Do State Accessory Dwelling Unit Reforms Promote Multigenerational Living? Evidence from California

Bibliographic Data

ID21476463
AuthorsNicholas J Marantz (0000-0003-2565-6885, Department of Urban Planning and Public Policy, University of California, Irvine, corresponding author), Idil Tanrisever (0000-0002-2257-9071, Department of Urban Planning and Public Policy, University of California, Irvine), Jae Hong Kim (0000-0001-9365-4326, Department of Urban Planning and Public Policy, University of California, Irvine)
Year2026
Pages1-10
Publication date2026-07-02
Open AccessYes
TypeARTICLE
VenueJournal of the American Planning Association (JOURNAL)
Journal identifiersISSN: 0194-4363 • E-ISSN: 1939-0130
PublisherInforma UK Limited (PUBLISHER • GB)
DOI10.1080/01944363.2026.2681535
OpenAlexW7167100880
LanguageEN
References cited14

Problem, research strategy, and findings Multigenerational living arrangements have become more common in the United States as housing costs rise and family structures evolve. Accessory dwelling units (ADUs) could support this shift by allowing relatives to live nearby while maintaining privacy and independence, and advocates have invoked this promise to justify laws intended to facilitate ADU development. In the past decade, at least eight U.S. states have adopted such laws. We present the first large-scale, parcel-level test of this claim, linking permit records from 14 California counties, covering approximately two-thirds of the state’s population, to geocoded voter registration and consumer reference data, identifying multigenerational households from shared surnames and age differences across single-family parcels. Parcels with ADU permits are, on average, slightly less likely to be multigenerational than comparable parcels without permits, by roughly 2 to 3 percentage points after controlling for parcel and neighborhood characteristics. This negative association persists among owner-occupied parcels. This finding is sensible in light of prior research showing household characteristics associated with multigenerational living, such as lower incomes, are also associated with informal (i.e., unpermitted) ADU development.Takeaway for practice Broad ADU legalization alone does not appear to have increased multigenerational living in California. Planners seeking to promote multigenerational housing should pair by-right ADU authorization with complementary measures such as preapproved plans and alternative financing methods

State government · Housing, Finance, and Neoliberalism · Migration, Aging, and Tourism Studies · Urban, Neighborhood, and Segregation Studies

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