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San Diego ADU Planner

JADU vs ADU in San Diego

Updated

JADU vs ADU comes down to size and location. A junior accessory dwelling unit (JADU) is a small unit carved out of your existing home. An accessory dwelling unit (ADU) can be attached, detached, or converted from another structure, and it can be much larger. Here is how they compare under the City of San Diego's current rules and recent state law.

Cutaway illustration of a house with a junior ADU room inside it
A JADU sits inside the main home.

Side by side

JADU ADU
Size 150 to 500 sq ft [1] 150 to 1,200 sq ft for new attached or detached [2]
Where Entirely inside a single-family home [1] Attached, detached, or converted [2]
Parking None required [2] None required outside the Coastal Overlay Zone, with some exceptions [2][1]
Short-term rental Not allowed; rentals must be longer than 30 days [2] Not allowed; leases at least 31 days [2]
Owner lives on site Only if it shares sanitation with the main home [3] Not required [2]
Impact fees Exempt at 500 sq ft or less [3] Can apply [4]

Size and location

A JADU must be 150 to 500 square feet and sit entirely inside a single-family home [1]. Since the City's Housing Action Package 2.0, JADUs cannot be built inside detached garages or inside other ADUs [3].

A new attached or detached ADU can be 150 to 1,200 square feet [2]. Converting an existing structure into an ADU is not held to the 1,200 square foot limit [2].

How many you can have

On a single-dwelling lot, the City allows one main home, one attached or detached ADU, one converted ADU, and one JADU [2]. So a JADU does not use up your ADU. You may be able to have both.

Owner occupancy and renting

Since January 1, 2026, state law requires the owner to live on site with a JADU only if the JADU shares sanitation facilities, such as a bathroom, with the main home [3]. For an ADU, the City says the owner is not required to live on site [2].

Neither unit can be a short-term rental. JADUs must be rented for more than 30 days, and ADUs may not be rented for less than 31 days in a row [2].

Fees

State law now exempts JADUs of 500 square feet or less from impact fees [3]. Plan check and inspection fees still apply. The City's fee schedule groups attached ADUs and JADUs up to 1,100 square feet in one fee row [4]. See our ADU cost guide for the amounts.

Which one fits your plans?

A JADU can make sense if you have a spare bedroom or wing to convert, want a lower-cost project, and plan to stay in the home. An ADU fits better if you want a larger, fully separate unit for a tenant or family member, or a unit you might later sell. The City now allows most ADUs to be sold separately as condominiums [5].

FAQ

Can I have both a JADU and an ADU?

Yes, on a single-dwelling lot in the City of San Diego. The City allows one attached or detached ADU, one converted ADU, and one JADU along with the main home [2]. Your lot, layout, and utilities still need to work, so ask a contractor to check.

Does a JADU need its own bathroom?

Not necessarily, but it changes the rules. Since January 1, 2026, the owner must live on site only if the JADU shares sanitation facilities with the main home [3]. A JADU with its own bathroom avoids that owner-occupancy rule.

Request a quote for a JADU or ADU from an independent local contractor. More rules are in our San Diego ADU rules and permits guide.

We're a referral service, not a contractor, and independent contractors may pay us for referrals.

Sources

  1. City of San Diego Development Services, "Accessory Dwelling Unit/Junior Accessory Dwelling Unit," no date shown. Fetched 2026-11-11. https://www.sandiego.gov/development-services/news-programs/programs/companion-junior-units
  2. City of San Diego Development Services, "Information Bulletin 400: Accessory Dwelling Unit/Junior Accessory Dwelling Unit," January 2026. Fetched 2026-11-11. https://www.sandiego.gov/development-services/forms-publications/information-bulletins/400
  3. City of San Diego Development Services, "Regulatory Updates," no date shown. Fetched 2026-11-11. https://www.sandiego.gov/development-services/regulatory-updates
  4. City of San Diego Development Services, "Information Bulletin 501: Fee Schedule for Construction Permits," August 2026. Fetched 2026-11-11. https://www.sandiego.gov/development-services/forms-publications/information-bulletins/501
  5. City of San Diego Development Services, "Public Notice: Information Bulletin 400 Updates," August 27, 2025. Fetched 2026-11-11. https://www.sandiego.gov/sites/default/files/2025-08/dsd_ib400_adu.pdf