Over the past eight years, California lawmakers have adopted dozens of reforms designed to make it easier for homeowners to build Accessory Dwelling Units (ADUs), which are sometimes referred to as “granny flats,” in-law units, or casitas. 

To help homeowners, building professionals, and local planners understand these changes, which are often complex and technical, the California Department of Housing and Community Development (HCD) has published an ADU Handbook, which has been expanded and revised to include the most recent legislation.

Key Takeaways:

  • ADUs are now allowed within multifamily buildings, and up to 8 detached ADUs may be built on a lot with an existing multifamily structure.
  • Owner-occupancy requirements have been permanently banned.
  • HCD now has authority over ADU enforcement.

The handbook simplifies and explains existing state ADU law and HCD policy, using plain, non-technical language and charts to lay out what property owners are legally entitled to build, and how local governments may regulate ADUs. It also lists various funding resources for homeowners, and includes a detailed timeline of ADU legislation since 2019. It’s an essential reference for homeowners, local planners, policymakers, and ADU professionals alike.