ADU Ready: Pre-Reviewed Accessory Dwelling Unit Plans

Licensed professionals can submit ADU designs to Permit Sonoma for pre-review. Approved designs are listed in the ADU Design Gallery. Homeowners can browse the gallery and contact a listed vendor to obtain a plan package.

Applicants may work with a professional or follow owner-builder requirements to integrate the selected ADU plan into a project-specific package for submission with a building permit application. Applicants are responsible for licensing fees and any plan-use restrictions established by vendors.

Once a complete building permit application is submitted and initial fees are paid, Permit Sonoma reviews the application within 30 days. The review evaluates zoning consistency, fire code compliance, water supply adequacy, wastewater disposal capacity, and other site-specific requirements.

If revisions are needed, applicants will be notified. When all requirements are satisfied, final fees are assessed and the building permit is issued. Construction may then begin, and after all required inspections are successfully completed, a certificate of occupancy is granted.

Project Applicants

Individuals or entities planning to build an ADU using pre-reviewed plans. Applicants may work with a design team to adapt the plans to their property and site conditions.

Plan Vendors

Licensed professionals who submit plans for inclusion in the ADU Design Gallery, including:

• Designers of stick-built ADUs
• Producers of factory-built or manufactured ADUs

Using pre-reviewed ADU plans reduces the amount of design and review work required by providing a base template for the ADU itself. However, site-specific conditions and constraints must still be addressed by the applicant.

Examples include foundation requirements, wastewater disposal, water service, fire-safe standards, access, and zoning requirements. Because these factors vary from property to property, plans listed in the ADU Design Gallery are considered pre-reviewed rather than pre-approved.

ADU Ready streamlining applies to new detached ADU construction using unmodified pre-reviewed plans. Modifications to these plans may require additional review, fees, and processing time.

Vendors listed in the ADU Design Gallery may also provide design inspiration or custom design services for projects that do not utilize the ADU Ready program.

Projects located in the Coastal Zone (parcels with a CC zoning designation) may use the ADU Ready program but are subject to different development standards and permitting requirements than inland ADUs.

Refer to Coastal Zone ADU requirements for additional information.

• Review Standards for ADUs.
• Use the Zoning and Land Use Map Viewer to identify requirements that apply to your property.
• Visit the Permit Center to meet with staff from various divisions such as Planning, Fire Prevention, Engineering and Construction.

• Browse the ADU Design Gallery and select a design that meets your site-specific requirements.
• Though the ADU itself will be pre-reviewed for building code compliance, it must still meet zoning and construction standards for your specific site.
• Contact the listed plan vendor to obtain plan sets and discuss any licensing or plan-use fees. Available designs may be stick-built, factory-built, or manufactured.
• Record the reference number for your selected design and include it with your permit application.

• Integrate the selected ADU plan into your project site design and compile a complete application package.
• An ADU Ready-specific application checklist is coming soon. In the meantime, refer to the 9-4-5 Stock Plan Procedure and Building an ADU Step-by-Step.
• Once you have ensured your project complies with standards and your application package is complete, submit a building permit with plan check application through our Permits Online portal.