What does ADU stand for?

ADU stands for Accessory Dwelling Unit. It is a smaller, independent home on the same lot as a primary residence, with its own kitchen, bathroom, and entrance.

What is the difference between an ADU and a JADU?

A JADU (Junior Accessory Dwelling Unit) is a unit of 500 square feet or less created within the walls of an existing single-family home. It may share a bathroom with the main house and generally requires the owner to live on the property. A standard ADU is larger, fully self-contained, and in California does not carry an owner-occupancy requirement.

Are ADUs legal to rent out in California?

Yes. California law allows ADUs to be rented as long-term housing statewide. A permitted, finaled ADU can be leased like any other rental. Most jurisdictions prohibit renting an ADU for stays shorter than 30 days.

How big can an ADU be?

Under California state standards, a detached ADU of up to 800 square feet (with limits on height and setbacks) must generally be allowed on most residential lots, and many jurisdictions permit detached ADUs up to 1,200 square feet. Local rules vary, so confirm with your city or county.

What Is an ADU?

An ADU (Accessory Dwelling Unit) is a smaller, self-contained home on the same lot as a primary residence, with its own kitchen, bathroom, sleeping area, and entrance.

ADUs are also called granny flats, in-law units, backyard cottages, casitas, or secondary units. In Los Angeles County they are a fast-growing source of legal, independent rental housing.

The three main types of ADU

Detached ADU — a standalone structure in the backyard, separate from the main house. This is the classic "backyard cottage."
Attached ADU — an addition that shares a wall with the primary home but has its own entrance and full kitchen and bath.
Conversion ADU — created by converting existing space such as a garage, basement, or attic into a legal dwelling.

A related category is the Junior ADU (JADU): up to 500 square feet, carved out of the existing walls of a single-family home, often sharing a bathroom with the main house.

What makes a unit a legal ADU?

A legal ADU has been permitted and finaled — meaning the local building department inspected the work and signed off on it. A finaled ADU is what lets you rent the unit out with confidence and what a tenant should look for. On A-du, the rental marketplace lists permit-finaled ADUs in Los Angeles County so renters know the home is legal and inspected.

Why ADUs matter in Los Angeles

California has steadily loosened ADU rules to add housing: approvals are ministerial (no discretionary hearing), agencies must act within set timelines, and owner-occupancy cannot be required for standard ADUs. The result is one of the largest ADU booms in the country, concentrated in Los Angeles County. ADUs give homeowners rental income and give renters a private, ground-level home that is hard to find in the apartment market.

Next steps: Browse ADU rentals in LA County, learn how to rent out your ADU, or explore pre-approved ADU plans.

Frequently asked questions

What does ADU stand for?: ADU stands for Accessory Dwelling Unit. It is a smaller, independent home on the same lot as a primary residence, with its own kitchen, bathroom, and entrance.
What is the difference between an ADU and a JADU?: A JADU (Junior Accessory Dwelling Unit) is a unit of 500 square feet or less created within the walls of an existing single-family home. It may share a bathroom with the main house and generally requires the owner to live on the property. A standard ADU is larger, fully self-contained, and in California does not carry an owner-occupancy requirement.
Are ADUs legal to rent out in California?: Yes. California law allows ADUs to be rented as long-term housing statewide. A permitted, finaled ADU can be leased like any other rental. Most jurisdictions prohibit renting an ADU for stays shorter than 30 days.
How big can an ADU be?: Under California state standards, a detached ADU of up to 800 square feet (with limits on height and setbacks) must generally be allowed on most residential lots, and many jurisdictions permit detached ADUs up to 1,200 square feet. Local rules vary, so confirm with your city or county.

This guide is general information, not legal advice. Confirm requirements with your city or county before building or renting an ADU.