New state law should ease some restrictions on construction

Changes in state law that take effect Jan. 1 are expected to increase the number of properties eligible for accessory dwelling units (ADUs, also known as granny units, in-law units, and backyard cottages). The 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. 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, according to Permit Sonoma. 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 who are available to help 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 offers 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 by 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.

For more details, visit

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