One ADU or one JADU? State law lets you build both

You have a single-family lot and a plan: convert the garage into an ADU, and carve a junior unit out of the house for a parent. Then you open your city's ADU code and hit the wall — it offers you "an ADU or a JADU." One or the other. Pick.

Here's the thing: that little word "or" is a barrier HCD keeps flagging. Under state ADU law, a single-family lot isn't capped at one accessory unit — and the state has told city after city so.

What HCD told Hermosa Beach

On December 29, 2025, HCD reviewed the City of Hermosa Beach's ADU ordinance (No. 1484) and looked hard at its unit-allowance section. The ordinance allowed "One ADU... and one JADU (or a second ADU in lieu of the JADU)." HCD's read:

"Thus, the City limits ADU and JADU development to no more than two units on a lot with a single-family primary dwelling."

That cap, HCD found, doesn't match the statute. Government Code § 66323(a) requires a local agency to "ministerially approve" — no discretion, no hearing — an application to create "One accessory dwelling unit and one junior accessory dwelling unit per lot with a proposed or existing single-family dwelling," and, separately, "[o]ne detached, new construction, accessory dwelling unit."

HCD spelled out what that combination means for a homeowner:

"This permits a homeowner... to create one converted ADU; one detached, new construction ADU; and one junior accessory dwelling (JADU)."

Read that again. On HCD's reading, the statute isn't "an ADU or a JADU." It's a converted ADU, a detached new-construction ADU, and a JADU — three accessory units alongside the primary house, for a homeowner who meets the size and setback rules.

Verified against the Hermosa Beach Ordinance Findings Letter, December 29, 2025 (HCD, Division of Housing Policy Development).

It's a pattern, not a one-off

Hermosa Beach isn't alone. HCD has flagged the same barrier in ordinance after ordinance.

Hesperia. In a June 19, 2025 findings letter, HCD reviewed Ordinance No. 2024-13, which said "Lots with an existing or proposed single-family residence may be permitted one (1) accessory dwelling, and one (1) junior accessory dwelling unit." HCD found this "limiting lots with single-family residences to one ADU and one junior accessory dwelling (JADU)" — and noted it left out the detached, new-construction ADU the statute allows on top.

Palo Alto. Years earlier, in a December 23, 2021 findings letter under the prior ADU statute (former Gov. Code § 65852.2), HCD caught the classic version: the ordinance text limited units to "an ADU or JADU." HCD pointed to the statute, which "requires an ordinance to allow 'one ADU and one JADU per lot.'"

Different cities, different years, same defect: a rule that quietly caps a single-family lot at one accessory unit, or forces an either/or choice the statute doesn't.

Why this matters at your counter

If your city's code offers "an ADU or a JADU," or caps your lot at one accessory unit, that language may be exactly the kind of barrier HCD keeps calling out. The statute's approval of these combinations is ministerial — HCD's position is that once your application meets the size and setbacks, the local agency "cannot deny" it.

Two cautions worth keeping in front of you:

• An HCD letter is HCD's position, not a court ruling. These findings letters put a city on notice and can lead HCD to notify the Attorney General, but courts are the final word on what the law requires. Hermosa Beach had until January 30, 2026 to amend its ordinance or defend it with findings.
• Your lot has its own facts. Setbacks, existing structures, fire and safety, and the specific conditions in § 66323 all matter. None of this is legal advice.

So before you accept an "or," read the current statute and verify with your jurisdiction — and, where there's real money on the line, your own counsel. The barrier printed in the code isn't always the barrier the state will let stand.

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.