What you can build

Junior ADUs (JADUs): the small unit inside your house

Checked against state laws and official agency sources · Last reviewed October 9, 2026

What counts as a junior ADU

California law defines a junior ADU as "a unit that is no more than 500 square feet of interior livable space in size and contained entirely within a single-family residence." It may have its own bathroom or share one with the house.

• Inside the house only. A JADU must be built within the walls of the existing or proposed single-family home. Attached garages and other enclosed spaces in the home count as part of the house. A JADU is not allowed in a detached garage or other accessory structure.
• One per lot. Only one JADU is allowed per lot zoned for single-family homes with a house on it or planned. HCD says that holds even if a lot has several detached houses.
• Single-family only. A JADU can't be built on a multifamily lot. A duplex on one lot counts as multifamily. A "half-plex" (two homes on separate lots sharing a wall) can have one JADU in each half.

[1][2][3]

Size limit

The cap is 500 square feet of interior livable space: space meant for living, sleeping, eating, cooking or sanitation. The law changed to this measure on January 1, 2026.

A JADU can't use the extra 150 square feet that state law allows for some ADUs converted from accessory structures. That allowance is only for ADUs created from existing accessory structures, and only for getting in and out. [1][3]

Entrance, kitchen and bathroom

• Entrance: A JADU must have its own entrance, separate from the house's main entrance.
• Bathroom: It may have its own bathroom or share the house's. If it has no bathroom of its own, it must also have an interior door into the main living area.
• Kitchen: It needs an efficiency kitchen with "a cooking facility with appliances" and "a food preparation counter and storage cabinets that are of reasonable size in relation to the size of the junior accessory dwelling unit."

HCD says cities can't be stricter than that kitchen definition. They can't require particular counter or cabinet sizes, electrical or gas connections, or appliance types, and a 220V circuit is not required.

A JADU no longer has to be made from an existing bedroom, and it doesn't need an interior connection to the house when it has its own bathroom. [2][3]

Owner occupancy and the deed restriction

Owner occupancy (from January 1, 2026): If the JADU shares a bathroom with the house, the owner must live on the property, either in the rest of the house or in the JADU. If the JADU has its own bathroom, owner occupancy can't be required. It also doesn't apply when the owner is a government agency, land trust or housing organization.

Deed restriction: A city's JADU ordinance must require you to record a deed restriction that runs with the land and is filed with the permitting agency. It must include:

• a ban on selling the JADU separately from the house, enforceable against future buyers
• a limit on the JADU's size and features that matches state law

Unlike a JADU, a regular ADU can't be given an owner-occupancy rule or an affordability deed restriction. [2][3][4]

Fees, utilities, parking and fire sprinklers

• Impact fees: No impact fees on a JADU of 500 square feet of interior livable space or less.
• School fees: A JADU under 500 square feet is not treated as adding assessable space for school fee purposes.
• Utilities: For water, sewer or power service, including connection fees, a JADU is not a separate or new dwelling unit. A JADU created inside the house can't be required to get its own utility connection or pay a related connection fee or capacity charge, unless it is built with a new single-family home. A utility can still apply a fee or rule that covers all single-family homes the same way.
• Parking: A city can't require extra parking for a JADU, even when it is converted from an attached garage.
• Fire sprinklers: If the house doesn't need sprinklers, the JADU doesn't either, and adding a JADU can't trigger a sprinkler requirement. For fire and life-safety rules, a JADU is not a separate or new dwelling unit.
• Permit and inspection fees: A city may charge fees to cover its permit costs and may charge for an inspection to check the JADU meets building standards.

[3][5][6][7][8][9][10]

Getting a permit

A JADU permit is reviewed ministerially, meaning by staff against objective rules, with no hearing.

• The permitting agency must tell you within 15 business days whether your application is complete, and list anything missing.
• It must approve or deny a complete application within 60 days if there is already a house on the lot. If you apply together with a new house, it can wait to decide the JADU until it decides the house.
• A denial must come with a full written list of what's wrong and how to fix it. You can appeal in writing, and the city must decide the appeal within 60 business days.

If your city has no JADU ordinance, it still has to approve a JADU that meets state law. If a city doesn't send its JADU ordinance to HCD within 60 days of adopting it, or doesn't answer HCD's findings within 30 days, the ordinance is void and only state law applies. A city can't deny a JADU because of existing zoning nonconformities, code violations or unpermitted structures that aren't a health and safety threat and aren't affected by the work. [3][8][11][12][13]

Junior ADU or regular ADU?

• Where: A JADU goes inside a single-family home, including an attached garage. An ADU can be inside the house, attached or detached, including in garages and other accessory structures, on single-family or multifamily lots.
• Size: A JADU is capped at 500 square feet of interior livable space. For an ADU, cities must allow at least 800 square feet, and any maximum they set can't be below 850 square feet (1,000 square feet with more than one bedroom).
• Bathroom and kitchen: A JADU may share the house's bathroom and needs only an efficiency kitchen. An ADU must have "permanent provisions for living, sleeping, eating, cooking, and sanitation."
• Owner occupancy: Required for a JADU only when it shares a bathroom. It can't be required for an ADU.
• Impact fees: None for a JADU up to 500 square feet, and none for an ADU up to 750 square feet.

You don't have to choose. On a single-family lot, a city must approve one ADU or JADU inside existing space, one JADU, and one new detached ADU together. HCD says that means one converted ADU, one JADU and one detached ADU on the same lot. See California ADU rules for the full state picture.

Coming January 1, 2027: AB 956 (2026) will require cities to approve two new detached ADUs on a single-family lot instead of one. A city won't have to approve a JADU on a lot where two detached new ADUs have been built under that rule. AB 956 is a regular (non-urgency) 2026 law, so it takes effect on January 1, 2027. [1][2][3][4][5][10][14][15][16]

Renting and legalizing a JADU

You can rent a JADU, but a rental must be for a term longer than 30 days, so short-term rentals are out. This rule was added by AB 1154, effective January 1, 2026.

If you have a JADU built without permits before January 1, 2020, the city generally can't deny a permit to legalize it because it violates building standards or JADU rules. The exception is where a fix is needed to meet the state's health and safety standards for substandard buildings.

City rules on JADUs vary. Check your city's guide: Los Angeles, San Diego, San Jose, San Francisco, Sacramento, Oakland, Long Beach, Berkeley or Pasadena. [2][3][17]

Questions people ask