The City of Sonoma is excited to announce the launch of its Pre-Reviewed ADU Plans Program, an initiative designed to make Accessory Dwelling Unit (ADU) construction easier, faster, and more cost-effective for homeowners and designers.
ADUs, also known as in-law units or granny flats, provide a valuable opportunity to add affordable housing options while generating rental income for property owners. To support this effort, the Pre-Reviewed ADU Plans Program allows designers to submit ADU plans for pre-approval for compliance with California Building Code. Once approved, property owners can use these plans to reduce plan check timelines and construction costs, making it easier to build ADUs throughout Sonoma.
How the Program Works
- For Designers: Architects and designers can submit their ADU plans for pre-approval by including a completed Pre-Approved ADU Plans Checklist with a Building Permit application. Plan check fees apply, and an initial deposit is required.
- For Homeowners: Property owners can select from a list of pre-reviewed ADU plans, saving time and money in the approval process. While each design firm may have its own associated fees, using these plans generally results in lower plan check fees and a faster permitting process.
Additionally, Sonoma is part of a countywide collaboration, meaning pre-approved plans may be eligible for use in multiple Sonoma County jurisdictions.
Available Pre-Reviewed ADU Plans
The City currently has pre-approved plans ranging from 500 to 1,200 square feet, with more designs being added as they are submitted. Some key highlights include:
- 500-749 sq. ft. ADUs (Exempt from impact fees but subject to school fees)
- 750-1,200 sq. ft. ADUs (Subject to both school and impact fees)
Plans vary in size and layout, from cozy one-bedroom cottages to spacious two-bedroom homes. Additional site-specific engineering and soils analysis may be required.
Why Consider an ADU?
- Affordable Housing Solution – ADUs provide additional rental opportunities within the community.
- Faster Approvals – Pre-reviewed plans streamline the permitting process.
- Lower Costs – Reduced plan check fees help keep project expenses manageable.
- Flexible Housing Options – Great for multigenerational living, guest space, or rental income.
For more information on the Pre-Reviewed ADU Plans Program, including available plans and designer submission details, visit Sonoma’s ADU Program Page or contact the City of Sonoma Planning Department.