ADUs are allowed in the City of Rohnert Park with a Certificate of Zoning Compliance and building permits. Applicants are encouraged to speak with staff about application requirements prior to submitting the Zoning and Land Use Application for the Certificate of Zoning Compliance. The steps to build your ADU and receive approval from the City are described below. Some applicants work with a professional architect, designer or engineer through all or some the steps described below while others may choose to complete these steps on their own.

Graphic of planning permit process

Contact City of Rohnert Park Development Services to discuss requirements and ask questions: (707) 588-2236 or
Download a PDF of the Planning Permit Process diagram.

Step 1: Understand Your Zoning Requirements

First, you will need to find your lot size, zoning district, and maximum allowed site coverage, as well as other development standards.

The City’s zoning district regulations determine what types of ADUs are allowed on a property. Find your property on the City’s Zoning Map to determine your property’s zoning district. If you can’t find your zoning district using that map, find your assessor’s parcel number (APN). You can usually find your APN on property tax files or land deed. Alternatively, you can look up your APN on the City’s geographic information system (GIS) webpage or call the City Planning Department for help.

Once you have your APN, you can search the City’s GIS webpage to find your zoning district. Then, check Zoning and Allowed ADU Types to see what types of ADUs are allowed in your district. See ADU Development Standards, for diagrams and key details on each of the ADU types in Zoning and Allowed ADU Types.

  Residential Districts  Mixed-Use Districts
  R-R /
  • Attached ADU
    • New Construction
    • Conversion of Part of Existing Home or Attached Garage
  • Detached ADU
    • New Construction
    • Conversion of All or Part of Existing Accessory Structure
Yes Yes Yes No No No No
  • Attached ADU
    • Conversion of Existing Non-Habitable Area of Building
  • Detached ADU
    • New Construction
    • Conversion of All or Part of Existing Accessory Structure
No No No Yes Yes Yes No
Junior ADU (JADU)
  • Conversion of Part of Existing Home or Attached Garage
Yes Yes Yes No No No No

Note: If your zoning district is not included in this table, that district does not permit ADUs. 

R-R = Rural Residential District
R-E = Estate Residential District
R-L = Residential-Low Density District
R-M = Residential-Medium Density District 

R-H = Residential-High Density District
DRT-H = Downtown Residential-High Density District
MU = Mixed Use District
DTM-U = Downtown Mixed-Use District 

Download a PDF of the Zoning and Allowed ADU Types table.


Step 2: Determine Your Allowed and Available Site Coverage

To check your allowed and available site coverage, you will need to find the lot size of your property. Similar to the previous step, you can find this information using your APN (found on property tax files, land deed, the City’s GIS webpage, or by calling the City Planning Department). Field verification will be required. Look up your lot size on:

Next, find out how much of your property is allowed to be covered by buildings by looking at the requirements for your zoning district in the City’s Municipal Code, Section 17.10.020. This is typically measured as a percentage of the property’s total square footage and called the “maximum lot coverage” or “maximum floor area ratio requirement.” Multiply your maximum site coverage percentage by your lot size in square feet using the equation below. Then, find how much of your lot is currently covered by a building, or your “current lot coverage”, by looking at your home deed or websites such as Zillow. You can also calculate your floor area by measuring your home’s gross floor area as defined in City’s Municipal Code, Section 17.04.030.

Once you find your existing floor area, the difference between your current lot coverage and the maximum allowed lot coverage will tell you how much space you have to develop a detached or attached ADU, using the equation below.

Maximum Lot Coverage × Lot Size - Total Current Building Square Footage = Square Footage Available for ADU Construction

For example, if your maximum site coverage is 50 percent and your lot size is 5,000 square feet, then the total square footage of buildings cannot be greater than 2,500 square feet. However, if your ADU will be less than 800 square feet, it will not count toward your maximum allowed site coverage and the calculation does not need to be done. In addition, this does not apply to conversion ADUs or JADUs since you will not change your existing building footprint.

Step 3: Determine Your ADU Design, Project Goals and Budget

ADUs can be created by building a new detached structure or converting interior space within an existing single-family home, garage, accessory structure, or multifamily structure. JADUs can only be created by converting interior space of an existing single-family home. City regulations allow for ADUs up to 1,000 square feet depending on the type. The zoning of the property and size of the primary dwelling may be determining factors in the maximum size of your ADU. The ADU Development Standards specifies the standards by type.

You will want to sketch your property and ideas for the location and size of your new ADU. Various online tools for sketching floor plans and site plans are also available. Create a list of your goals for the project and design ideas. When you meet with an architect, designer, or contractor, you want to be as prepared as possible with your list of needs and requirements for the project. Some fire safety and adaptability features are required by State law, as enforced by the City’s Building and Residential Codes. You may also want to consider incorporating additional accessibility features if you anticipate older relatives or someone with a disability living there. You will also want to know approximately how much you can spend before hiring a professional. See Resources for financing options.

Step 4: Complete a Zoning and Land Use Application for a Certificate of Zoning Compliance

Compile the necessary components of your Zoning and Land Use Application for the Certificate of Zoning Compliance with the Planning Division.
Download the Zoning and Land Use Application.
Go to Permitting to Occupancy page for ADUs.

Step 5: Apply for Building Permits

Once approvals are received for your Certificate of Zoning Compliance, submit your application for building permits.

You may need to hire design professionals to assist in the preparation and construction of an ADU. Consider what type of construction is best for you. Building the ADU on site or bringing a prefabricated or manufactured home to your property will impact the type of professional you hire. The American Institute of Architects can provide a list of licensed architects and engineers in your area.

If your ADU is constructed using prescriptive construction methods found in the California Residential Code, then the plans do not require a licensed design professional. If your ADU deviates from prescriptive methods and follows performance-based standards, then the plans submitted to the City in the Certificate of Zoning Compliance and Building Permit application packages must be stamped by a licensed architect or engineer. Depending on your situation and City requirements, you may also need to hire other specialized professionals.

ADU Navigation Links

Planning Division

City of Rohnert Park Development Services – Planning Division
130 Avram Ave.
Rohnert Park, CA 94928
Phone: (707) 588-2231
Email: [email protected]

Building Division

City of Rohnert Park Development Services – Building Division
130 Avram Ave.
Rohnert Park, CA 94928
Phone: (707) 588-2240
Email: [email protected]