Attachment 4
Accessory Dwelling Unit Standards
DRAFT Updated 11.19.24
The following standards apply to development of accessory dwelling units (ADUs) and junior accessory dwelling units (JADUs) in Cotati, as set forth in California Government Code Sections 66310-66342, as may be amended from time to time, (“State ADU Law”) and Cotati Municipal Code (CMC) Chapter 17.22 and Section 17.42.170.
See last page for key definitions.
A. General Requirements--All ADUs/JADUs
1. Location. ADUs and JADUs are allowed on any property where a single-family dwelling or multifamily dwelling(s) exists or are proposed to be developed along with the ADU/JADU(s).
2. Review and Permitting.
a. A permit application for an ADU/JADU that conforms to all required standards shall be ministerially approved within sixty days from the date the City receives a complete application if there is an existing single-family or multifamily dwelling on the lot. If the application is submitted with an application to create a new single-family or multifamily primary dwelling(s) on the lot, the applications will be considered in tandem according to the required timeline for the primary unit(s), although the review of the ADU/JADU will be ministerial.
b. 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.
c. A demolition permit for a detached garage that is to be replaced with an ADU shall be reviewed with the application for the ADU and issued at the same time as the ADU building permit. The applicant shall not be required to provide written notice or signage posting for such demolition.
d. A certificate of occupancy for an ADU shall not be issued before that of the primary dwelling.
3. Number of ADUs/JADUs Allowed.
a. Single-Family Lots: One detached ADU; one JADU; and/or one ADU that is located fully within the existing or proposed primary dwelling, or within an existing accessory structure with a maximum expansion of such accessory structure of one hundred fifty feet strictly for Attachment 4
the purposes of accommodating ingress and egress, may be developed on a residentially zoned parcel with a proposed or existing single-family dwelling. b. Multifamily Lots:
i. A maximum of eight detached ADUs may be located on a lot with an existing multifamily dwelling(s), although the number of such ADUs shall not exceed the number of existing units on the lot. Not more than two detached ADUs may be located on a lot with a proposed multifamily dwelling.
ii. Multiple ADUs may be developed within portions of existing multifamily structures that are not used as livable space, including storage rooms, attics, basements, or garages, if each unit complies with state building standards for dwellings. The number of such ADUs is limited to twenty-five percent of the existing number of units on the property, except that at least one is allowed.
4. Occupancy, Rental, and Sale.
a. Owner-occupancy of an ADU or its primary dwelling is not required. 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. b. Any ADU/JADU may be rented separately from the primary dwelling, for a minimum rental term of 30 days.
c. An ADU may be sold separately from the primary dwelling, in accordance with State ADU Law.
5. Fire and Safety
a. Street addresses shall be assigned to all ADUs to assist in emergency response. Address creation for a JADU may be required depending on the configuration of the unit, and subject to the Fire Marshal’s recommendation.
b. ADUs/JADUs are not required to install fire sprinklers if they are not required for the primary dwelling. Construction of an ADU/JADU shall not cause fire sprinkler installation to be required for the primary dwelling.
6. Impact Fees and Utilities
a. ADUs of seven hundred fifty square feet or less and JADUs shall not be subject to development impact fees. ADUs larger than seven hundred fifty square feet shall be subject to impact fees charged proportionately in relation to the square footage of the primary dwelling unit.
b. ADUs/JADUs are not required to install new or separate utility connections directly between the ADU and the utility, unless the ADU is sold separately from the primary dwelling subject to state ADU law.
Attachment 4
c. ADUs/JADUs that are constructed fully within the space of an existing single-family dwelling shall not require a new or separate utility connection or be subject to a related connection fee or capacity charge, unless sold separately from the primary unit subject to state ADU law.
d. ADUs/JADUs shall not be subject to connection fees or capacity charges for utilities, including sewer and water, unless constructed with a new single-family dwelling or sold separately from the primary dwelling subject to state ADU law.
7. Nonconforming and Unpermitted Units. 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 shall not be grounds for denying a permit for an ADU.
B. Development Standards – ADUs
1. Land Use and Zoning Conformance. Each ADU shall meet all development standards of the zoning district in which it is located and other standards set forth in the CMC, except as modified by State ADU Law and CMC Section 17.42.170.
2. Permanent Foundation. A permanent foundation shall be required for all ADUs.
3. Separate Entry. All ADUs shall contain a separate entrance, independent of the primary dwelling. No passageway shall be required in conjunction with the construction of an accessory dwelling unit.
4. Kitchen and Bathroom. An ADU may have a partial kitchen and bathroom, if the ADU meets the requirements of the state health and safety code for an “efficiency unit.” Otherwise, a full kitchen and bathroom are required.
5. Location.
a. 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 of up to 800 square feet on the property due to the presence of mature, healthy trees; utility 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 features, as determined by the community development director. Features that are not grounds for an exception include above-ground swimming pools and spas, sport courts/equipment, play equipment, greenhouses/sheds from kits, garden beds, animal enclosures, antennae, decks, patios, tents/canopies, landscaping, storage areas, and other temporary and/or portable installations.
b. If it is determined that the only feasible location for an attached or detached ADU is between the primary dwelling’s front or street side façade and a public street, the following standards shall apply:
i. Maximum unit size of 800 square feet of gross floor area; Attachment 4
ii. Minimum front and side setbacks of 4 feet;
iii. Height limit consistent with 6a below;
iv. May not be constructed on any utility or other easement, or within the Traffic Safety Visibility Area per CMC Section 17.30.040E.
6. 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, within one
half-mile mile of SMART
station
Four feet side and
rear
Eighteen feet
Detached, on a property with
existing or proposed
multifamily, multistory
dwelling(s)
Four feet side and
rear
Eighteen feet
Detached Four feet side and
rear
Sixteen or Eighteen feet
No setback shall be required for a 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)(7)(a). b. Any ADU may be allowed up to an additional 2 feet in height to accommodate a roof pitch that is in alignment with that of the primary dwelling. c. No setback shall be required for a 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 Attachment 4
such structures shall be greater of the existing height of the structure or the height set forth for each situation described above, in conformance with 6d below. d. All ADUs shall be limited to a height of two stories, with the exception of an interior ADU in an existing dwelling.
7. Size. ADUs shall be subject to the following requirements related to size:
a. ADUs on lots less than one-half acre in size shall be limited to the following maximum sizes:
Less than two
bedrooms
850 square feet of gross
floor area
Two or more
bedrooms
1,000 square feet of gross
floor area
b. ADUs on lots less than one-half acre in size may exceed the above maximum sizes following submittal of an application and approval of a discretionary design review application.
c. In no case shall any detached ADU exceed one thousand two hundred square feet in size. d. The gross floor area of an attached or interior ADU shall not exceed fifty percent of the existing gross floor area of an existing primary dwelling. (Although an 800 square foot ADU is allowed regardless of the size of the primary dwelling.) e. An ADU proposed through the conversion of an existing accessory structure must be built within the physical dimensions of that structure, with the exception of an expansion of up to one hundred and fifty square feet that is limited to the purpose of accommodating ingress and egress.
f. The minimum allowable 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.
C. Development Standards – JADUs
1. A JADU must be contained entirely within the walls of a proposed or existing single-family dwelling.
2. The size of a JADU shall not exceed 500 square feet of gross floor area. The gross floor area of a shared sanitation facility shall not be included in the maximum gross floor area of the unit.
3. A JADU must include its own entrance separate from that of the primary dwelling.
4. A JADU shall include an efficiency kitchen as defined in California Government Code Section 65852.22.
Attachment 4
5. A JADU may include separate sanitation facilities, or may share sanitation facilities with the primary dwelling, if it has an interior entry to the shared sanitation facilities such that the resident does not need to go outside to access the facilities through an exterior entry.
6. A JADU shall not be offered for sale apart from the principal unit and shall be subject to a deed restriction as required by State ADU law.
7. For the purposes of any fire or life protection ordinance or regulation, a JADU shall not be considered a separate or new dwelling unit.
DD. Parking
1. Unless otherwise specified below, one on-site parking space shall be required for an attached or detached ADU. This parking space is in addition to those spaces required for the primary dwelling(s). On-site parking is not required for an ADU in any of the following instances:
a. The ADU is located within one-half mile walking distance of public transit. b. The ADU is located within an architecturally and historically significant historic district. c. The ADU is part of the proposed or existing primary dwelling or accessory structure. d. When on-street parking permits are required but not offered to the occupant of the ADU. e. When there is a car share vehicle located within one block of the ADU.
2. The required parking space for an ADU may be located in any configuration on the same lot as the accessory dwelling unit, including, but not limited to, as covered spaces, uncovered spaces, tandem parking spaces, or by the use of mechanical automobile parking lifts.
3. Design and development standards for parking for an ADU or JADU shall be consistent with CMC Section 17.36.090.
4. When a garage, carport, covered parking structure, or uncovered parking space is demolished or removed in conjunction with the construction of an ADU or is converted to an ADU, the parking space(s) or structure(s) eliminated are not required to be replaced.
5. There is no minimum parking requirement for a JADU.
Key Definitions
Attached ADU—An ADU that is constructed as a physical expansion (i.e., addition) of and shares a common wall with the primary dwelling unit.
Detached ADU—An ADU that is constructed as a separate structure from the primary dwelling unit.
Interior ADU—An ADU that is created within an existing structure.
JADU—An ADU that is no more than 500 square feet in size and contained fully within the primary dwelling unit.
Commented [NH1]: Delete parking requirements?
Attachment 4
For additional definitions and more details, refer to CMC Chapter 17.90 Definitions and California Government Code Section 66313.
Note: This summary is not intended to replace or supersede any provisions of State ADU Law.
For full details, refer to California Government Code Sections 66310-66342, as may be amended from time to time, CMC Section 17.42.170.
Updated ______