Junior Accessory Dwelling Unit (JADU)

What Is a Junior Accessory Dwelling Unit?

A junior accessory dwelling unit (JADU) is a small home created inside an existing or planned single-family house, for example by converting a bedroom or an attached garage. California law defines it as a unit of no more than 500 square feet of interior livable space, “contained entirely within a single-family residence.”

The term comes from California law. Other places may allow similar units inside a house under other names, such as interior ADU, each under its own rules.

How It Works

Under California Government Code § 66333, a city or county may adopt an ordinance allowing JADUs in single-family zones. The ordinance must include several standard terms:

• One per lot. A single-family lot may have one JADU.
• Inside the house. The JADU must be built within the walls of the home. Enclosed spaces such as an attached garage count as part of the home.
• Separate entrance. The unit needs its own entrance. If it lacks a separate bathroom, it also needs an interior door into the main living area.
• Efficiency kitchen. The unit must have a cooking facility with appliances, a food preparation counter and storage cabinets.
• Deed restriction. A recorded restriction bars selling the JADU separately from the house and limits its size and features.
• No short stays. Any rental must be for a term longer than 30 days.

Owner-occupancy rules changed recently. Under Assembly Bill 1154, enacted in 2025 and effective January 1, 2026, the owner must live on site only when the JADU shares bathroom facilities with the main house. The owner may live in either part of the home. Owner occupancy is not required when the JADU has its own bathroom, or when the owner is a government agency, land trust or housing organization.

JADU vs. ADU

A full accessory dwelling unit is a complete independent home and can be a separate building.

Why It Matters for Workforce Housing

JADUs reuse space inside an existing house, so creating one does not require new land or a new building. They can house a relative, a caregiver or a renter. However, they are small, and state law does not restrict their rents or the incomes of the people who live in them. They add modest, flexible capacity rather than guaranteed affordable housing.