ADU Ready Design Submissions

Once your ADU plans have been approved as pre-reviewed, basic plan attributes and your contact information will be added to Permit Sonoma’s Pre-reviewed ADU Design Gallery for the remaining duration of the code cycle it was approved under. You will become referenced as a “plan vendor” and project applicants looking to build ADUs under the ADU-Ready program may contact you to obtain a pre-reviewed ADU plan package.

Project applicants are responsible for licensing fees and limitations on use as required by plan vendors. 

Pre-reviewed ADU plans may not stand alone and must be integrated with a specific site and project scope. Project applicants and their teams are responsible for this integration and the procurement of a complete building permit application. Plan vendors may choose to offer services to assist in this process.

Once plans are approved as pre-reviewed, licensing fees for the same pre-reviewed ADU package may be sold repeatedly until the end of the code cycle.

Vendors’ plans and contact information will be listed in our online gallery to be perused by potential ADU project applicants. Applicants may reach out to purchase a pre-reviewed ADU plan package, but they may also be looking for help with a custom ADU project outside of the ADU Ready program.

Plan vendors will submit stock plan (STK) applications for the pre-review of accessory dwelling unit (ADU) designs.  

Stick Built Designs

• Select "ADU Ready Stick Built" for type under Record Informtion when prompted.
• Review 9-4-5 Stock Plan Procedure (Part A) for submittal requirments and procedures. Other helpful links:
  • BPC-065 2025 CALGreen Checklist Residential New Construction
  • CNI-033R Statement of Special Inspection
  • BPC-002 Residential Plan Checklist
• Additionally, include the following in your application to be posted in the ADU Design Gallery:
  • Design name
  • Link(s) to your design or firm page
  • Contact information customers can use to purchase plans
  • High-resolution photo(s) or rendering(s) of your design, licensed for Permit Sonoma's use in perpetuity t
• Pay fees for review and listing.

Factory Built and Manufactured Designs

• Select "ADU REady MH/FB" for type under Record Information when prompted.
• Factory Built and Manufactured Homes are subject to regulations set by the California Department of Housing and Community Development (HCD) and the U.S. Department of Housing and Urban Development (HUD).
• Include the following in your application:
  • Plans approved by an HCD or HUD-approved Design Approval Agency (DAA) or Design Approval Primary Inspection Agency (DAPIA) with stamps where appropriate
  • Model number (issued by the DAA or DAPIA)
• Additionally, include the following in your application to be posted in the ADU Design Gallery:
  • Design name.
  • Link(s) to your design or firm page.
  • Contact information customers can use to purchase plans.
  • High-resolution photo(s) or rendering(s) of your design, licedned for Permit Sonoma's use in perpetuity
• Pay fees for review and listing.

ADUs should be designed to meet all adopted codes such as those for building, energy, and fire safety. A partial list is referenced in BPC-002 Residential Plan Checklist.

• ADUs must meet minimum building code standards for living space and must have permanent provisions for living, sleeping, eating, cooking, and sanitation.

An ADU plan submitted for pre-review may be of any size though certain sizes may be desirable for those looking to minimize fees or maximize the size of their ADU. Some relevant cutoffs for attached AUDs are listed below:

• Based on Interior Square Footage.
  • Inland:
    • ≤ 1200 square feet – All new construction detached ADUs on single-family lots
    • ≤ 800 square feet – ADUs may override certain setback requirements
    • ≤ 750 square feet – ADUs are exempt from park and traffic impact fees
    • ≤ 500 square feet – ADUs are exempt from school fees
  • Coastal Zone:
    • ≤ 1000 square feet – ADUs with a recorded affordable housing agreement
    • ≤ 840 square feet – All other ADUs (non-Affordable)
• Based on Height
  • Inland: ≤ 35 feet
  • Coastal Zone: ≤ 16 feet
• Bedrooms: Many residences in the unincorporated county rely on well and septic systems. The quantity of additional bedrooms allowed on a property will depend on water availability and waste system capacity. To accommodate this a variety of 1-, 2-, and 3-bedroom designs would ideally be hosted in the pre-reviewed ADU plan gallery. See Policy 1-4-1 Definition of a Bedroom.  

Pre-reviewed plans are only maintained in our ADU Design Gallery until the end of the triennial California Build Standards Code cycle they were approved under. If you wish to renew your listing, submit a new STK application referencing the STK number assigned to the original listing and highlighting updates made for any new applicable code requirements. Otherwise, designs will automatically expire and be removed at the end of each cycle.  

Plan vendors should notify Permit Sonoma when featured designs are no longer offered.  

To request removal of your designs from our ADU Design Gallery, submit your request via email to PermitSonoma@sonomacounty.gov.
Be sure to include the following information in your request:

• The STK number (reference number in the ADU Design Gallery) 
• Your name and company name.
• The name of the listed design
• Proof of design ownership
• Reason for removal request

Plans will be removed from the gallery within 30 days of receiving a complete removal request