What's the difference between an ADU and an SB-9 project?
While both ADUs and SB-9 projects contribute to increasing housing density in California, they differ in scope, regulatory framework, and impact on neighborhood character. ADUs offer a more incremental approach to adding housing to existing properties, while SB-9 projects involve a more transformative approach through lot splitting and creating multiple new dwelling units.
While both Accessory Dwelling Units (ADUs) and Senate Bill 9 (SB-9) projects aim to increase housing density and affordability in California, they represent distinct approaches with different implications for homeowners and communities. Understanding their differences is crucial for navigating the evolving landscape of residential development.
TIP: Use our ADU Equity Growth Calculator to help estimate your property's value increase with an ADU.Fundamental Concepts and Purpose
ADU
An ADU is a secondary, self-contained dwelling unit located on the same lot as a primary single-family residence.
- Its purpose is to provide additional housing options within existing residential areas, often for rental income, multigenerational living, or flexible living arrangements.
- ADUs focus on maximizing the use of existing residential lots without fundamentally altering their subdivision.
SB-9
SB-9 is a California state law that allows homeowners to split their single-family lots and build up to two primary dwelling units on each resulting lot, in addition to ADUs.
- Its primary goal is to significantly increase housing density and address the state's housing crisis by facilitating the creation of multiple new housing units.
- SB-9 projects involve lot splitting, which fundamentally alters the existing lot configuration.
Scope and Scale of Development
ADU
ADUs are typically smaller-scale projects, focusing on adding a single secondary dwelling unit to an existing property.
- They can be attached or detached from the primary residence and are subject to local size and design regulations.
- ADUs increase density by adding a single unit.
SB-9
SB-9 projects involve a larger-scale development, potentially creating up to four new housing units (two on each resulting lot) from a single-family lot.
- This represents a significant increase in density and can dramatically alter the character of single-family neighborhoods.
- SB-9 projects can involve lot splits.
Regulatory Framework
ADU
ADUs are primarily regulated by local zoning and building codes, which can vary significantly between cities and counties.
- While California has enacted state-level legislation to streamline ADU development, local jurisdictions still retain some control over size, setbacks, and other regulations.
- California has made strides to reduce the local government's ability to prevent ADU construction.
SB-9
SB-9 is a state law that preempts specific local zoning regulations, allowing for lot splitting and increased density under particular conditions.
- It provides a statewide framework for development, but local jurisdictions may still impose certain objective standards.
- SB-9 is designed to remove local control over the amount of housing being built.
Impact on Neighborhood Character
ADU
ADUs generally have a less significant impact on neighborhood character, as they typically involve adding a single secondary dwelling unit to an existing property. Careful design and planning can help integrate ADUs seamlessly into existing neighborhoods.
SB-9
SB-9 projects can significantly alter neighborhood character due to lot splitting and the potential for multiple new dwelling units. Concerns about increased density, traffic congestion, and changes to neighborhood aesthetics are common.
Intended Use and Target Demographic
ADU
ADUs can serve various purposes, including rental housing, multigenerational living, and flexible living arrangements. They can cater to a diverse range of residents, including individuals, couples, and small families.
SB-9
SB-9 projects primarily aim to increase the overall housing supply, focusing on creating market-rate and potentially affordable housing units. They may attract more residents, including families and individuals seeking homeownership.
Key Considerations
ADU
Homeowners must navigate local zoning regulations, obtain necessary permits, and ensure compliance with building codes. Financial planning is crucial, as ADU construction can be a significant investment.
SB-9
Homeowners must understand the specific requirements of SB-9, including lot size restrictions, setback regulations, and allowable dwelling unit configurations. Navigating the lot-splitting process and obtaining necessary approvals can be complex.
