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Density Bonus Program

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Sonoma County’s density bonus program is a crucial tool to incentivize more affordable housing production. The County’s program far exceeds State density bonus requirements, allowing a by-right 100 percent increase in density for rental housing developments that provide 40 percent of the total units as affordable to households with incomes at 50–60 percent of the area median income. The rental density bonus program is the most popular affordable housing incentive program in the County and is used by both nonprofit and for-profit developers.

The County’s density bonus program received the 2017 California State Association of Counties (CSAC) Challenge Award for innovative programs in county government. 


A density bonus offers a regulatory incentive for developers to build more affordable housing by increasing the allowable residential density and providing incentives to reduce housing costs.  When a developer agrees to build affordable housing units in addition to those required as part of the affordable housing program, the density bonus allows the construction of a greater number of market-rate units than would be allowed otherwise under the General Plan and zoning ordinance for a specific parcel.


The County’s Housing Opportunity Area density bonus programs apply only to projects in the Urban Service Areas that provide affordable units. The Rental Housing Opportunity Program (formerly Type A) applies only to multi-family units in the R2 (Medium Density Residential) and R3 (High Density Residential) zoning districts and the Ownership Housing Opportunity Area Program (formerly Type C) applies to single-family residential projects in the R1 (Low Density Residential), R2, and PC (Planned Community) zoning districts. 

Permit Requirements

A request for a density bonus is required at the time an application for a development permit is submitted. A Housing Proposal that details the type, location, size, bedroom count, and affordability levels for each unit is required. The application must specify any incentives that the developer is requesting in addition to the increase in density. Prior to issuance of the project’s building permits, an Affordable Housing Agreement between the applicant and the Sonoma County Community Development Commission must be executed and recorded.

Summary of Provisions

Rental Housing Opportunity projects may qualify for a 100 percent increase in the allowable density up to a maximum of 40 units per acre if at least 40 percent of the units are restricted to lower-income rentals.

Ownership Housing Opportunity projects may qualify for a density bonus up to a maximum of 11 units per acre if 20 percent of the units are restricted to low-income households and the remaining units are restricted to moderate-income households.