Accessory Dwelling Units

The State of California supports development of Accessory Dwelling Units (ADUs) and Junior Accessory Dwelling Units (JADUs), also known as granny or in-law units, as a meaningful housing solution. ADUs and JADUs are now permitted by-right on any residentially zoned lot in Petaluma. Please review the information below to learn more about our local requirements for developing an ADU or JADU. 

ADU 1 White Back
ADU 2 White Back
ADU 3 Building Your ADU

Step 1: Design Your ADU/JADU

  • Key local development standards are described below. Complete development standards for ADUs and JADUs are in Section 7.030 of the Petaluma Implementing Zoning Ordinance (IZO).  The development standards described below are Planning development standards regulating site location, building height, and building size.
  • A Building Permit is required for development of an ADU/JADU.  Our Building Division provides an ADU Checklist which details specific application requirements.
  • The Napa Sonoma ADU Center has a number of helpful resources, including an ADU Calculator, ADU Workbook, and free, customized ADU Feasibility Consults 
  • Consider working with a design professional to help you plan and budget for a new ADU or JADU. 
  • City staff can further assist you with questions related to permit requirements and associated fees. To contact Petaluma Planning staff, please follow the link here to find the different ways to receive assistance from staff:

Development Standards 

City of Petaluma - Development Standards for ADUs
Setback ADU or JADU Internal Conversion (1) Attached ADU - Residential Addition Detached ADU
Side Setback N/A 4 feet 4 feet
Rear Setback N/A 4 feet 4 feet
Maximum Height N/A 16 feet (2) 16 feet (3)
Maximum Square Footage 500 square feet if JADU Up to 50% of existing residential square footage (4) Up to 1,000 square feet (5)
  1. No change to existing building footprint. 
  2. If outside of the Zoning district’s Primary Structure Setback requirements, an ADU could be the height allowed of the Primary Structure.
  3. If a rear setback of 5 feet is maintained, could be up to 21 feet.
  4. Does not apply to ADUs that have a total living area no greater than 800 square feet, are not taller than 16 feet, and provide minimum four-foot side & rear-yard setbacks. Up to 1,000 square feet.
  5. Measured as total living area. “Living area” is the interior habitable area of the accessory unit including basements and attics but not including garages. Living area shall be measured from the interior side of the exterior walls of the building.

Important Things to Note While Designing Your ADU or JADU

  • Open Space. Parcels on which accessory dwellings over 800 square feet are built are required to have a minimum of 100 square feet of useable open space available for use by occupants of the unit, independent of the primary residence’s requirement.  
  • Fire Sprinklers and Fire Attenuation. Accessory dwelling units shall not be required to provide fire sprinklers if fire sprinklers are not required for the primary residence. 
  • Short Term Vacation Rentals. All accessory dwelling units permitted after September 7, 2017, shall only be rented for a term of more than 30 days. No accessory dwelling units permitted after September 7, 2017, shall be permitted as a short-term vacation rental under Section 7.110. 
  • Owner Occupancy Requirements for JADUs. The owner of a parcel with a single-family dwelling and a proposed junior accessory dwelling unit shall occupy as a principal residence either the primary dwelling or the accessory dwelling. 

Step 2: Submit required applications 

Step 3: Build your ADU/JADU! 

  • During construction, Building Division will conduct several inspections to ensure that construction complies with the local Building Code. 
  • The final step in the building permitting process is to issue your Certificate of Occupancy. 


Frequently Asked Questions

A Junior ADU or JADU is unit that is no more than 500 square feet in size and contained entirely within the walls of a single-family residence and may be constructed within an attached garage. A JADU is required to have an efficiency kitchen which complies with any applicable requirements of the Building Code, and includes a cooking facility with appliances, and a food preparation counter and storage cabinets that are reasonable to size of the unit.  JADU’s may share a bathroom with the primary residence.

The City of Petaluma has recently transitioned to an all-digital Online Permit Hub. You will need to register for an account and upload all application materials to this online portal.

To apply online, please visit the following link to the City’s Online Permit Hub:

New parking is not required for Accessory Dwelling Units in Petaluma.

All ADUs require a separate address, whereas JADUs are not required to obtain a separate address. New addresses are created via an Address Assignment from the Planning Division. Address Assignments applications are accepted online here, and must be completed prior to building permit issuance. JADU applicants must file an Address Assignment application if a separate address is desired.

All ADUs less than 750 square feet, are exempt from development impact fees. All other ADUs must pay a fee, which as required by the new state legislation, must be based on the units size relationship to its primary residence. More information about development impact fees is available on the City’s Planning Applications and Handouts page, which is linked here: 

 No, Site Plan and Architectural Review (SPAR) is not required for new ADUs and JADUs. However, specific criteria need to be met if the subject property is in a historic district. See IZO § 7.030 (O.) for complete design requirements for ADUs on designated landmark sites or within a designated historic district 

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