Accessory Units & Junior 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 you, while increasing the availability of rental housing in the county.

Changes in State law related to accessory dwelling units took effect January 1, 2020

Current regulations based on State law are summarized on the Accessory Dwelling Unit page. As of January 1, 2020, the County's ADU ordinance no longer applies.

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Accessory Dwelling Unit

Accessory dwelling units (ADUs) are backyard cottages 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 there is a "Z" (Accessory Dwelling Unit Exclusion) overlay zoning on the property..

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

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.

It’s created by adding an efficiency kitchen (see "Efficiency kitchen" Sec. 26-02-140) and exterior door to an existing, legal bedroom. It may include a bathroom or may share a bathroom with the house.

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

Can be rented for long-term occupancy, but cannot be used as a vacation rental.

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