Chapter 19.41

TWO-UNIT RESIDENTIAL DEVELOPMENT PROJECTS

Sections:

• 19.41.010 Purpose and applicability. 19.41.020 Definitions.

The Sonoma Municipal Code is current through Ordinance 13-2025, passed December 3, 2025.

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• 19.41.030 Planning permit and application requirements. 19.41.040 Review procedures and action. 19.41.050 Maximum number of units. 19.41.060 Building code. 19.41.070 Easements. 19.41.080 Repealed. 19.41.090 Deed restriction. 19.41.100 Fees associated with development. 19.41.110 Time limits and extensions. 19.41.120 Prohibitions. 19.41.130 General requirements. 19.41.140 Restrictions. 19.41.150 Objective development standards. 19.41.160 Denial. 19.41.170 Violations and enforcement.

A. The intent of this chapter is to establish objective standards and regulations to govern the development of qualified Senate Bill 9 development projects on residentially zoned properties within the city of Sonoma. The regulations are established to implement the requirements under California Government Code Section 65852.21. In the event of an inconsistency between this chapter and Government Code Section 65852.21, Government Code Section 65852.21 shall prevail.

B. Two-unit residential developments in single-family zones shall be located, developed, and used in compliance with this chapter. Two-unit residential developments are a permitted residential use only on parcels zoned R-R (Residential – Rural) district, R-L (Residential – Low Density) district, R-S (Residential – Sonoma) district, or R-HS (Residential – Hillside) district.

C. Two-unit residential developments are not subject to the density requirements of the Sonoma General Plan or this code applicable to properties zoned R-R (Residential – Rural) district, R-L (Residential – Low Density) district, R-S (Residential – Sonoma) district, or R-HS (Residential – Hillside) district. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

The definitions below shall apply to the following terms used herein:

The Sonoma Municipal Code is current through Ordinance 13-2025, passed December 3, 2025.

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“Car share vehicle” shall mean a vehicle available for sharing located in a car share vehicle facility approved by the city.

“Car share vehicle facility” shall mean a facility of fixed location approved by the city to permit the storage, pick-up, and drop-off of a car share vehicle.

“Existing structure” or “existing unit” shall mean an existing permitted or otherwise legal single-family dwelling or accessory dwelling unit.

“Ministerial” means no discretionary review or public hearing.

“Sufficient for separate conveyance” shall mean that each attached or adjacent dwelling unit is constructed in a manner adequate to allow for the separate sale of each unit in a common interest development as defined in Civil Code Section 1351 (including a residential condominium, planned development, stock cooperative, or community apartment project), or into any other ownership type in which the dwelling units may be sold individually.

“Two-unit residential development or project” shall mean two primary residential units located on a single lot. The residential units may be located in a single building that contains two residential units (also known as a duplex) or in two detached buildings, including a development which entails adding one new unit to an existing unit, which are developed using the provisions of this chapter and the provisions set forth in California Government Code Sections 65852.21 and/or 66411.7. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

A. Two-Unit Residential Permit Required. A proposal to construct a two-unit residential development shall be subject to first obtaining a two-unit residential permit (sometimes referred to as a “two-unit permit”).

B. Application Submittal Requirements. The submittal requirements for a two-unit residential permit application shall be established by separate policy published by the community development director (“director”). Upon establishment of such submittal requirements, all applicants for a two-unit residential permit must comply with the procedures set forth in the director’s policy.

C. In addition to obtaining a two-unit permit, the applicant shall be required to obtain a building permit, tree removal permit if applicable, and other applicable post-entitlement permits prior to the construction of the dwelling units which are the subject of the two-unit permit. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

A. Completeness Review. The director or designee shall determine whether the application for a two-unit permit is complete pursuant to the requirements of Government Code Section 65943.

The Sonoma Municipal Code is current through Ordinance 13-2025, passed December 3, 2025.

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B. Objective Standard Consistency. The director or designee shall provide an applicant for a two-unit permit with written documentation identifying any inconsistencies with the objective standards applicable to two-unit residential developments within 60 days of determining the application is complete.

C. Ministerial Action. The director or designee shall render a ministerial decision on a two-dwelling-unit permit application upon such application being deemed complete. Notwithstanding anything to the contrary set forth in this code, the director’s or designee’s action to grant or deny an application for a two-unit permit is final and not subject to appeal. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

A. When not located on a site subject to an approved or proposed urban lot split: (1) a maximum of two primary units per parcel meeting the requirements of this chapter are permitted; and (2) either one accessory dwelling unit or junior accessory dwelling unit per primary unit meeting the requirements in Chapter 19.45 SMC is permitted, for a total of up to four units on the subject property.

B. When located on a site subject to an approved or proposed urban lot split, a maximum of two primary units meeting the requirements of this chapter are permitted per parcel resulting from the urban lot split, for a total of two primary units on each of the two resulting parcels. Should a resulting parcel include only one primary development unit, either one accessory dwelling unit or junior accessory dwelling unit meeting the requirements of Chapter 19.45 SMC is permitted. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

All local and state building code provisions applicable to dwelling units shall apply to two-unit residential developments. A two-unit residential development shall meet all building code provisions necessary to accommodate separate conveyance of the subject dwelling units, including but not limited to providing a separate gas, electric, sewer, and water utility connection directly between each dwelling unit and the utility. Prior to issuance of any utility permits, the utility shall verify the service availability for the parcel. The project shall be connected to and served by the utility prior to final inspection approval of the project. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

Dwellings in a two-unit residential development shall not encroach upon any easement. All easements required for the provision of public services and facilities shall be dedicated or conveyed by an instrument in a form acceptable to the director of the community development department. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

The Sonoma Municipal Code is current through Ordinance 13-2025, passed December 3, 2025.

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Prior to the issuance of a building permit for a two-unit residential development dwelling unit, the property owner shall record a covenant with the county recorder’s office, the form and content of which is satisfactory to the city attorney. The covenant shall notify future owners of the approved size and attributes of the units and minimum rental period restrictions. The covenant shall also reflect the number of units approved and provide that no more than two primary residential units and two accessory dwelling units, for a total of four units, may be created on any single parcel or on any two parcels created using urban lot split subdivision procedures. This covenant shall remain in effect so long as a two-unit residential development exists on the parcel. The restrictions shall be binding upon any successor in ownership of the property, may be enforced by the city, and lack of compliance with any provisions of Chapter 19.72 SMC or this chapter may result in legal action against the property owner, including revocation of any entitlement to maintain two dwelling units on the property. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

Two-unit residential developments shall be subject to paying fees associated with development, including development impact fees, Quimby Act fees, connection fees, capacity charges, and other fees or charges as applicable. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

A two-unit permit granted pursuant to this chapter shall be subject to the time limits and extensions of time specified in Chapter 19.56 SMC. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

A two-unit residential development or urban lot split, as specified in state law, shall be prohibited at the following sites, pursuant to state law and as further specified below:

A. Sites located in any of the following, as identified in Government Code Sections 65913.4(a)(6)(B) through 65913.4(a)(6)(K), as of 2021:

The Sonoma Municipal Code is current through Ordinance 13-2025, passed December 3, 2025.

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1. Either prime farmland or farmland of statewide importance, as defined pursuant to United States Department of Agriculture land inventory and monitoring criteria, as modified for California, and designated on the maps prepared by the Farmland Mapping and Monitoring Program of the Department of Conservation, or land zoned or designated for agricultural protection or preservation by a local ballot measure that was approved by the voters of that jurisdiction.

2. Wetlands, as defined in the United States Fish and Wildlife Service Manual, Part 660 FW 2 (June 21, 1993).

3. Within a very high fire hazard severity zone, as determined by the Department of Forestry and Fire Protection pursuant to Government Code Section 51178, or within a high or very high fire hazard severity zone as indicated on maps adopted by the Department of Forestry and Fire Protection pursuant to Section 4202 of the Public Resources Code. This subsection does not apply to sites excluded from the specified hazard zones by a local agency, pursuant to subdivision (b) of Government Code Section 51179, or sites that have adopted fire hazard mitigation measures pursuant to existing building standards or state fire mitigation measures applicable to the development. Two-unit residential developments shall not be permitted within the very high fire hazard severity zones, unless existing building standards within very high fire hazard zones include the high fire construction standards adopted or enforced by the city, as determined by the building official or the fire marshall. No variance or modification to any fire code requirements or high fire construction standards shall be permitted.

4. A hazardous waste site that is listed pursuant to Government Code Section 65962.5 or a hazardous waste site designated by the Department of Toxic Substances Control pursuant to Health and Safety Code Section 25356, unless the State Department of Public Health, State Water Resources Control Board, or Department of Toxic Substances Control has cleared the site for residential use or residential mixed uses.

5. Within a delineated earthquake fault zone as determined by the State Geologist in any official maps published by the State Geologist, unless the development complies with applicable seismic protection building code standards adopted by the California Building Standards Commission under the California Building Standards Law (Part 2.5 (commencing with Section 18901) of Division 13 of the Health and Safety Code), and by any local building department under Chapter 12.2 (commencing with Section 8875) of Division 1 of Title 2 of the Government Code.

opment complies with applicable seismic protection building code standards adopted by the California Building Standards Commission under the California Building Standards Law (Part 2.5 (commencing with Section 18901) of Division 13 of the Health and Safety Code), and by any local building department under Chapter 12.2 (commencing with Section 8875) of Division 1 of Title 2 of the Government Code.

6. Within a special flood hazard area subject to inundation by the one percent annual chance flood (100-year flood) as determined by the Federal Emergency Management Agency in any official maps published by the Federal Emergency Management Agency. If a development proponent is able to satisfy all applicable federal qualifying criteria in order to provide that the site satisfies this subsection and is otherwise eligible for streamlined approval under this section, a local government shall not deny the application on the basis that the development proponent did not comply with any additional permit requirement, standard, or action adopted by that local government that is applicable to that site. A development may be located on a site described in this subsection if either of the following are met: (a) The site has been subject to a letter of map revision prepared by the Federal Emergency Management Agency and issued to the local jurisdiction; or (b) the site meets Federal Emergency Management Agency requirements necessary to meet minimum flood plain management criteria of the National Flood Insurance Program pursuant to Part 59 (commencing with

The Sonoma Municipal Code is current through Ordinance 13-2025, passed December 3, 2025.

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Section 59.1) and Part 60 (commencing with Section 60.1) of Subchapter B of Chapter I of Title 44 of the Code of Federal Regulations.

7. Within a regulatory floodway as determined by the Federal Emergency Management Agency in any official maps published by the Federal Emergency Management Agency unless the development has received a no rise certification in accordance with Section 60.3(d)(3) of Title 44 of the Code of Federal Regulations. If a development proponent is able to satisfy all applicable federal qualifying criteria in order to provide that the site satisfies this subsection and is otherwise eligible for streamlined approval under this section, a local government shall not deny the application on the basis that the development proponent did not comply with any additional permit requirement, standard, or action adopted by that local government that is applicable to that site.

8. Lands identified for conservation in an adopted natural community conservation plan pursuant to the Natural Community Conservation Planning Act (Chapter 10 (commencing with Section 2800) of Division 3 of the Fish and Game Code), habitat conservation plan pursuant to the Federal Endangered Species Act of 1973 (16 U.S.C. Sec. 1531, et seq.), or other adopted natural resource protection plan.

9. Habitat for protected species identified as candidate, sensitive, or species of special status by state or federal agencies, fully protected species, or species protected by the Federal Endangered Species Act of 1973 (16 U.S.C. Section 1531, et seq.), the California Endangered Species Act (Chapter 1.5 (commencing with Section 2050) of Division 3 of the Fish and Game Code), or the Native Plant Protection Act (Chapter 10 (commencing with Section 1900) of Division 2 of the Fish and Game Code).

10. Lands under conservation easement.

B. Historic Resources. Sites located in an historic district, property or structure designated pursuant to a local ordinance or included on the State Historic Resources Inventory or city of Sonoma’s local inventory of historic resources. Without limiting the generality of the foregoing, two-unit residential developments are not permitted in the following city historic districts or areas: Broadway corridor district; plaza district; historic train district; Sebastiani cottage district; on parcels identified on the city’s local historic resources list; and other historic districts.

• C. Rental Units. Sites that would require demolition or alteration of any of the following types of housing:

  1. Housing that is subject to a recorded covenant, ordinance, or law that restricts rents to moderate, low, or very low incomes;

  2. A rent-controlled unit;

  3. A unit that has been occupied by a tenant within the past three years; or

4. A parcel or parcels on which an owner of residential real property has exercised the owner’s rights under Chapter 12.75 (commencing with Section 7060) of Division 7 of Title 1 of the Government Code to withdraw accommodations from rent or lease within 15 years before the date of the application submittal.

5. Nonconforming Development. Sites already developed with two or more existing residential units, nonresidential uses, or mixed-use, shall not use the provisions of this section to add floor area, add

The Sonoma Municipal Code is current through Ordinance 13-2025, passed December 3, 2025.

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residential units, or make any other alterations to the buildings or site otherwise prohibited by this chapter, unless the development complies with all the standards of this chapter.

6. Adverse Impacts. Sites the director finds that the proposed development would have a specific, adverse impact on public health and safety or the physical environment that cannot be feasibly mitigated or avoided. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

A proposed two-unit residential project shall comply with the following requirements:

• A. The applicable flood damage prevention regulations contained in Chapter 14.25 SMC.

B. Development adjacent to a creek shall comply with SMC 19.40.020 (Creekside development). Construction of a two-unit project shall maintain a minimum 30-foot setback from the top of a creek bank (Nathanson Creek or Fryer Creek), except along Sonoma Creek, where a 50-foot setback shall be required. Additional setback dimensions or areas may be necessary to protect sensitive environmental resources (e.g., vernal pools). Setbacks adjacent to creekside paths or open spaces shall be measured from the outside boundary of the path or open space. The applicant shall provide the building department with all applicable permits from outside agencies, which may include, but not be limited to, the San Francisco Bay Regional Water Quality Control Board, California Department of Fish and Wildlife, the Army Corps of Engineers, State Water Resources Control Board and/or U.S. Fish and Wildlife Service when requested by the building official.

• C. A permanent address that complies with fire district standards is required for each dwelling unit.

• D. The project shall comply with the applicable regulations contained in the California Building Standards Code as amended and adopted by the city of Sonoma.

E. Prior to issuance of a building permit for the construction of a two-unit residential project, the municipal water utility shall verify water service availability for the parcel. The project shall be connected to and served by the municipal water utility system prior to final inspection approval of the project.

F. Prior to issuance of a building permit for the construction of a two-unit residential project, the public sewer system utility shall verify public sewer service availability for the parcel. The project shall be connected to and served by the public sewer system prior to final inspection approval of the project.

G. Replacement Housing. If any existing dwelling unit is proposed to be demolished, the applicant will comply with the replacement housing provisions of Government Code Section 66300(d).

H. Development standards set forth in a planned unit development or specific plan shall apply to any housing development except that any such planned unit development or specific plan standard cannot be applied if it would either: (1) result in a conflict with standards set forth by state law for a housing development; or (2) preclude a housing development that meets the applicable requirements of state law or this chapter.

The Sonoma Municipal Code is current through Ordinance 13-2025, passed December 3, 2025.

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I. The correction of nonconforming zoning conditions may not be required as a condition of approval. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

A two-unit residential development shall be subject to the following restrictions:

A. The development and use of dwelling units in two-unit residential projects shall only be valid if in conformance with this chapter and permitted under this chapter.

B. Any owner wishing to modify the number of units in an approved two-unit residential development must request termination of the use of one or more of the dwelling units using the procedures set forth in this chapter and satisfy all zoning and development standards such as setbacks, floor area and lot coverage. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

A. General Requirements. Two-unit residential developments are subject to the development standards in this section as adopted and amended from time to time. In addition, two-unit residential projects shall conform to all objective zoning, subdivision, and design standards applicable to the respective residential zoning district in which the project is located, except as expressly provided in this chapter. Notwithstanding the above, if the application of an objective standard would have the effect of physically precluding the construction of up to two units (each possessing no greater than 800 square feet of floor area) on a single parcel, compliance with that objective standard shall be waived but only to allow up to two units 800 square feet each.

1. Allowed Uses. The only uses allowed on parcels on which two-unit residential development is permitted and, in the units, created under a two-unit residential development shall be residential uses and may not be used for rentals of less than 30 days, and rental terms shall not allow termination of the tenancy prior to the expiration of at least one 31-day period occupancy by the same tenant.

2. Minimum Lot Size. The minimum size of any parcel on which a two-unit residential development is permitted is 1,200 square feet.

3. Maximum Floor Area. Maximum floor area ratio for a two-unit residential development shall be that specified for the zoning district in which the two-unit residential development is located.

4. Height. Maximum height for a two-unit residential development shall be that specified for the zoning district, however any portion of a new dwelling unit constructed within a reduced setback from the underlying zone shall be permitted to build to a maximum 16 feet in height. In no case shall the building exceed the height of the underlying zone to allow the development of two 800-square-foot units, when it is feasible to modify other development standards to allow the development.

The Sonoma Municipal Code is current through Ordinance 13-2025, passed December 3, 2025.

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5. Site Coverage. Maximum site coverage for a two-unit residential development shall be that specified for the zoning district in which the two-unit residential project is located. “Site coverage” means the percentage of total site area occupied by structures (including but not limited to the residential units, garage, all accessory buildings, and decks over 18 inches above grade), and areas necessary for the ingress, egress, outdoor parking, and circulation of motor vehicles.

6. Setbacks. Setbacks for a two-unit residential development shall be that specified for the zoning district, however setbacks from the side and rear lot property lines shall be no less than four feet, except in the case of existing structures or structures constructed in the same location and to the same dimensions as an existing structure.

7. Building Form.

• a. Dwelling units in a two-unit residential development shall include permanent provisions for living, eating, and sleeping, including a kitchen and bedroom closet or other storage.

  • b. Dwelling units in a two-unit residential development shall have separate exterior entries.

c. A permanent foundation for each dwelling unit in a two-unit residential development and attached accessory uses shall be required.

8. Off-Street Parking.

a. One covered or uncovered off-street parking space is required per dwelling unit in a two-unit residential project, except as exempted below.

i. No parking is required if the parcel is located within one-half mile walking distance of either a high-quality transit corridor, as defined in subdivision (b) of Section 21155 of the Public Resources Code, or a major transit stop, as defined in Section 21064.3 of the Public Resources Code; or if there is a designated parking space for a car share vehicle located within one block of the parcel.

b. The location of the required parking space(s) shall not obstruct the required parking of each dwelling unit.

c. Tandem parking is prohibited. Each unit must have its own parking space which can be accessed without crossing over or encroaching upon the other unit’s parking space.

d. When an existing garage, carport, or other covered parking structure is converted or demolished in order to construct a new unit, at least one replacement parking space, which may be covered or uncovered, must be provided for each unit, unless the project is exempt from parking requirements.

9. Access to a Public Street. Every dwelling unit shall have permanent means of access to a public street. When automobile parking is required or proposed, vehicular access to a public street or alley shall be provided by a driveway that complies with the minimum width, slope, materials, and other standards consistent with the California Fire Code and Chapter 12.12 SMC.

The Sonoma Municipal Code is current through Ordinance 13-2025, passed December 3, 2025.

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10. Storm Water Management. Two-residential unit development must comply with the city’s storm water runoff requirements pursuant to Chapter 13.32 SMC (Stormwater Management and Discharge Control).

11. Landscaping. A complete application for a two-unit residential permit shall include a landscape plan which must comply with the city’s water efficient landscaping ordinance (Chapter 14.32 SMC) and SMC 19.40.060 (Landscape standards), 19.40.070 (Open space for multifamily residential projects), 19.40.100 (Screening and buffering), and Chapter 19.46 SMC (Fences, Hedges and Walls).

12. Outdoor/Common Space. Outdoor/common space for a two-unit residential development shall be that specified for the zoning district.

13. Utilities. Private underground utility services, including municipally supplied water, sewer, gas, electricity, cable TV and telephone, shall be available for extension to and connection with all units in a two-unit residential development. All dwelling units in a two-unit residential development must be able to connect and shall connect to municipally supplied water, sewer, gas, and electricity services. All existing and proposed utility distribution facilities (including electric, telecommunications and cable television lines) installed in and for the purpose of supplying service to any dwelling unit(s) proposed as part of a two-unit residential project shall be installed underground. Equipment appurtenant to underground facilities, including surface-mounted transformers, pedestal-mounted terminal boxes and meter cabinets, and concealed ducts, shall also be underground. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021).

• A. Denial of a Two-Unit Residential Development. The director, or designee, shall not approve a two-unit residential development under any of the following circumstances:

  1. The project proposes creation of more than two units total as described in this chapter.

  2. The urban lot split does not meet the requirements of SMC Title 19, Integrated Development Regulations and Guidelines.

3. Based on a preponderance of the evidence, the building official finds that the proposed housing development project would have a specific, adverse impact, as defined and determined in paragraph (2) of subdivision (d) of Government Code Section 65589.5, upon public health and safety and for which there is no feasible method to satisfactorily mitigate or avoid the specific, adverse impact. (Ord. 01-2025 § 2 (Exh. A), 2025).

It is unlawful for any person to violate any provision of this chapter. Violations are subject to the enforcement penalties and procedures of Chapters 1.30 and 19.90 SMC, administrative penalties and development code

The Sonoma Municipal Code is current through Ordinance 13-2025, passed December 3, 2025.

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enforcement. The remedies provided therein are cumulative. (Ord. 01-2025 § 2 (Exh. A), 2025; Ord. 13-2021 § 2, 2021. Formerly 19.41.160).