Homeowner's Rights to Build Accessory Dwelling Units in California

Hoping to build a backyard cottage or a separate living suite in or around your California home? The law might be on your side.

By , J.D. ● University of Washington School of Law
Updated 7/26/2024

Single-family property owners in California who want to build accessory dwelling units and junior accessory dwelling units (JADUs) have an easier time than those in many other states.

Prior to 2017, local jurisdictions often used confusing and burdensome permitting requirements to impede ADU/JADU construction. Many towns banned garage conversions, or forced owners to continue residing on converted properties. But statewide ADU/JADU standards enacted in recent years, coupled with restraints on local control, have fostered a backyard building boom.

What Are ADUs and JADUs?

ADUs are separate units built on a property, also known as in-law apartments, granny flats, and backyard cottages. JADUs are essentially units built within existing structures, e.g., bedrooms with attached bathrooms converted into separate rental units.

What Guidelines Must Local Jurisdictions Follow in Permitting an ADU/JADU?

Under California's statewide standards:

  • Homeowners are allowed (in most cases) to build one ADU and one JADU per lot.
  • However, local jurisdictions must use objective measures when reviewing ADU/JADU applications. And if a local jurisdiction fails to act on a completed application within 60 days, the application is deemed "approved." (CA Gov. Code, § 65852.2.)
  • Local agencies can't make homeowners "mitigate" (i.e., relocate elsewhere on the property) parking spaces lost to garage or parking structure conversions, or require setbacks for those conversions.
  • From 01/01/2020 to 01/01/2025, a local agency can't make the homeowner live on (i.e., "owner occupy) the property as a condition of issuing a permit.
  • ADUs up to 749 square feet are exempt from local impact fees (fees charged to reimburse increased strains on local infrastructure and services). Larger ADUs are subject to fees, but those fees must be proportional in amount (by square foot) to the primary dwelling unit. (CA. Gov. Code, § 65852.2.)
  • No maximum square footage requirements can be imposed on ADUs less than 850 square feet, or on two-plus bedroom units measuring less than 1,000 square feet.
  • JADUs can be built inside proposed or existing single-family residences, and JADU design restrictions have been eased (JADUs can now share bathrooms with the main unit, for example). (CA. Gov. Code § 65852.22.)
  • Local agencies must allow JADUs even when no local ordinance expressly authorizes those structures. (CA Gov. Code § 65852.2.)
  • The powers of homeowner associations and related private entities have also been restrained: Covenants, conditions, and restrictions (CC&Rs) that prohibit or unreasonably restrict ADU/JADU construction or use on single-family residential lots are unenforceable. (Civ. Code, §§ 4740, 4751.)
  • Other recent provisions of state law grant owners five years to bring substandard ADUs into compliance, and beef up enforcement so that the state can make sure that localities are following the new law.
  • Importantly, the statewide standards are meant as "overlay" regulations, meaning local codes generally still apply. Local agencies can continue to impose reasonable limits on construction/design based on traffic flow and other public safety considerations.

Is This a Good Time to Build an ADU/JADU in California?

Relaxed regulations and a super-tight housing market combine into the perfect recipe for an ADU/JADU explosion. Consult an attorney if you have questions about what's legally possible in your area of California.