Where Will Accessory Dwelling Units Sprout Up When a State Lets Them Grow? Evidence From California

Nicholas J. Marantz
University of California Irvine, School of Social Ecology

Christopher S. Elmendorf
University of California Davis, School of Law

Youjin B. Kim
University of California Irvine, School of Social Ecology

Since 2016, California has adopted several laws to facilitate the development of accessory dwelling units (ADUs), which are secondary units on residential parcels. This article analyzes ADU permitting in the Bay Area and southern California under the newly liberalized legal regime using data collected by the state. The analyses indicate that ADUs represent a substantial share of recent housing permits, that ADUs are typically permitted on parcels with relatively good access to jobs, and that the relationship between a neighborhood’s ethnoracial composition and the prevalence of ADU permitting varies by county. These findings provide guidance for state and local governments seeking to understand where ADUs might be permitted following the liberalization of ADU regulation.