Accessory Dwelling Units & Junior Accessory Dwelling Units

Accessory Dwelling Units (ADUs) and Junior Accessory Dwelling Units (JADUs) are an inexpensive way to create smaller, more affordable rental housing units that may provide revenue streams for property owners, while increasing the availability of rental housing in the county.

Note: Changes in State law related to accessory dwelling units took effect January 1, 2020. As a result, local rules no longer apply. See the pages on this website for more information on the current standards for ADUs and JADUs

What's the difference between an ADU, a JADU, and a guest house?

Updated ADU and JADU Ordinance Effective October 14, 2021

On September 14, 2021, the Sonoma County Board of Supervisors approved changes to the Zoning Code that updated ADU and JADU regulations. This page will be updated before the effective date of October 14, 2021. 

Read adopted ordinance (Ordinance No. 6352)


Accessory Dwelling Unit (ADU)

Accessory dwelling units (ADUs) are small dwelling units up to 1,200 square feet.

An ADU is a small permanent home that may be established in addition to the main dwelling on a parcel zoned for residential use. ADUs may be attached or detached from the main dwelling.

Most residential zoning districts allow one ADU unless the property has the "Z" (Accessory Dwelling Unit Exclusion) overlay zoning district.

ADUs can be rented for long-term occupancy, but they cannot be used as vacation rentals.

Read More about Accessory Dwelling Units

Junior Accessory Dwelling Unit (JADU)

Junior Accessory Dwelling Units (JADUs) are a very small living unit (up to 500 square feet) created out of space within an existing single family home.

A JADU is created by adding a small kitchen and exterior door to space in an existing single-family dwelling. It may include a bathroom or may share a bathroom with the primary dwelling.

JADUs are allowed in every zoning district that allows a single-family dwelling.

JADUs can be rented for long-term occupancy, but cannot be used as vacation rentals.

Read More about Junior Accessory Dwelling Units

Contact Information

Contact Planning by Phone
Monday – Friday
10:00 AM – 12:00 PM
1:00 PM – 3:00 PM
2550 Ventura Avenue
Santa Rosa, CA 95403
38.465074, -122.723705


ADU Calculator

Junior Unit

Try this new online tool to help estimate the costs, returns, and benefits associated with building an ADU.

Fire Prevention & ADUs

Fire Prevention Information on Accessory Dwelling Units

Fire Prevention and HazMat

Requirements for ADUs including fire access, sprinklers, and more.

Sonoma County Housing Authority

Resources for Property Owners

Hands forming house

If you plan to rent your ADU, consider participating in the Housing Authority's Housing Choice Voucher program and being a part of the solution to the County's affordable housing crisis.

State ADU Law

California Department of Housing and Community Development's web site describing state laws and regulations about Accessory Dwelling Units.

View State Web Site