SB 9  (2021 Chapter 162) Housing development approvals: Duplex and lot split zoning.

The California Legislature has continued to address California’s housing shortage by expanding opportunities for construction of duplexes and fourplexes in residential areas.  Upon passage of SB 9, there are estimates of over 700,000 market-feasible homes to be built statewide.  However, as with other housing legislation there is no silver bullet to addressing the housing shortage statewide, so each bill must be viewed as one more tool for homeowners, builders, and cities to address the shortage.  SB 9 was passed in 2021, and become effective on January 1, 2022, but some critics have already deemed the legislation a failure because only two percent of homeowners are filing applications for housing development approvals under the law and cities are opposing the implementation of the legislation due to loss of local land use controls  in  their cities.

Promotes Small-Scale Neighborhood Development

Government Code §§ 65852.21 and  66411.7 promotes small-scale neighborhood residential development by streamlining the process for a homeowner to create a duplex or subdivide an existing lot.  Any new housing created as a result of this SB 9 legislation must meet a specific list of qualifications that ensure the protection of historic districts, environmental quality, and existing tenants vulnerable to displacement.   The bill establishes a statewide path for homeowners seeking to create a duplex or subdivide an existing residential parcel by ensuring local governments approve qualified applications without discretionary review, eliminating overly burdensome requirements that slows qualified application. 

Housing Development Must Satisfy Several Location Qualifying Criteria:

  • The project is in a city or urbanized portion of an unincorporated area within a county.
  • The project site is not located on or in any of the following:
    • Prime farmland, or farmland of statewide importance
    • Wetlands
    • Within a very high fire severity zone
    • A hazardous waste or hazardous list sit
    • Within a delineated earthquake fault zone,
    • Within a 100-year flood zone,
    • Within a floodway
    • Identified for conservation n an adopted natural community conservation plan,
    • Habitat for protected species or
    • Land under conservation easement 

Restrictions on Impacts on Affordable and Historic Buildings:

  • The project cannot require demolition or alteration of any housing if 1) housing is restricted affordable housing, 2) subject to rent control, or 3) contains tenant occupied housing in the last three years. 
  • The project site cannot be withdrawn from the rental market (i.e., under the Ellis Act) within the past 15 years.
  • The project does not propose demolition of more than 25 percent of the easing exterior walls unless wither 1) the local ordinance allows more demolitions, or 2) the site has not been occupied by a tenant in the past three years.
  • The project site is not within a historic district or property included on the California Historical Resources Inventory or within a site that is designated or listed as a city or county landmark  or historic property or district pursuant to a city or county ordinance. 

Local Agencies (Cities and Counties) Authority and Zoning Limitations:

To be considered for ministerial approval, the proposed development project must meet certain local development criteria:

  • A local agency may impose objective zoning, subdivision and design review standards  providing such objective standards do not preclude the construction of either of the two units being less than 800 square feet in area.
  • No setbacks are required for an existing structure, or a structure constructed in the same location and to the same dimensions as an existing structure.    In other circumstances, the  local agency may require four-foot side and real yard setbacks. 
  • Parking of no more than one space per dwelling unit is allowed, except no parking required for projects a) within a half-mile walking distance of a high-quality transit corridor or a major transit stop or b) within one block of car share. 
  • A local agency may deny such a housing development project if there is a written finding that the project would create a specific adverse impact upon public health and safety or the physical environment that there is no way to mitigate. 
  • The rental of any unit created must be for a term longer than 30 days.
  • The California Coastal Act still applies, except that no public hearing is required for Coastal Development Permits for housing developments pursuant to this legislation. 
  • A local agency may not be required to permit an accessory dwelling unit (ADU) or Junior ADU (JADA) in addition to the second unit it there is a lot split. 
  • A local agency may not reject housing solely on the basis that a project proposes adjacent or connected structures provided that the structures meet building code safety standards and are sufficient to allow separate conveyance. 

If these criteria are satisfied, the local agency must approve the project ministerially (i.e., without discretionary review or hearings).  Projects approved  ministerially are not subject to the California Environmental Quality Act (CEQA).   

Lot Splits To Be Approved Ministerially Pursuant to a Parcel Map

In addition, SB 9  (Government Code § 66411.7) requires qualifying lot splits to be approved ministerially pursuant to a parcel map, upon meeting a number of criteria, including many of the same  criteria as specified above  pursuant to Government Code § 65852.21).  Additional criteria including the following:  

  • Each parcel must be at least 40 percent of the original parcel’s size
  • Each  parcel must be at least 1,200 square feet in lot size unless the local agency permits smaller lot size per ordinance.
  • There cannot be a sequential lot split on the same parcel, nor can there be a lot split if the owner of the parcel being subdivided  (or someone working  in concert with that owner0 has subdivided an adjacent parcel pursuant to this lot split legislation. 
  • No right-of-way dedication or off-site improvement may be required. 
  • The parcel must be limited to residential use.
  • An affidavit that the applicant intends to use one of the housing units as a principal residence for at least three years from the date of approval is required.
  • The local agency shall not require a condition that requires correction of nonconforming zoning conditions.
  • For each parcel created, a local agency is not required to permit more than two dwelling units on a parcel.

A local agency may require as, conditions of approval: 

  • Easements for public services and facilities.
  • Access to the public right-of-way

Cities’ Ability to Craft Objective Standards Consistent with the Housing Crisis Act of 2019 (SB 330)

Government Code 65852.21(b) explicitly authorizes local agencies to “impose objective zoning standards, objective subdivision standards, and objective design review standards” provided the standards to not physically preclude the construction of up to two 800 square feet units, subject to certain other restrictions.[1]  However, this provision does not directly address the application of the Housing Crisis Act of  2019 (Government Code § 66300(b)(1)(A)).   Government Code 66300 limits an affected county or city[2] in its ability to amend its general plan, specific plans, or zoning code in a way that would improperly reduce the intensity of residential developments.    “Reducing the intensity of land use includes,” but is not limited to, reductions to height, density, or floor area ratio, new or increased open space or lot size requirements, new or increased setback requirements, minimum frontage requirements, or maximum lot coverage implications, or any other actin that would individually or cumulatively  reduce ethe site’s residential development capacity.  (Govern Code § 66300(b)(1)(A).   Affected cities and counties are prohibited from reducing the intensity of land use “below what was allowed under the land use designation or zoning ordinances of the affected county or affected city, as applicable, as in effect on January 1, 2018.”  (Government Code § 66300)  Since the typical jurisdiction’s zoning ordinance on that date would not have allowed the projects authorized by SB 9, subjecting SB 9 projects to standards different from what apply to traditional single-family homes is not necessarily reducing the intensity of land use below that allowed on January 1, 2018. 

A reduction in the intensity of land use is defined as an action that would reduce a site’s “residential development capacity.”  That phase is not defined and is not used anywhere else in the Planning and Zoning Law.  However, the most logical way to understand SB 330’s requirements is to prohibit a change in zoning standards would reduce the number of housing units that can be constructed and not the size of these units.  This is consistent with the findings the Legislature made when adopting SB 330 that the development of more housing units was necessary to address the housing crisis.  In the  context of multi-family housing, changes in zoning standards, such as a reduction in height, can directly impact the number of housing units that can be built on a site.  The same is true for SB 9, where state law already restricts the number of units that can be constructed.  For example, a strict regulation limiting SB 9 units to 800 square feet regardless of other standards would obviously limit the size of units built pursuant to SB 9, but would not limit the number of units.  Accordingly, many types of regulations will arguably not reduce the “residential development capacity” of sites in single family zoning districts.  SB 330 does not restrict a city’s ability to adopt a regulation specific to SB 9 projects if the regulation does not reduce “residential development capacity.”  Thus, the presence or absence of similar objective standards in a city’s zoning code to other types of residential projects arguably does not impact whether the city may adopt additional objective standards that are only applicable to SB 9 projects if such standards are consistent with state law.

Examples of Discretion a City or County Does Have on SB 9 Projects

As previously stated SB 9 allows cities and counties to impose objective zoning, subdivision and design review standards that do not conflict with SB 9.  Local agencies may also elect to impose less stringent requirements than those contained in state law.  If local agencies regulations do not violate SB 9 (such as the requirement to allow at least an 800 square foot unit), local agencies have discretion to:

Development Standards

  • Front Yard SetbacksCities may retain the standard front yard setback requirements or be more permissive and reduce the mandatory setbacks.
  • Side and Rear Setbacks.  Local agencies may be more permissive than the 4 four-foot state law maximums. 
  • Heights. SB 9 does not directly regulate minimum or maximum heights or limits on stories.  However, for multi-family units, be aware of the restrictions of SB 330.
  • Maximum Size.  Must allow units to be at least 800 square feet.  Local Agencies may increase the maximum size.  
  • Parking.  At most one parking space per unit is allowed – local agencies can opt to require less parking.
  • Design Requirements.  May authorize objective design review standards under SB 9 that do not physically preclude construction of an 800 square foot unit.  Local agencies have implemented a number of requirements that would qualify as objective design standards:
    • Eave protection
    • Roof pitch
    • Façade materials and minimum articulation
    • Color requirements (e.g., matching the color of the primary dwelling)
    • Design requirements for features such as windows, porches, balconies, etc.
    • Exterior lighting direction and shield
    • Height requirements for units, entrances, fences, retaining walls, and landscape.
  • Incentives.  Local agencies may include incentives to comply with specific standards.  For example, in exchange for applicants volunteering to comply with setback requirements that are more stringent than otherwise allowed by SB 9, a local agency could allow additional height or stories for such units. 

Lot Splits

Requires for qualifying parcels, ministerial approval of two-unit housing developments in single-family zoning districts and would allow single-family parcels to be subdivided into two lots.

Accessory Dwelling Units

SB 9 and Accessory Dwelling Unit (“ADU”) Law (Government Code §§ 65852.2 and 65858.22) are complementary.  The requirements of each can be implemented in ways that result in development with both “SB 9 Units” and ADUs.  However, specific provisions of SB 9 typically overlap with State ADU Law only to a limited extent on a relatively small number of topics.

Units Defined.  The three types of housing units that are described in SB 9 and related ADU Law are presented below to clarify which development scenarios are (and are not) made possible by SB 9. 

            Primary Unit.  A primary unit (also called a residential dwelling unit or residential unit) is typically a single-family residence or a residential unit within a multi-family residential development.   Examples of primary units include a single-family residence, a duplex, a four-plex. 

            Accessory Dwelling Unit.  An ADU is an attached or detached residential dwelling unit that provides complete independent  living facilities for one or more person and is located on a lot with a proposed or existing  primary residence.  It includes permanent provisions for living, sleeping, eating, cooking, and sanitation on the same parcel on which the single-family or multifamily dwellings or will be situated. 

            Junior Accessory Dwelling Unit.  A Junior ADU is a unit that is no more than 500 square feet in size and contained entirely within a single-family residence.  A Junior ADU may include separate sanitation facilities or may share sanitation facilities with the existing structure. 

Number of ADUs Allowed.  ADUs can be combined with primary units in a variety of ways to achieve the maximum unit counts provided for under SB 9. SB 9 allows for up to four units to be built in the same lot area typically used for a single-family home.  The calculation varies slightly depending on whether a lot split is involved, but the outcomes regarding total maximum unit counts are identical. 

            Lot Split.  When a lot split occurs, the local agency must allow up to two units on each lot resulting from the lot split.  In this situation all unit types (i.e. primary unit, ADU, and Junior ADU) count toward this two-unit limit.  For example, the limit could be reached on each lot by creating two primary units, or a primary unit and an ADU, or a primary unit and a Junior ADU.  By building two units on each lot, the overall maximum of four units allowed under SB 9 is achieved.  (Government Code § 66411.7(j)).   Note that the local agency may choose to allow more than two units per lot if desired. 

            No Lot Split.  When a lot split has not occurred, the lot is eligible to receive ADUs and/or Junior ADUs as it ordinarily would under ADU law.  Unlike when a project is proposed following a lot split, the local agency must allow, in addition to one or two primary units under SB 9, ADUs and /or JADUs under ADJU Law. 


One year in, there is limited utilization of the benefits of SB 9.  Many California cities, including St. Helena and Yountville, have passed urgency ordinances implementing additional requirements required prior to implementing the benefits of SB 9.  The Turner Center for Housing and Innovation (https://ternercenter.berkeley.edu/reasearch-andpolcy/sb-9-turns-one-applications/ )  showed for 2022, a sample of 13 municipalities  that shared data on application, Los Angeles approved 38 SB 9 units and zero lot splits.[3]  Eight municipalities, including Anaheim, Bakersfield, Berkeley, Danville, Long Beach, San Diego, San Jose and Santa Maria, did not approve a single SB 9 unit in 2022.[4]   The survey concluded that one reason cited by planners is that statewide ADU laws guarantee lower fees, no owner-occupancy requirements, standardized designed rules, and permitting streamlining and offer a better deal for building looking to build additional housing on single-family lots.  SB 9 projects enjoy none of these protections.  Without these protections for SB 9 projects, SB 9 is unlikely  to meet its full potential.  By comparison, Los Angeles permitted 5,064 ADUs in 2021, and while the data for 2022 is not yet available, it is likely to be similar. 

[1]  To be considered “objective”, such standards must involve “no personal or subjective judgement by a public official” and are uniformly verifiable by an external and unform benchmark that is available and knowable by both the developer and the public official prior to submitting an application.  (Government Code §§ 65852.21(i)(2); 66411.7(m)(1).

[2]   Affected cities is any city, including a charter city, that is in an urbanized areas or urban cluster, as designed by the US Census Bureau.  Any city of a population of less than 5,000 and not located within an urbanized area is exempt.  Based on HCD’s determination, 445 of the 482 cities statewide qualify as “affected cities.”  Counties have a similar definition with 22 of the 58 counties being qualified as “affected counties.” 

[3] By comparison, Los Angeles permitted 5,064 ADUs in 2021, and while the data for 2022 is not yet available, it is likely to be similar. 

[4]   Danville and Saratoga received amount the most split applications in absolute terms – 20 and 21 respectively.  Danville approved 13 of these applications, while Saratoga approved two.  This may be due the large lots sizes in these cities. 

William W. Abbott is Of Counsel and Patrick L. Enright is an Attorney at Abbott & Kindermann, Inc.  For questions relating to this article or any other California land use, real estate, environmental and/or planning issues contact Abbott & Kindermann, Inc. at (916) 456-9595.

The information presented in this article should not be construed to be formal legal advice by Abbott & Kindermann, Inc., or the formation of a lawyer/client relationship. Because of the changing nature of this area of the law and the importance of individual facts, readers are encouraged to seek independent counsel for advice regarding their individual legal issues.