What is a JADU (Junior ADU) in California?

A JADU (Junior Accessory Dwelling Unit) is a small secondary unit created within the walls of an existing single-family home, capped at 500 square feet. JADUs can include an efficiency kitchen and must share or have access to a bathroom with the main house. They are the lowest-cost ADU option.

How much does a JADU cost in California?

JADUs typically cost $30,000–$80,000 in California, making them the most affordable ADU option. Costs depend on whether the space needs new plumbing, electrical upgrades, or a separate entrance. Converting existing finished space is cheapest; unfinished basements or attics cost more.

What is the difference between a JADU and an ADU?

A JADU is capped at 500 sq ft and must be within the existing structure of the primary home. A standard ADU can be up to 1,200 sq ft and can be detached, attached, or converted. JADUs must share or adjoin a bathroom with the main house; ADUs require their own full bathroom and kitchen.

Do I need owner-occupancy for a JADU in California?

Owner-occupancy rules for JADUs have changed under recent California legislation. As of 2025, California has largely removed owner-occupancy requirements for both ADUs and JADUs, though some local ordinances may still apply. Check with your city for current local rules.

JADU (Junior ADU) Guide for California: 2026 Rules & Benefits

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What Is a Junior ADU (JADU)?

A Junior Accessory Dwelling Unit (JADU) is a small residential unit created within the existing footprint of a single-family home. JADUs are capped at 500 square feet and must include a cooking facility (can be an efficiency kitchen — sink, counter, small appliance outlet, and a place for a portable cooking device).

JADUs are the fastest, cheapest, and easiest type of ADU to build in California.

JADU Rules in California (2026)

Maximum size: 500 square feet.
Location: Must be within the existing or proposed footprint of the primary residence (including attached garages).
Entrance: Must have a separate exterior entrance from the main dwelling.
Kitchen: An efficiency kitchen is required (can be minimal — no full stove required).
Bathroom: Can share a bathroom with the primary residence OR have a separate one.
Owner occupancy: The homeowner must live in either the main house or the JADU (unlike regular ADUs, JADUs do require owner-occupancy).
Parking: No additional parking required.
Deed restriction: A deed restriction is recorded stating the property cannot be sold separately from the primary residence.

JADU vs. Regular ADU

Feature	JADU	ADU
Max size	500 sq ft	1,200 sq ft
Location	Within existing home	Attached or detached
Cost	$50K – $100K	$150K – $450K
Owner occupancy	Required	Not required (post-2020)
Can have both?	Yes — California allows one ADU + one JADU on single-family lots

Best Use Cases for a JADU

Converting a spare bedroom + adding kitchenette: Minimal construction, maximum return.
Attached garage conversion: Reframe the garage space into a studio apartment within the home's footprint.
Aging parent suite: Keep family close with an independent-but-connected living space. Read our aging-in-place guide.
Supplemental income on a budget: $50K–$100K investment generating $1,200–$2,000/month.

JADU Cost Breakdown

Efficiency kitchen installation: $8,000 – $15,000
Bathroom (new or upgrade): $10,000 – $25,000
Separate entrance: $3,000 – $8,000
Insulation / soundproofing / fire separation: $5,000 – $12,000
Permits and plans: $1,000 – $4,000
Finishes: $10,000 – $25,000

Interested in a JADU? Get matched with contractors experienced in JADU conversions.

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