JADU Owner-Occupancy Now Turns on One Thing: The Bathroom

You're carving a junior unit out of your house — a JADU, built inside the existing walls — and you want to rent it out. Maybe you don't plan to live in the main house forever. Then you read your city's ADU code and hit the wall: the owner has to occupy the property. For a JADU, that line used to be routine.

Here's the thing: since the 2025 changes to state ADU law, the owner-occupancy rule for a junior unit turns on a single fact — whether the JADU shares a bathroom with the main house.

What the 2025 change did

State law now ties JADU owner-occupancy to shared sanitation. HCD described the change plainly when it walked the City of Mountain View through the new rules:

"Specifies that if a JADU has shared sanitation facilities with the primary structure, owner-occupancy will be required. If the JADU does not have shared sanitation facilities, owner-occupancy will not be required (Gov. Code, § 66333, subd. (b))."

The hinge is Government Code § 66333(b). As HCD put it to the City of San Carlos, "as of January 1, 2026, the owner-occupancy requirement only applies if the JADU has shared sanitation facilities with the existing structure." A junior unit with its own bathroom — separate sanitation — no longer carries an owner-occupancy condition on HCD's reading.

San Diego County: the "considered legal only" clause

On July 7, 2026, HCD reviewed San Diego County's ADU ordinance and faulted its JADU owner-occupancy language. The ordinance read:

"The JADU shall be considered legal only so long as either the primary residence, or the ADU, is occupied by the owner of record of the property…"

HCD's position: that sweeps wider than the statute allows. Section 66333(b), the letter says, "requires owner-occupancy only '[i]f the junior accessory dwelling unit has shared sanitation facilities with the existing structure…'" So HCD told the County to delete the "considered legal language" and "specify that owner-occupancy is only required in the case of shared sanitation."

Verified against HCD's ADU Ordinance Findings Letter to San Diego County, dated July 7, 2026, quoting Gov. Code § 66333(b).

Same rule, city after city

This isn't one county's slip. HCD flagged the same blanket owner-occupancy language across a run of 2026 ordinance reviews:

• La Quinta required "Owner-occupancy in the single family residence in which the junior accessory dwelling unit is permitted is required." HCD pointed to the shared-sanitation limit in § 66333(b).
• Larkspur's code said "The Owner shall reside in either the remaining portion of the primary residence or the newly created JADU." HCD's read: the statute "only requires owner-occupancy '[i]f the junior accessory dwelling unit has shared sanitation facilities with the existing structure.'"
• Napa County carried a "must occupy" clause and Colusa a "considered legal only" clause; HCD told each to limit the requirement to the shared-sanitation case.

Two more JADU traps in the same letter

San Diego County's letter didn't stop at owner-occupancy. HCD faulted two other JADU rules worth knowing:

• The ordinance said, "If a JADU is to be attached to an ADU, ministerial review is unavailable." HCD's position: "a unit may not be denied due to its incidental adjacency to an ADU," and it told the County to remove the section.
• The ordinance required replacement parking when a garage becomes a JADU. HCD quoted Government Code § 66334: "A junior accessory dwelling unit ordinance adopted pursuant to Section 66333 shall not require additional parking as a condition to grant a permit."

What to do with it

If your JADU permit is stalled over an owner-occupancy condition, the question to ask is narrow: does the junior unit share sanitation facilities with the house, or have its own? If it's separate, the state's baseline no longer supports a blanket owner-occupancy requirement.

One caution: HCD's letters are its enforcement position, not a court ruling — courts have the last word, and only a housing-element decertification is self-executing. So confirm with your building department or your attorney before you rely on this against a specific project. This isn't legal advice. But the statutory line is now clear, and HCD is enforcing it.

What CrossBeam does with it

When the letter lands on your desk, CrossBeam turns it around the same day: what each item is actually asking, the code or law behind it, and a written response you can hand to your team or your attorney — the back-and-forth that used to eat weeks, done in a couple of hours.