What Is a Junior ADU (JADU)? California Rules Explained

A unit inside the house, not beside it

A JADU turns a part of the house, often a bedroom with an adjoining bath or an attached garage, into a self-contained studio. It needs no new building and usually no new foundation. That is the point of the category: California created it so homeowners could add a home with the smallest possible project.

Gov. Code § 66313(d) defines it as a unit of no more than 500 square feet of interior livable space, contained entirely within a single-family residence, which may have its own sanitation facilities or share them with the existing structure ¹.

A JADU is not a smaller version of a regular accessory dwelling unit. It has its own article of law and its own conditions.

The JADU rules used to be in Gov. Code § 65852.22. SB 477 (Stats. 2024, ch. 7, effective 25 March 2024) moved them to Article 3 of Chapter 13, starting at § 66333. AB 1154 (Stats. 2025, ch. 507) amended § 66333, effective 1 January 2026 ².

Sources: [1]

Key takeaways

A junior ADU (JADU) is a small home of up to 500 sq ft inside a single-family house ¹.
It is a California legal category, with its own rules in Gov. Code § 66333 and after ².
It needs its own entrance and an efficiency kitchen (a simple cooking setup) ².
It may share the main home’s bathroom. If it does, the owner must live on site ².
A deed restriction bars selling it apart from the house ².
A lot can have a JADU and an ADU, which can mean three homes on one lot ⁴.

Why a JADU matters to you

A JADU is the smallest step into extra housing. You use rooms you already have. There is often no new foundation and no new roof. For many owners, that is the difference between a project they can afford and one they cannot.

It is also flexible. An adult child, a parent or a caregiver can have their own front door and kitchen while staying close. Or it can be rented for terms longer than 30 days ².

The catch is the rules. A JADU has limits a regular ADU does not, such as the deed restriction and, with a shared bathroom, owner occupancy. Know them before you start.

How a JADU project works

Step 5, the bathroom, is the choice that changes the most. The cards set the two options side by side.

Pick the space. A bedroom suite, part of a wing, or an attached garage ².
Keep it to 500 sq ft or less of interior livable space ¹.
Add a separate entrance from outside ².
Add an efficiency kitchen: a cooking appliance, a prep counter and storage cabinets ².
Decide on the bathroom. Own or shared. Shared means an inside door to the main home and owner occupancy ².
Record the deed restriction the city requires ².
Apply, build and pass inspection.

Side by side Shared bathroom or its own? What each JADU choice brings (California)

Shares the main home’s bathroom

Needs an interior door to the main living area as well as its own outside entrance
The owner must live in the JADU or the main home
Less plumbing work, so a smaller build

Has its own bathroom

Needs only its own outside entrance
No owner-occupancy rule under state law
More plumbing, and the bathroom counts toward the 500 sq ft

Both options keep the 500 sq ft cap, the efficiency kitchen, the deed restriction and rentals longer than 30 days. Gov. Code §§ 66313(d) and 66333. Source: [1] [2]

What a California JADU ordinance must require

Gov. Code § 66333 (current text read 7 October 2026), plus § 66334 on parking.
Requirement	Rule	Section
Number	One JADU per residential lot zoned for single-family homes, with a single-family home built or proposed	§ 66333(a) ²
Owner occupancy	Required only if the JADU shares sanitation; the owner may live in either part. Not required with a separate bathroom, or if the owner is a governmental agency, land trust or housing organization	§ 66333(b) ²
Deed restriction	Recorded, runs with the land: no separate sale, and limits on size and attributes	§ 66333(c) ²
Within the walls	Built inside the single-family home; enclosed uses such as an attached garage count as part of it	§ 66333(d) ²
Entrance	A separate entrance from the home’s main entrance; with a shared bathroom, also an interior entry to the main living area	§ 66333(e) ²
Efficiency kitchen	A cooking facility with appliances, and a food preparation counter and storage cabinets of reasonable size	§ 66333(f) ²
Rental term	Longer than 30 days	§ 66333(g) ²
Parking	No additional parking may be required	§ 66334(a) ³

Where a JADU can go

Space	Works as a JADU?	Why
A bedroom with its own bath	Often	Inside the house, and the bath can serve the unit
A wing or part of a floor	Often	Inside the house, if 500 sq ft or less ¹
An attached garage	Yes	California counts it as part of the house ²
A detached garage	No	It is outside the house; it would be an ADU instead
A new backyard building	No	That is a detached ADU ²
A space in an apartment building	No	JADUs are for single-family homes ²

JADU vs ADU

	Junior ADU	ADU
Where	Inside a single-family home only	Attached, detached or converted, on single-family or multifamily lots
Size	Max 500 sq ft ¹	Local limits with state floors; see ADU size
Kitchen	Efficiency kitchen	Full cooking facilities
Bathroom	May share	Its own
Owner occupancy	Only if the bathroom is shared	Not a state requirement
Impact fees	None at 500 sq ft or less ⁵	None at 750 sq ft or less; proportional above ⁵

Worked example: one lot, two extra homes

A hypothetical single-family lot in California, applying § 66323(a)(1)–(2), which require ministerial approval of combinations of units.

Unit	Form	Rule that allows it
Main house	Existing single-family home	—
JADU	A 400 sq ft bedroom suite converted inside the house, with a separate entrance and efficiency kitchen	§ 66323(a)(1) with Article 3 ⁴ ²
ADU	A new detached unit in the yard with 4 ft side and rear setbacks (the city may cap it at 800 sq ft)	§ 66323(a)(2) ⁴

The result is three homes on one single-family lot, approved without a hearing. The JADU uses no yard and, at 500 sq ft or less, carries no impact fee under § 66311.5(c)(1) ⁵.

Where you will see the JADU label

On the permit form, as a separate box from ADU.
On the deed, as a recorded restriction that stays with the property ².
On a lease, which must be for more than 30 days ².
On the floor plan, where the 500 sq ft limit and the efficiency kitchen are shown.
On a fee notice. In California there is no impact fee for a unit this small ⁵.

Costs and what drives them

No price is given here, because the work varies so much. A bedroom suite with a bath may need only a door, a counter and a cooking appliance. A garage may need a new floor, insulation and plumbing.

The drivers are the entrance, the kitchen, the bathroom choice and any code upgrades. Fees are light: California bars impact fees at this size ⁵, and the city may not require extra parking ³. See the numbers on JADUs built so far and the ADU cost hub.

Benefits and limits of a JADU

What it does well

Uses space you already have, so the project is small.
No extra parking may be required ³.
No impact fee at 500 sq ft or less ⁵.
Can sit alongside a full ADU on the same lot ⁴.

Where it falls short

Capped at 500 sq ft ¹.
Only an efficiency kitchen is required, so it may feel small for long stays.
A shared bathroom means the owner must live on site ².
A recorded deed restriction stays with the house ².

Common misreadings

Myth Every JADU requires the owner to live on site.: Reality Only when the JADU shares the bathroom. With its own bathroom, § 66333(b) does not require owner occupancy ².
Myth A JADU can be a separate backyard building.: Reality No. It must be within the walls of the single-family home; a separate building is a detached ADU ².
Myth A JADU needs a full kitchen.: Reality No. The law requires an efficiency kitchen: cooking appliance, prep counter and storage ².

Outside California

The JADU is a California statutory category. Other states and cities may allow an internal unit under names such as accessory apartment, with their own size and owner-occupancy rules, or may treat it as a regular ADU. Check the state summary first.

What to ask before you start

Is my space 500 sq ft or less once measured as livable space?
Where will the outside entrance go?
Will the unit have its own bathroom, or share mine?
What deed restriction does my city use, and what does it say?
How will I handle owner occupancy if I share the bathroom and later move?
Would a full ADU suit my goal better? Try the type selector.

Checklist for a junior ADU

Confirm the lot is zoned single-family and has a single-family home ².
Measure the space and stay at or under 500 sq ft.
Plan the separate entrance.
Plan the efficiency kitchen: appliance, counter, cabinets.
Decide own or shared bathroom.
Read the deed restriction before you sign it.
Apply, build and pass final inspection.
Use leases longer than 30 days.

Go deeper

Accessory Dwelling Unit: An accessory dwelling unit (ADU) is a second, self-contained home on a lot that already has, or will have, a main house or apartment building, with its own space to live, sleep, cook, eat and wash.
Attached ADU: An attached ADU is an accessory dwelling unit built onto the main home, sharing at least one wall with it, but with its own entrance, kitchen and bathroom so it works as a separate home.
Garage Conversion ADU: A garage conversion ADU is an accessory dwelling unit created by turning an existing garage, attached or detached, into a complete home with its own kitchen, bathroom, entrance and living space.
ADU Owner-Occupancy Requirement: An ADU owner-occupancy requirement is a local rule that the property owner must live in either the main house or the accessory unit, so that both units cannot be rented to other people at the same time.
ADU Kitchen: An ADU kitchen is the permanent cooking area that, together with a place to sleep and a bathroom, makes an accessory dwelling unit a separate home rather than an extra room.
ADU Bathroom: An ADU bathroom is the toilet, sink and tub or shower that serve an accessory dwelling unit, which California law calls its sanitation facilities.
Converted ADU: A converted ADU is an accessory dwelling unit made from space that already exists, such as a garage, basement, attic, spare wing or shed, instead of a new building.
California ADU Law: California ADU law is the set of state statutes, now in Chapter 13 of the Government Code (Sections 66310 to 66342), that tells every city and county in California what it must allow for accessory dwelling units and junior ADUs, and what it may not require.

Also referenced from: Accessory Dwelling Unit, Attached ADU, Garage Conversion ADU, Basement ADU, Converted ADU, ADU Size, ADU Bedroom, ADU Bathroom, ADU Kitchen, ADU Accessibility, California ADU Law, ADU Owner-Occupancy Requirement, ADU Utility Connection, ADU Sewer Lateral, Separate Utility Meter, ADU Rental Agreement, Short-Term Rental ADU, Long-Term Rental ADU

Questions about junior adu

What is a JADU?

A JADU, or junior accessory dwelling unit, is a California unit of up to 500 square feet built entirely inside a single-family home, with its own entrance and an efficiency kitchen. It may share the main home’s bathroom.

What is the difference between an ADU and a JADU?

A JADU is limited to 500 square feet, must be inside a single-family home, needs only an efficiency kitchen and may share a bathroom. An ADU can be attached or detached, has a full kitchen and bathroom, and follows different size rules.

Can I have both an ADU and a JADU?

Yes. California law requires ministerial approval of one ADU and one JADU per single-family lot in the combinations set out in Gov. Code § 66323(a), for example a JADU inside the house plus a new detached ADU.

Does a JADU need its own bathroom?

No. A JADU may share sanitation with the main home. If it does, the owner must live in the house or the JADU, and the JADU needs an interior entry to the main living area.

Can I rent out a JADU?

Yes, for terms longer than 30 days under Gov. Code § 66333(g). A recorded deed restriction bars selling it separately from the house.

Can a JADU be in a garage?

Yes, if the garage is attached. California counts an attached garage as part of the single-family home for a JADU. A detached garage is outside the house, so a unit there would be a regular ADU instead.

Does a JADU need a full kitchen?

No. California requires an efficiency kitchen: a cooking facility with appliances, a food preparation counter and storage cabinets of reasonable size. The law does not require a full kitchen.

Does a JADU need parking?

No. California law says a city may not require additional parking for a junior ADU. That is one reason a JADU is often the simplest unit to add.

Can I sell a JADU separately from my house?

No. California requires a recorded deed restriction that bars selling the JADU apart from the single-family home. The restriction runs with the land, so it binds future owners too.

Sources

California Legislature, Gov. Code § 66313 (as amended by SB 543, eff. 1 Jan 2026), retrieved October 7, 2026.
California Legislature, Gov. Code § 66333 (formerly § 65852.22; amended by AB 1154, eff. 1 Jan 2026), retrieved October 7, 2026.
California Legislature, Gov. Code § 66334, retrieved October 7, 2026.
California Legislature, Gov. Code § 66323 (as amended by SB 543, eff. 1 Jan 2026), retrieved October 7, 2026.
California Legislature, Gov. Code § 66311.5 (formerly § 66324; renumbered by SB 543), retrieved October 7, 2026.

Expert review

Written by the HyreADU Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.

How the numbers were checked: Every JADU rule was read in Gov. Code §§ 66313, 66323, 66333, 66334 and 66311.5 on leginfo.legislature.ca.gov on 7 October 2026. Education, not legal advice: your city’s JADU ordinance applies these rules.

Suggest a correction. We fix errors and say what changed.