Accessory Dwelling Units
The City of Santa Rosa allows development of an accessory dwelling unit (ADU) on any lot that allows a single-family or multifamily residential use and includes a proposed or existing dwelling, and allows the development of a junior ADU (JADU) on any lot developed with a single-family dwelling. The process to build an entirely new or to convert a portion of a property into an ADU can be complex. To better educate residents and prepare them for the plan submittal process, the City, in coordination with Napa Sonoma ADU, has created this page and asks those interested in developing an ADU on their lot to please start with the following:
- Review the ADU Process Map
- View the ADU Application Checklist
- Research the costs associated by trying the ADU Calculator
- Browse the Napa Sonoma ADU Gallery of Plans of prefabricated and site-built ADUs
- Note: under Option A (Pre-Reviewed Plans), click "Santa Rosa"
Before diving into building an ADU and meeting the requirements outlined below, it is important that any residential owner seek out the proper professional assistance and review the costs and resources required to build to add an ADU or JADU to an existing property. Once a residential property owner is ready to build and ADU on their lot, they can start reviewing the specific requirements and the application process below.
Requirements and Costs
Development standards (setbacks, height, etc)
The below tables provide general development standards for ADUs, depending on if they are in a single-family or multi-family zoning district. Please note, setback requirements may vary depending on the property’s zoning district. The guide to the City’s online mapping resources Opens a New Window. will help property owners determine their zoning district.
The development standards for a main residence by zoning district are depicted in Table 2-4 Opens a New Window. of the Zoning Code. Development standards, including setbacks have been simplified and are included in the current Ordinance. Other site constraints, such as easements may apply.
Please note that no development standards are applied that would prohibit at least an 800 square foot accessory dwelling unit that is at least 16 feet in height with four-foot side and four-foot rear setbacks to be constructed in compliance with all other local development standards.
Single-Family Zoning District Development Standards for ADUs
|ADU Internal Conversion||ADU Residential Addition||Detached 1-Story ADU||Detached 2-Story ADU|
|Front Setback||Sufficient for fire safety as determined by the Santa Rosa Fire Department||Same as detached one or two-story ADUs.||20 feet (4)||20 feet (4)|
|Side Setback||4 feet (2)||4 feet (3)|
|Side - Corner Setback||8 feet (2)||8 feet (3)|
|4 feet (2)||4 feet (3)|
|Height Limit||N/A||16 feet for one-story|
27 feet for two-story
|18 feet(5)||27 feet|
|Lot Coverage||N/A||40 % (1)|
|Maximum Square Footage|
Up to 45% of existing residential square footage or 1,200 square feet, whichever is less
Conversion of detached accessory structure:
Up to 1,200 square feet
|Up to 50% of existing residential square footage||Up to 1,200 square feet||Up to 1,200 square feet|
(1) Lot coverage standard cannot be applied if it would prohibit an 800 square foot ADU.
(2) May not apply in Hillside areas.
(3) Does not apply in Hillside areas.
(4) Allows development in the front setback if it would otherwise preclude development of an 800 sq ft ADU.
(5) See Zoning Code for exceptions
Multi-Family Zoning District Development Standards for ADUs
|ADU Internal Conversion||Detached 1-Story ADU|
|Front Setback||Sufficient for fire safety as determined by the Santa Rosa Fire Department.||10 ft provided a 1-story portion may project up to 6 ft into the setback and required stairs and landings may project up to 10 ft into the setback.|
|Side Setback||4 feet|
|Rear Setback||4 feet|
|Height Limit||N/A||18 feet|
|Lot Coverage||N/A||Same as Main Residential structures in primary zoning district.|
|Maximum Square Footage||Up to 1,200 square feet|
Up to 1,200 square feet
For any new detached ADU, one (1) additional parking space is required; however, no parking is required if one or more of the following exist:
- The ADU is 750 square feet or less or a studio unit; or
- The property is located in a historic preservation district; or
- The property is within 1/2 mile walking distance of a transit stop; or
- The ADU is part of the existing residence or within an existing accessory structure; or
- When on-street parking permits are required but not offered to the occupant of an ADU; or
- The property is within one block of a car-share vehicle.
For an internal conversion ADU or for a JADU, additional parking is not required.
An ADU that is detached from the proposed or existing single-family residence may include a detached garage.
Required Plans, Documents, Etc.
The following are the materials required for submittal of a building permit for both an ADU and Junior ADU (JADU). To begin the permit process with the city's planning materials, you will need to submit the following material:
- Site plan
- Floor plan
- Foundation plan
- Interior cross sections
- Construction details
- Elevations for new structures
- Deed Restriction as applicable (see the owner occupancy information below)
- Historic Resource Survey as applicable (see the historic preservation district information below)
See Frequently Asked Questions below to see size requirements for plans.
Building Division staff have prepared checklists for design professionals to ensure a complete submittal and minimize the need for plan revisions and related delays. They are linked below:
- Submittal Checklist for new detached ADUs
- Submittal Checklist for ADU interior conversions, additions, etc
Although State legislation exempts many ADUs from fire sprinklers, there are other instances where factors may still require the installation of fire sprinklers. Three of these factors are:
- Distance for fire response and access during emergency operations. Fire sprinklers may be required if any portion of the ADU is greater than 150 feet from Fire Department access (usually the street or road).
- Distance to fire suppression water supply. Fire sprinklers may be required If any portion of the ADU is greater than 400 feet from a water supply (typically a fire hydrant).
- ADU over a garage or carport. Fire sprinklers are required throughout a garage or carport with habitable space above. Garage or Carport AND an ADU require sprinklers.
NOTE: There may be additional factors that can require the installation of fire sprinklers.
Please be sure to check with Santa Rosa Fire to determine the need for fire sprinklers. Fire Department personnel are available at Planning & Economic Development on Tuesdays and Thursdays from 10:00AM to 12:00PM. The Fire Department Plan Review Division can be reached at (707) 543-3524 or [email protected]
For building a JADU, a Deed Restriction (also known as a Declaration of Restrictions of Occupancy) must be executed prior to occupancy of the unit.
Costs and Fees
Development Impact Fees
The amount to be paid for each of the following fees is identified in the table below:
- Capital Facilities fees
- Parks fees
Unit Size (Square Feet)
Percentage of Impact Fees Assessed
(the % of the fee to be paid by the applicant)
Utility Connections and Fees
Pursuant to Zoning Code Section 20-42.130(D)(3)(b), no new or separate utility connection, or related connection fee or capacity charge, will be required for the following ADUs:
- Internal conversions of existing space within a single-family residence or an accessory structure; or
- New ADUs (detached or attached) that are 750 square-feet or smaller.
After gathering the necessary plans and documents listed above, fill out a the forms listed below prior to your submittal:
- Building Permit Application
- For JADUs, a Declaration of Restrictions of Occupancy is required. Please review the link below for instructions regarding this process.
Submit your application, required plans and documents to [email protected]. A City of Santa Rosa employee will contact the you regarding the application fee payment once your application is received.
The application will be approved or denied within 60 days. If the application for an ADU/JADU is denied, the City will return in writing a full set of comments to the applicant with a list of items that are defective/deficient and a description of how the application can be remedied.
Eventually, the builder will schedule a final inspection through the City’s Automated Building Permit Inspection Request System. Once the ADU has passed, it's ready for move-in.
Frequently Asked Questions
The following are answers to frequently asked questions related to Accessory Dwelling Units (ADU) and Junior Accessory Dwelling Units (JADU):
What is an ADU?
An Accessory Dwelling Unit (ADU) is an attached or detached residential dwelling, located on the same parcel as an existing or proposed residential dwelling, that provides complete independent living facilities, including sleeping, cooking, bathing, and sanitation. An ADU can be located on any property where the zoning district allows a single-family or multifamily residential use that includes a proposed or existing dwelling.
What is a JADU?
A Junior ADU or JADU is unit that is no more than 500 square feet in size and contained entirely within a single-family residence which may include an attached garage. A JADU must include an efficiency kitchen, and may include separate sanitation facilities, or may share sanitation facilities with the existing residence. A Declaration of Restrictions of Occupancy is required for all JADUs. Please see the following link for instructions regarding this process: Instructions for Processing JADU Deed Restrictions
|Maximum Unit Size||Yes. Generally up to 1,200 square feet.(1)||Yes. 500-square foot maximum.|
|Bathroom||Yes.||No. Common sanitation allowed.|
|Parking||Depends. Parking may be eliminated and cannot be required under specified conditions.||No. Parking cannot be required.|
|Owner Occupancy||No.||Yes. Owner occupancy is required.|
|Ministerial Approval Process||Yes.||Yes.|
|Prohibition on Sale of ADU||Yes.||Yes.|
(1) No newly constructed attached ADU may contain habitable space in excess of 50% of the existing residential square footage .ens a New Window.
How do I obtain a permit for an existing Accessory Dwelling Unit?
Planning Department staff has prepared an informational handout to guide applicants through the process available HERE.
If my property is located in one of the City’s historic preservation districts, do I need to apply for a Landmark Alteration Permit?
No, a Landmark Alteration Permit is not required for ADUs or JADUs. However, through color, materials, and architectural features or a historic resource survey, you will be required to demonstrate that the proposed ADU is consistent with the time period of the residence’s construction and/or the adjacent historic structures.
Does my property need to be owner occupied?
The main residence on the site or the ADU are no longer required to be occupied by the property owner. However, the main residence or JADU are still required to be occupied by the property owner. Prior to occupancy of an JADU, the property owner is required to file with the County Recorder a deed restriction as out lined in Zoning Code Section 20-42.130(G) Opens a New Window. , which addresses owner occupancy of one of the units on site.
Instructions on processing a deed restriction are available HERE Opens a New Window. .
For more information on the deed restriction, please contact Angela Morgan at (707) 543-3465 or [email protected] Opens a New Window. .
Can I rent my ADU or JADU out as a vacation rental unit?
Neither an ADU nor a JADU can be rented for periods of less than 30 days.
If I convert my garage to an ADU, will I be required to replace those parking spaces on site?
No replacement off-street parking spaces are required when an ADU is created through the conversion or demolition of a garage, carport or covered parking structure.