If you’re shopping for an investment property in unincorporated LA County because of what you can add to the lot, there’s a draft rule change you should know about. In May 2026, LA County Planning released a proposed 2026 ADU Ordinance Amendment. The biggest piece for investors: it would use authority the state gave counties to limit ADUs on lots created through SB 9 and SB 1123 lot splits.
It is not law yet. The county calls it a draft under evaluation, and no hearings have been scheduled. But if your plan is “split the lot, then stack ADUs on both pieces,” this draft tells you exactly where the county is headed. Here’s what it says, what it doesn’t change, and how to count your doors before you write an offer.
Who this affects
Only properties in unincorporated LA County. That’s the land the county governs directly, not the 88 cities. Think communities like Altadena, East Los Angeles, Hacienda Heights, Rowland Heights, unincorporated Whittier, West Carson and Lennox. If the property is inside a city like Long Beach, Lakewood or Downey, that city’s own ADU and SB 9 rules apply instead. My Long Beach SB 9 guide is a good example of how different a city’s rules can look.
Two quick checks: the listing’s “city” field isn’t reliable, so confirm jurisdiction on the parcel itself. And in Altadena, parts of the Eaton fire area have separate restrictions. LA County’s current SB 9 implementation memo notes that Executive Order N-32-25 suspends SB 9 in certain areas inside the Palisades and Eaton fire boundaries.
What the draft would do
The county’s Lot Splits and ADUs explainer (dated May 4, 2026) sorts subdivisions into three buckets:
| How the lot was split | What the draft allows | ADUs and JADUs |
|---|---|---|
| SB 9 urban lot split (2021) | Two new parcels, each at least 1,200 sq ft, one at least 40% of the original lot | Count toward a cap of 2 units per parcel: two primary homes, or one primary home plus one ADU or JADU |
| SB 1123 small-lot subdivision (2024) | Up to 10 lots, each with a primary home | Prohibited |
| Standard county subdivision (Title 21, with a public hearing) | No new caps | Standard ADU allowances still apply |
The county’s amendment summary lists a few other items too: clarifying how county ADU rules line up with state law, refining the definition of publicly dedicated open space, and clarifying standards for state-exempt detached ADUs on multifamily lots.
Why the county can do this
State law gives local agencies an opt-out on both kinds of split.
- SB 9: under Government Code 66411.7, a city or county can cap each parcel created by an urban lot split at two units, and ADUs and JADUs count toward that cap. The state’s HCD SB 9 fact sheet summarizes it.
- SB 1123: this law expanded the SB 684 starter-home process to vacant single-family lots up to 1.5 acres starting July 1, 2025. It also says a local agency isn’t required to permit an ADU or JADU on the new parcels. See this Burke, Williams & Sorensen summary of SB 1123.
So the draft isn’t the county inventing a new limit. It’s the county choosing to use limits the state already put on the table.
What it does not change
This is the part most headlines will skip, and it’s the part that matters most for buy-and-hold investors.
- A regular single-family lot keeps its ADU options. The county’s single-family home guide says the amendment “does not reduce the ADU or JADU opportunities available on a single-family lot.”
- SB 9 without a split is untouched. Under the county’s current SB 9 memo, the two-unit development path allows two primary homes, and ADUs and JADUs are allowed on top of that under state ADU law.
- No owner-occupancy for ADUs. That stays the same. A JADU that shares a bathroom with the main house still needs owner occupancy. The 3-year owner-occupancy affidavit for SB 9 lot splits also stays.
- No short-term rentals. ADUs, JADUs and SB 9 units still have to be rented for more than 30 days.
One more thing worth knowing: for SB 9 lot splits, the county’s current memo already counts ADUs and JADUs inside the two-unit cap per parcel. For that path, the draft mostly writes into the ordinance what the county is already doing. The bigger new piece is the ADU ban on SB 1123 lots. If you’ve seen the same rule in Orange County, I explain it in the two-unit maximum per parcel most people misread.
Count the doors: four ways to use the same lot
Here’s an illustrative 7,500 sq ft single-family lot in unincorporated LA County with a 3-bed house in front. Rents are rough placeholders to show the shape of the math, not a market study.
| Path | Max units | Owner-occupancy? | Sell a unit separately? | Illustrative gross rent |
|---|---|---|---|---|
| No split: house + ADU + JADU | 3 | Only if the JADU shares a bathroom | No | About $7,400/mo |
| SB 9 two-unit development (no split) + ADU + JADU | 4 | Only if the JADU shares a bathroom | No | About $10,400/mo |
| SB 9 urban lot split | 4 (2 per parcel, ADUs included) | Yes, 3-year affidavit | Yes | About $11,000/mo |
| SB 1123 (vacant lots only) | Up to 10 primary homes, 0 ADUs | No | Yes | Depends on density; a builder play |
Rent assumptions: existing 3-bed house $3,700, 800 sq ft 2-bed ADU or SB 9 unit $3,000, JADU $1,700, new 3-bed SB 9 home $3,700. Pull real comps for the exact street before you underwrite. For how much unit size moves rent, see 500 vs. 800 sq ft SB 9 units and what each one rents for.
The takeaway: for an investor who won’t live on the property, the draft doesn’t touch the best path. The no-split SB 9 route still gets you two primary homes plus an ADU and a JADU on one parcel with no owner-occupancy affidavit. That’s the same play I break down in how investors are engineering $10K-a-month triplexes in LA County with SB 9 and an ADU.
The split only wins if you’ll live there for three years and want the option to sell or refinance one parcel later. Keep in mind an SB 9 home and an ADU don’t appraise the same way. I explain why in an SB 9 unit is not an ADU, and the difference matters at appraisal, and what back parcels actually sell for in how SB 9 properties get valued in LA County.
Where AB 956 fits in
The county wrote this draft before Governor Newsom signed AB 956 on September 29, 2026. Starting January 1, 2027, AB 956 requires ministerial approval of up to two new detached ADUs on a lot with a single-family home. Cities and counties can cap each at 800 sq ft, with side and rear setbacks of no more than 4 feet. If two detached ADUs are built that way, the agency doesn’t also have to approve a JADU.
For a no-split single-family lot, that could mean two full-size detached rentals instead of one ADU plus a small JADU. Expect the county’s final ordinance to account for it. It’s one more reason to read the final version before you lock in a plan.
Status and timeline
- May 4, 2026: draft explainers released. The county held a public webinar on May 21.
- July 2026: the county’s project page moved to a “Draft Evaluation Phase” while staff review feedback.
- Next: public hearings at the Regional Planning Commission and then the Board of Supervisors. As of this writing, none are scheduled.
The county is clear that the draft materials “do not carry the force of law.” Current county and state rules govern any ADU or SB 9 project you file today. Want to comment or get updates? Contact LA County Planning’s Housing Policy Section at (213) 974-6417 or housing@planning.lacounty.gov.
What to do if you’re buying now
- Confirm the jurisdiction. Unincorporated county or a city? That decides which rulebook applies.
- Underwrite the no-split path first. It’s the one the draft leaves alone and the one that works for non-owner-occupants.
- If you’re counting on a split, count ADUs inside the 2-unit cap. Don’t model a split plus ADUs on both parcels.
- If you’re looking at a vacant lot for SB 1123, assume zero ADUs. Price the land on primary homes only.
- Check that SB 9 still applies to the parcel. Fire zones, historic status, tenant history and court rulings all matter. Start with is SB 9 still valid in 2026? and the county’s SB 9 page.
FAQ
Is LA County’s 2026 ADU ordinance amendment in effect?
No. It’s a draft under evaluation. No public hearings have been scheduled, and current county and state rules still apply.
Can I build ADUs on both parcels after an SB 9 lot split in unincorporated LA County?
Only within the two-unit cap per parcel. Each new parcel can have two primary homes, or one primary home plus one ADU or JADU. That’s already how the county applies SB 9 today, and the draft would write it into the ordinance.
Can I add ADUs to lots created under SB 1123?
Not under the draft. State law lets the county decline ADUs and JADUs on SB 1123 parcels, and the draft would prohibit them.
Does the draft reduce ADUs on a normal single-family lot?
No. The county says the amendment doesn’t reduce ADU or JADU opportunities on a single-family lot that hasn’t been split under SB 9 or SB 1123.
Does this apply in Long Beach, Lakewood or other LA County cities?
No. It applies only to unincorporated LA County. Each city sets its own rules within state law.
What’s the best path for an investor who won’t live on the property?
Usually SB 9’s two-unit development path without a lot split. It allows two primary homes plus an ADU and a JADU with no owner-occupancy affidavit, and the draft doesn’t change it.
The bottom line
LA County’s draft closes the “split it and stack ADUs on both sides” idea, and it shuts ADUs out of SB 1123 lots. It leaves the strongest investor play alone: two primary homes plus an ADU and a JADU on one unsplit lot. If you’re buying in unincorporated LA County, underwrite that path first, treat the split as an owner-occupant tool, and watch for hearing dates before the rules are final.
👉 Book a buyer ADU consult call to go through your options with Dylan
Prefer to talk now? Call Dylan Serna, ADU Realtor at 714-860-2868.
Dylan Serna | The ADU Realtor | eXp Realty | DRE #02217359
This post is general information, not legal, tax or financial advice. The LA County 2026 ADU Ordinance Amendment is a draft and may change before adoption. Rents and unit counts in the example are illustrative. Confirm eligibility for any specific parcel with LA County Planning before you buy.
