Accessory Dwelling Units

What is an ADU?

An Accessory Dwelling Unit (ADU) is an attached or detached residential dwelling, located on the same parcel as an existing single-family dwelling, that provides complete independent living facilities, including sleeping, cooking, bathing, and sanitation.

As of January 1, 2017, Santa Rosa Zoning Code Section 20-42.130 and that portion of 20-36.040 (parking) pertaining to accessory dwelling units are superseded by state law. The new laws create specifc exceptions for parking, setbacks, and some utility fees. City staff have prepared guidance for ADU development until City ordinances implementing state law are enacted. Click the link below to view the interim guidance document.

Proposed Zoning Code Revisions

The City of Santa Rosa is preparing an amendment to the Zoning Code to comply with the new law and to incentivize the construction of ADUs. In January, a community meeting was announced through social media and City outreach groups such as the Community Advisory Board. The community meeting was held on February 8, 2017, with over 100 attendees. City staff continues to collect feedback and evaluate policy options. 

Revision Summary

  • Parking requirements for ADUs will be waived if the ADU is an internal conversion of an existing structure, or within a half-mile of a bus stop, or in a historic preservation district.
  • With some exceptions, setback requirements for ADUs will be waived if the ADU is an internal conversion of an existing structure or built over an existing garage.
  • The requirement for an owner occupancy deed restriction for ADUs would be removed.
  •  A minimum 30-day rental period will be placed on all ADUs.
  • Utility fee and connection requirements for ADUs will be waived if the ADU is an internal conversion of an existing structure.
  • The maximum square footage of an ADU will be increased to 1,200 square feet, and the limitation of only one bedroom will be removed.
  • The requirement for a permanent foundation will also be removed.
  • Standards will be provided for the development of ADUs in hillside areas and historic preservation districts.
  • Addition of a category for Junior Accessory Dwelling Units (JADUs).
  • A fee reduction program is being evaluated to address Affordable Units by design or under contract. 

Detailed Revisions

There have been two minor changes to the proposed Code revisions since their initial publication in February 2017. The maximum square footage for detached structures was revised to match the maximum allowed by the State of 1,200 square feet. The maximum square footage for attached structures is 1,200 square feet or 50% of the existing residence, whichever is less. For example, an existing 1,000 square foot residence could build an attached ADU up to a 500 square feet in area, or a detached ADU up to 1,200 square feet in area elsewhere on the property.

A new provision added to the proposed Code changes is that two-story detached ADUs continue to be subject to the setbacks for the primary residence, and one-story detached ADUs only need to meet less restrictive accessory structure setbacks instead of primary residence setbacks.

Through the public comment process, the primary feedback received by staff was that cost of construction for ADUs, including the City permit fees, was prohibitive. The State regulation provides limited relief from water and sewer fees specifically for internal conversions of existing structures.

To facilitate construction of ADUs, City staff is considering expanding fee relief to specific types of ADUs as part of an ongoing fee analysis. Staff are proposing to reduce fees for ADUs that do not exceed 750 square feet, or are subject to an affordability contract, or are internal conversions to existing residential space.

It is important to note that any fee reductions would be part of a separate action that would need approval by the City Council.

City staff took the proposed revisions to the Planning Commission on June 22nd, 2017, where the amended proposal was unanimously approved. A City Council hearing date has not yet been scheduled. When the hearing date is set, noticing and meeting materials will be made available through the City’s legislative portal linked below.

Future meetings will be announced via email. 

Public Comment

Please send your comments on the following topics being considered for revision:

  • Parking
  • Setbacks and Other Development Standards
  • Dwelling Size
  • Number of Bedrooms
  • Owner Occupancy Deed Restrictions
  • Short-term Rental Restrictions
  • Utility Fees

The resolution containing the proposed zoning code revisions approved by the planning commission is linked below. To be placed on the notification list or send questions and comments contact Eric Gage, the project planner,at or 707.543.4351. 



pcoming Meetings:

On June 22th at the regularly scheduled Planning Commission meeting, staff presented the proposed Accessory Dwelling Unit Zoning Code Text Amendment to the Commission for consideration and recommendation to the City Council. The amended resolution was unanimously approved. A City Council hearing date has not yet been set. The Planning Commission agenda and hearing materials are available through the City’s online legislative calendar at

  1. Eric Gage

    City Planner
    Phone: 707-543-4351