach, and Morro Bay obtained grant funding as joint applicant to hire a consultant and create a pre-approved ADU plan program. The goal of this joint effort is to expedite the ADU permitting process and encourage the construction of accessory units to support our regional housing goals.  This joint effort for Regional Pre-Approved Accessory Dwelling Unit stock plans responds to local conditions and design themes and will be available for use by the cities of Atascadero, Arroyo Grande, Grover Beach, and Morro Bay. The benefits of pre-approved ADU plans include:

  • Saving applicant pre-construction design time and money by providing a selection of pre-approved stock plans in a variety of sizes and styles 
  • Streamlining the City construction plan check review process (plans will be pre-reviewed and approved. Only site specific plans will require review)
  • Boosting production and development of accessory units that can help each City maintain housing stock that is affordable by design

The Planning Commission provided feedback to the consultant on the six (6) preliminary design themes. The staff report for that item can be viewed here. Conceptual plans for the pre-approved ADUs can be found here

For more information about the program, please contact Andrew Perez, Planning Manager at or (805) 473-5425.

Additional Resources: