California’s decade-long effort to legalize ADUs offers lessons for other US states and regions - Brookings

California's comprehensive approach to legalizing accessory dwelling units over the past decade has emerged as a potential blueprint for other states grappling with housing shortages, according to new analysis from the Brookings Institution.

The state's systematic elimination of regulatory barriers has transformed ADUs from a rarely permitted housing option into a significant component of new residential development across California communities.

ADUs, also known as granny flats, in-law units, or backyard cottages, are secondary residential structures built on single-family property lots.

California's legislative reforms have streamlined the approval process, reduced fees, and eliminated many local restrictions that previously made ADU construction prohibitively difficult.

These changes have allowed homeowners to add rental income while creating new housing stock without requiring additional land development, addressing both affordability concerns and neighborhood density goals.

The success of California's ADU legalization efforts offers valuable insights for other states and metropolitan areas experiencing housing crises.

Property developers and homeowners in California have increasingly embraced ADUs as both investment opportunities and solutions for multigenerational living arrangements.

As housing costs continue to rise nationally, the California model demonstrates how policy reforms can unlock existing residential capacity while maintaining neighborhood character, providing a roadmap that other jurisdictions are now studying for potential implementation.