Upzoning refers to zoning code changes that increase the amount of development allowed. Upzoning is applied more broadly (e.g., over an entire zoning district) whereas rezoning is typically applied to specific properties (e.g., rezoning of one or more parcels from one district to another district). Upzoning can increase housing affordability by providing more housing in existing residential areas. It can also help achieve many economic, social, and environmental goals including Affirmatively Furthering Fair Housing, implementing sustainable communities’ strategies, and creating areas with mixed incomes and access to high-resource areas. 

Upzoning can also be used to implement general and/or programmatic goals to accommodate a jurisdiction’s regional housing needs allocation. If a jurisdiction does not have a sufficient housing site inventory, they are typically required to have programs within their housing element to identify and zone land within a specified time frame. Not having adequate sites can also result in a “conditional” certification of a housing element and ongoing reporting and follow-up with HCD. A jurisdiction may need to engage in broad upzoning of large areas of a city (e.g., rezone enough underused or vacant residential parcels to a minimum of 20-30 units per acre to accommodate lower-income housing allocations) and/or more targeted area-specific upzoning (e.g., along transit corridors). These options are discussed further below. 

Broad upzoning. Accessory Dwelling Unit and Junior Accessory Dwelling Unit laws along with recently passed legislation (SB 9) that allows urban lot splits and two-unit developments on existing single-family lots are broad forms of upzoning. Additionally, SB 10 provides a new upzoning tool that allows jurisdictions to zone parcels for up to 10 units in areas that are “transit-rich” or considered “urban infill” as defined by State law. All these laws create additional capacity to accommodate regional housing need allocations, but they may not be sufficient to address long-term affordability requirements, as they do not necessarily result in income/deed-restricted forms of affordable housing that can be counted towards lower-income production goals.

Area or site-specific upzoning. An alternative to broad upzoning is to upzone specific sites or areas of a city, such as a downtown or transit corridor. Examples include:

Mixed-use zoning is a way to upzone property to incorporate housing within existing commercial zones. Jurisdictions can still preserve commercial land use goals, especially in neighborhood, office, and retail commercial type zoning districts by requiring housing to be located above and/or behind commercial uses. If this approach is employed, a jurisdiction should specify the minimum amount of commercial development that is required along with spatial requirements to avoid token or unusable commercial development. 

Mixed-use zoning can be applied as a requirement or as an optional zoning overlay, keeping in mind that the “optional approach” could preclude such sites from being counted to meet regional housing needs in the housing element.

Area, community, or specific plans can be used to upzone newly developing areas or to revitalize and integrate new development within an existing area. The primary advantage of such plans is that all the basic planning requirements (e.g., land use, zoning, and backbone infrastructure needs) are established and environmental review is completed. This, in turn, can provide for a streamlined review of subsequent projects. 

Upzoning of transit-oriented development TOD areas around transit stations or along high frequency bus corridors (usually with headways of fifteen minutes or less during peak commute times) has the dual benefit of providing more housing accessible to transit and creating a ridership base that enhances the economic and financial viability of the mass transit investment. The TOD section of this report explores this opportunity in greater detail.

Challenges. Having an adequate inventory of sites zoned at the minimum densities required to meet obligations for lower-income households is a key component for housing elements. Most jurisdictions in the San Joaquin Valley will need to zone for at least 20 units per acre (30 units per acre in cities with populations over 100,000) to meet lower-income housing allocation requirements, and upzoning will be a critical method to achieve this.

Relevant State Law

Senate Bill No. 9 (SB 9) (2021). Housing Development: Approvals. Urban Lot Splits and Two-Unit Developments. 

Senate Bill No. 10 (SB 10) (2021) Housing Development: Density. A Tool for Residential Upzoning in transit-rich areas.

Senate Bill No. 478 (SB 478) (2021). Floor Area Ratio Allowances for Certain Housing Projects. 

Government Code Section 65589.5. Density Bonuses and Other Incentives.

Government Code Section 66300 (b)(1)(A). Prohibits downzoning.


HCD. Map of Designated Jurisdictions Prohibited from Certain Zoning-Related Actions. 

Sightline Institute. Video: Invisible Walls Shutting You Out? 

Curbed. Will upzoning neighborhoods make homes more affordable? 

Planetizen. What is Missing Middle Housing?


Governing.com. A Recipe for Achieving Real Housing Affordability.

Terner Center for Housing Innovation. Will Allowing Duplexes and Lot Splits on Parcels Zoned for Single-Family Create New Homes?

American Planning Association, Northern California Chapter. Why zoning for Middle Housing doesn’t make it so. Upzoning approaches in different areas of a city. 



City of Ashland. Questions and Answers for the proposed Minimum Density Ordinance amendments to R-2 and R-3 zones.

Puget Sound Regional Council. Minimum Densities.