Attachment A: Redline of proposed ADU ordinance code changes § 17.42.170. Accessory dwelling units/junior accessory dwelling units.
This section establishes procedures and development standards for accessory dwelling units ("ADUs") and junior accessory dwelling units ("JADUs"), where allowed by Chapter 17.22 (Allowable Land Uses), and in compliance with this title and California Government Code Sections 66310 through 66342 ("state ADU law"), as may be amended from time to time.
A. Review. ADUs/JADUs that are consistent with the standards of state ADU law and this title, as modified by state ADU law and this section, shall be subject to a ministerial, nondiscretionary city review process in conformance with state ADU law. ADUs that are not consistent with the standards of state ADU law may be subject to a discretionary design review process by the city.
The city shall not deny an application for a permit to create an ADU due to the correction of nonconforming zoning conditions, building code violations, or unpermitted structures that do not present a threat to public health and safety and are not affected by the construction of the ADU.
B. Development Standards.
1. Application of State ADU Law. Each ADU/JADU shall be consistent with all development standards identified in state ADU law except as modified by this section.
2. Land Use and Zoning Conformance. Each ADU/JADU shall meet all development standards of the zoning district in which it is located and other standards set forth in this title, except as modified by this section or by state ADU law.
a. ADUs/JADUs shall not be included in density calculations or unit count to determine the number of housing units per gross acre for residential or mixed-use properties and shall not be included in site coverage calculations for a lot.
b. A certificate of occupancy for an ADU shall not be issued before that of the primary dwelling.
3. Location. Generally, ADUs/JADUs should be located to the side and/or rear of the primary structure on the site. Exceptions may be allowed in limited circumstances in which no other location is feasible to build an ADU due to the presence of mature, healthy trees; infrastructure; utility, access, or other easements; natural resources, hillsides, wetlands, or riparian features; existing accessory structures of a permanent nature including garages, carports, site-built custom sheds or greenhouses, or workshops/studios; in-ground swimming pools or spas; or other similar features as determined by the community development director. No ADU of more than eight hundred square feet of interior li space gross floor area shall be located within the front setback or street side setback of a lot.
4. 2. Parking. One parking space shall be required for each ADU, except when an exemption is provided by state ADU law. No parking is required for JADUs.
35. Size and Lot Coverage. ADUs shall be subject to the following requirements related to size:
a. ADUs on single-family lots and attached ADUs on multifamily lots less than one-half acre (twenty-one thousand seven hundred eighty square feet) in size shall be limited to the following maximum sizes:
Less than two
bedrooms
Eight hundred fifty
square feet of interior
livable spacegross
floor area
Two or more
bedrooms
One thousand square
feet of interior livable
spacegross floor area
b. ADUs on single-family lots and attached ADUs on multifamily lots less than one-half acre in size may exceed the above maximum sizes subject to approval of discretionary design review by the planning commission.
c. In no case shall any detached ADU on a single-family lot or attached ADU on a multifamily lot exceed one thousand two hundred square feet of interior livable spacein size. d. The interior livable spacegross floor area of an attached ADU shall not exceed fifty percent of the existing interior livable space gross floor area of the primary residence. Notwithstanding the existing interior livable space gross floor area of the primary residence, an ADU may contain at least eight hundred square feet of interior livable spacegross floor area. e. The minimum allowable interior livable space gross floor area of an ADU shall be the minimum size permitted by the California Building Code, but in no case shall it preclude a minimum-sized efficiency unit.
f. No ADU of more than eight hundred square feet of interior livable space shall be located within the front setback or street side setback of a lot. ga. ADUs/JADUs shall not be included in density calculations or unit count to determine the number of housing units per gross acre for residential or mixed-use properties and shall not be included in site coverage calculations for a lot.
46. Occupancy, Rental, and Sale.
a. A certificate of occupancy for an ADU shall not be issued before that of the primary dwelling, except in a situation where all of the following requirements are met:
i..The primary dwelling was substantially damaged or destroyed by an event referenced in a state of emergency proclamation issued by the California Governor on or after February 1, 2025 that is applicable to Sonoma County;
ii. The ADU is not attached to the primary dwelling; and iii. The ADU has been issued construction permits and has passed all required inspections.
b. Owner-occupancy of an ADU, JADU, or the or its primary another dwelling on the property is not required, with the exception that if a JADU shares sanitation facilities with the primary dwelling, the owner must reside in either the primary dwelling or the JADU. Either the JADU or the primary dwelling associated with a JADU must be owner-occupied, unless the owner is a government agency, land trust, or housing organization. cb. Any ADU/JADU may be rented separately from the primary dwelling, for a minimum rental term of thirty days.
dc. An ADU may be sold separately from the primary dwelling, in accordance with state ADU law.
57. Height and Setbacks.
a. All ADUs shall comply with the primary structure height and setback requirements of the underlying zoning district with the exception of those described below:
Type of ADU Minimum Setbacks Maximum height*
Attached Four feet side and rear Twenty-five feet
Detached Four feet side and rear Eighteen feet
No setback shall be required for an legally existing living space, garage, or accessory structure which is fully or partially converted to an ADU, or for a structure constructed in the same location and to the same dimensions as a legally existing living area, garage, or accessory structure which is fully or partially converted to an ADU. The maximum height for such structures shall be the greater of the existing height of the structure prior to conversion to an ADU, or the applicable height set forth in Section
17.42.170(B)(57)(a).
*Any ADU shall be allowed up to two additional feet in height to accommodate a roof pitch that is consistent with that of the primary dwelling. b. No ADU shall exceed a height of two stories, with the exception of an interior ADU constructed fully within an existing dwelling or structure.
C. Rental. ADUs/JADUs must be rented for a minimum term of thirty days.
CD. Termination of Permit and Use. At his/her discretion, the community development director or his/her designee may grant an owner's request to terminate an ADU/JADU. As a condition of termination, the director or his/her designee shall require the owner to make modifications to the property to comply with current building code requirements, and remove the kitchen through a building permit process as required by the city's building and fire codes.