Homeowner's Rights to Build Accessory Dwelling Units in California

Recent California laws have greatly expanded homeowners' rights to build accessory dwelling units on their single-family properties.

By , J.D. · University of Washington School of Law


Over the past few years it's become much easier for single-family property owners in California to build accessory dwelling units (ADUs, also known as in-law apartments, granny flats or backyard cottages) and junior accessory dwelling units (JADUs). JADUs are essentially units built within existing structures, e.g., bedrooms with attached bathrooms converted into separate rental units. 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 over the last five years, coupled with restraints on local control, have fostered a backyard building boom.

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 01/01/2020-01/01/2025, 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, the COVID-19 pandemic, and a super-tight housing market all combine into the perfect recipe for an ADU/JADU explosion. According to a Freddie Mac study, the number of ADU/JADU either rented or sold doubled between 2009 and 2019 — even prior to COVID-19! By all appearances, ADUs/JDUs will continue to boom.

Effective Date: March 24, 2022.