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More Opportunities for Accessory Dwelling Units in Sonoma County

County to implement new State regulations
on January 1, 2020

Published:  December 24, 2019

Changes in State law related to accessory dwelling units (ADUs) will take effect January 1, 2020. These regulatory updates will remove minimum lot size requirements and reduce setback requirements, and private covenants (CC&Rs) may no longer prohibit ADUs on lots zoned for single family dwellings. These changes increase the number of properties eligible to have ADUs (also known as granny units, in-law units, and backyard cottages). However, properties must have adequate water and sewer or septic capacity in order to have an ADU.

“Accessory dwelling units provide property owners with the opportunity to generate income or house family members, while helping increase the number of housing units in the county,” said Board of Supervisors Chair David Rabbitt.

Permit Sonoma will implement the regulatory changes and work with property owners to permit new ADUs. Zoning permits will no longer be required for ADUs, though the process will still require building permits and any applicable related permits such as septic and grading permits.

Applicants will have three main steps to apply for a permit. First, the property owner should investigate the property’s septic suitability. Next, the applicant needs to find out whether the property has any additional requirements related to water, which will vary depending on the type of water service and location. Permit Sonoma’s website has a list of qualified septic consultants that are available to help you determine whether your property meets well and septic requirements for an ADU. After confirming that the property meets sanitation and water requirements, it’s time to submit a building permit application and any other related permits needed for the project. Permit Sonoma continues to offer reduced permitting fees for many ADUs.

Properties with an existing or proposed single family residence may qualify for one ADU and one Junior ADU (JADU), which is a smaller housing unit that can be created by converting an existing bedroom and adding a small efficiency kitchen.

ADUs cannot be used for vacation or short term rentals of less than 30 days. Some properties may be located in the “Z” (Accessory Dwelling Unit Exclusion) overlay zoning, which prohibits accessory dwelling units. If your property does not qualify for an ADU, it may qualify for a JADU. For more details on ADU requirements, step-by-step instructions for the application process, and frequently asked questions, please visit:

Contact Information

Permit Sonoma
2550 Ventura Avenue
Hearing Room
Santa Rosa, CA 95403
38.465074, -122.723705

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