ADU vs JADU in California: What Is the Difference?

ADU and JADU side by side

Both terms come from the same body of state law, Chapter 13 of Division 1, Title 7 of the Government Code (sections 66310 to 66342). Articles written a few years ago cite section 65852.2 for these rules; that is the older location of the same law, and some details inside it moved on January 1, 2026. Here is how the two unit types differ on the points owners ask about most.

• Where it can sit. An ADU can be detached, attached to the house, or converted from existing space. A JADU must be inside the walls of a single-family house, and an attached garage counts (section 66313).
• Maximum size. A detached ADU can reach 1,200 square feet; an attached ADU can reach 50 percent of the existing house (section 66314). A JADU stops at 500 square feet.
• Kitchen and bathroom. An ADU is a complete home, which in practice means its own kitchen and bathroom. A JADU needs an efficiency kitchen and may share a bathroom with the main house.
• Entrance. A JADU needs its own entry. An ADU normally has one as a matter of design.
• Parking. A JADU adds no parking requirement. For an ADU, a city may require no more than one space per unit or per bedroom, whichever is less, and none at all in several situations listed in sections 66314 and 66322.
• Impact fees. None on an ADU of 750 square feet or less, and none on a JADU of 500 square feet or less (section 66311.5).

Owner occupancy changed on January 1, 2026

State law does not let a city require the owner to live on the property for an ADU (section 66315). Before this year, a JADU came with an owner-occupancy requirement. AB 1154, effective January 1, 2026, narrowed it: under section 66333 the owner has to live on the property only if the JADU shares sanitation facilities with the main house.

Be careful with older material. The City of Los Angeles zoning memo on ADUs (ZA Memo 143, Revision 1, dated August 1, 2025) predates the change and still describes the older JADU rule. Where a local document and the statute disagree, the statute controls. A JADU with its own bathroom and its own entry is therefore the version that does not tie you to living on site.

Which part of the house can become a JADU?

Think of a JADU as a conversion of space you already own: a spare bedroom with an exterior door, a bonus room, or an attached garage. Because the statute requires the unit to be inside the single-family house, a detached garage or a pool house cannot be a JADU. Those can be ADUs.

The JADU needs a deed restriction recorded against the property, a separate entry, an efficiency kitchen, and a rental term longer than 30 days. If you are weighing a garage for either type, garage conversion permit steps in Los Angeles walks through what the city asks for.

Fees, utilities and sprinklers for each

Government Code section 66311.5 sets the fee rules for both. It bars impact fees on an ADU of 750 square feet or less and on a JADU of 500 square feet or less, and above 750 square feet an ADU's fees must be proportional to the main house. It also says a unit under 500 square feet counts as adding no assessable space for school fees.

Utility charges are a separate matter. Connection and capacity fees are not covered by the 750 square foot exemption, but an ADU converted from existing space cannot be forced to take a new utility connection or pay a related fee. On fire safety, an ADU needs sprinklers only if the main house has them, and adding an ADU cannot make the city require sprinklers in the main house (sections 66314 and 66323).

Renting, selling and short stays

A city may require ADU rentals to be for terms of 30 days or longer (section 66315), and the state-protected ADU types and JADUs must be rented for longer than 30 days. That rules out nightly rentals in most cases. Los Angeles also has its own Home-Sharing Ordinance, which caps home-sharing at 120 days a year in a host's primary residence and bars it in rent-stabilized units. The city housing department says the answer for an ADU depends on rent-stabilization status, so confirm for your address.

Selling is narrower than most owners expect. An ADU cannot be sold separately from the main house, except to a qualified low-income buyer through a qualifying nonprofit (section 66341) or under a condominium ordinance a city has chosen to adopt (section 66342).

Can you build a JADU and an ADU on the same lot?

Often yes. Section 66323 lists four ADU types a city must approve with a building permit: an ADU and JADU converted inside the house or an existing accessory structure; one new detached ADU up to 800 square feet with 4-foot side and rear setbacks; conversions of non-livable space in a multifamily building; and up to eight detached ADUs on a lot with an existing multifamily building. The city must approve any combination of them, and may not add other objective standards to those types.

A common Los Angeles pairing is a JADU made from the attached garage plus a new detached ADU in the back yard. Whether your lot supports it depends on space, utilities and fire-zone status, so treat this as a question for a feasibility check, not a promise.

How to choose between them

Pick a JADU when you want the cheapest way to create a legal rental or guest unit inside walls you already have. It adds no footprint, needs no new foundation, and carries no parking requirement. We do not print a JADU price because we found no independent source for one.

Pick an ADU when you want a unit that stands on its own: more room, a full kitchen, a detached location, or a long-term rental you do not want to share walls with. Costs and fees are laid out in ADU cost in California.

MDG Builders (CSLB #1040337) handles either type as the general contractor: the feasibility check, the plans, the permit and the schedule, with licensed subcontractors doing the trade work. The ADU construction page covers how a project runs from first call to final inspection.