August 13, 2025

California Housing Crisis and the Rise of ADUs

News Summary

California is facing a significant housing crisis, with new housing stock projected to rise by only 0.84% in 2024. Accessory dwelling units (ADUs) are seen as a potential solution, accounting for nearly one-fifth of new units constructed. However, many ADUs are not rented out, limiting their impact on the housing shortage. While the construction of ADUs has increased, challenges such as high costs and occupancy rates remain. A bipartisan bill, the SUPPLY Act, aims to assist homeowners in building ADUs, highlighting the complexity of California’s housing situation and the need for sustainable solutions.

California is grappling with a significant housing crisis, with new housing stock set to increase by only 0.84% in 2024, equating to approximately 125,000 new units. This situation has led to increased attention on accessory dwelling units (ADUs), which have emerged as a potential solution to the housing shortfall.

ADUs are becoming a popular choice among California homeowners, as they accounted for nearly one-fifth of all new housing units constructed in 2024. This trend indicates a growing acceptance of second units, whether attached or detached, on residential properties. Homeowners often view the construction of ADUs as a valuable investment that enhances both property value and available living space.

Despite their proliferation, the effectiveness of ADUs in addressing the housing shortage is debatable. Many ADU owners opt not to rent their units, preferring instead to utilize them for family members or leaving them unoccupied, which complicates efforts to relieve housing pressure. In San Diego County, for instance, 85% of permitted ADUs are occupied by renters, while only 15% are used by owners themselves.

In 2024, the production of ADUs saw a 14.3% increase compared to the previous year, following a 10% increase in 2023. This upward trend reflects a broader embrace of ADUs across the state, with specific regions exhibiting remarkable growth rates. The city of Los Angeles has experienced a 6% overall increase in housing stock from 2020 to 2025, making it a leader in housing growth within Los Angeles County.

Housing growth dynamics vary significantly across California. While Madera County managed a housing stock increase of 2.7% in 2024, smaller cities like Huron reported growth nearing 8%. Los Angeles County stands out for permitting more ADUs per capita than any other county statewide, often favoring lower- and middle-income areas for these developments.

Land use researchers point out that the prevalence of ADUs is connected to communities with lower incomes, higher population density, and a larger proportion of younger and renter-occupied households. Despite recent legislative pushes aimed at increasing ADU construction—including less stringent parking requirements and streamlined approval processes—construction costs remain a significant barrier. Building an ADU can cost hundreds of thousands of dollars, with fees alone reaching upwards of $26,000 based on size and location.

In an effort to address the financial hurdles associated with ADU development, a bipartisan federal bill called the SUPPLY Act has been proposed. This legislation is designed to provide financial assistance to homeowners interested in building ADUs, specifically targeting modest-income families and aiming to foster greater participation in ADU projects.

Ultimately, there remains uncertainty surrounding whether ADUs effectively house individuals who would otherwise experience housing insecurity, or if they primarily serve to create additional space for existing residents. This concern underscores the complexity of California’s housing situation and the challenges that lie ahead in formulating sustainable solutions to the ongoing crisis.

As the state continues to face an uphill battle against inadequate housing supply, the role of ADUs as both a contributor to new home growth and a potential remedy for housing shortages remains a topic of critical importance for policymakers, homeowners, and communities at large.