Permitting · 8 min read · April 15, 2026 · 376 words
ADU vs SB9 lot split: which path actually fits your lot
Two state laws now let LA homeowners add density. SB9 splits the lot and creates a separately sellable parcel; ADU law adds a unit. The decision turns on three numbers — and one local opt-out.
Key takeaways
- Lot size. SB9 requires the resulting parcels to be at least 1,200 sq ft each. Below 2,400 sq ft total, SB9 is off the table.
- Slope. SB9 explicitly excludes lots with average slope greater than 25%. Most LA hillside lots fail this test — see [hillside ADUs](/guides/adu-soils-hillside-la) for the geo report context.
- Hazard overlays. Very High Fire Hazard Severity Zones, [Alquist-Priolo Earthquake Fault Zones](https://www.conservation.ca.gov/cgs/alquist-priolo), and floodways are SB9-ineligible by statute.
Answered in this guide
Jump straight to the question you came in with — every answer is on this page, with links onward to the deeper guide.
- What is SB-9 and does it apply to me?
- What about hillside or coastal lots?
- I'm in an HPOZ — can I still build?
- Do you handle the permitting?
- What setbacks and height limits apply?
- How long does an ADU project take in Los Angeles?
More across the studio · the full FAQ map · the reference desk
SB9 (the California HOME Act) and ADU law solve different problems. ADU law lets you add up to two units to an existing lot. SB9 lets you split a single-family lot into two parcels and build up to two units on each. They're stackable in theory, but LA has restrictive overlays that often force a choice — and the 2025 ADU rulebook is what governs the ADU lane.
The three numbers that decide
- Lot size. SB9 requires the resulting parcels to be at least 1,200 sq ft each. Below 2,400 sq ft total, SB9 is off the table.
- Slope. SB9 explicitly excludes lots with average slope greater than 25%. Most LA hillside lots fail this test — see hillside ADUs for the geo report context.
- Hazard overlays. Very High Fire Hazard Severity Zones, Alquist-Priolo Earthquake Fault Zones, and floodways are SB9-ineligible by statute.
What SB9 actually unlocks
SB9 splits a lot 50/50 (or close to it), produces two separately sellable parcels, and allows up to two units on each parcel — for a theoretical maximum of four units. In practice, LA's enforcement of the owner-occupancy affidavit and the requirement that the splitter live on-site for three years dampens speculative use.
What ADU law unlocks
Stays as a single parcel. You can add one detached ADU plus one JADU (junior ADU) in many cases. No owner-occupancy requirement (suspended through 2025). Faster — by-right 60-day approval. Cheaper — no parcel split survey or new title insurance. The LADBS SB9 bulletin is the local interpretation.
Decision matrix
- Want to sell off the new unit separately → SB9 (with all its caveats).
- Want rental income, fastest path, lowest soft costs → ADU. The rental yield guide sizes the income side.
- Lot under 2,400 sq ft, hillside, or in a hazard overlay → ADU.
- Lot over 4,000 sq ft on a flat parcel outside hazard zones → SB9 worth modeling.
Sources
- SB9 Fact Sheet · California HCD
- California SB9 (2021) Bill Text · California Legislature
- Alquist-Priolo Earthquake Fault Zones · California Geological Survey
- LADBS Permits & Bulletins · LA Department of Building and Safety
Next chapter · 01 of 03
Permitting · 11 min read
The 2025 LA ADU permitting rulebook, decoded
If ADU is the lane, here is the full 2025 rulebook for the route most LA homeowners actually take.
What [LADBS](https://www.ladbs.org/) and California's HCD actually require in 2025 — by-right approvals, setbacks, owner-occupancy, and the rules that quietly changed this year.
FAQ · Permitting
Common questions on permitting
The questions readers send us most after this guide.
What is SB-9 and does it apply to me?
SB-9 (the California HOME Act) lets eligible single-family lots split into two parcels and/or add a duplex. We assess eligibility during the feasibility call — roughly 60% of LA single-family lots qualify on paper, fewer in practice once HPOZ, hillside, and coastal overlays are applied. SB-9 projects can stack with an ADU for up to four units on what was a single-family lot.What about hillside or coastal lots?
Hillside requires a Methane District review (where applicable) plus a haul route plan if grading exceeds 1,000 cubic yards. Coastal Zone projects (anything west of Lincoln Blvd in Venice, for example) need a Coastal Development Permit on top of standard LADBS approval. Both are workable; both add 60–90 days.I'm in an HPOZ — can I still build?
Yes, but with design review. Historic Preservation Overlay Zones require Certificate of Appropriateness from the cultural heritage commission before permits issue. We've shepherded projects through Miracle Mile, West Adams, Whitley Heights, and Spaulding Square HPOZs. Add 8–12 weeks for the COA process.Do you handle the permitting?
Yes. We file with LADBS or your local building department, manage plan check, coordinate utility upgrades, schedule inspections, and deliver final sign-off. You don't visit the counter, we do.What setbacks and height limits apply?
Statewide ADU law (AB 68/881) overrides most local restrictions: 4-foot side and rear setbacks, 16-foot height for detached one-story, 18-foot for two-story within ½ mile of transit. Front setbacks follow the underlying zone. We model your envelope at the schematic stage.How long does an ADU project take in Los Angeles?
Most detached ADUs run 9–13 months from contract to certificate of occupancy. Garage conversions are typically 4–6 months. Permitting alone is usually 60–120 days at LADBS depending on whether we use a pre-approved standard plan or a custom design that needs full plan check.
Reference desk · Permitting
More answers from the California reference desk
City-specific questions pulled from our 5,000-answer FAQ corpus — every link opens a deeper desk page.
How long does a ADU permit take in Beverly Hills?
City of Beverly Hills Community Development runs plan check 120–180 days on a complete, code-conformant submittal for a ADU. First-cycle approvals depend on three things: a stamped structural set, a Title 24 energy report bound into the package, and a site plan with verified setbacks. Most slippage comes from missing one of those three on first submittal.Why do ADU permits get rejected in Beverly Hills?
In Beverly Hills, the five most common first-cycle corrections are: (1) Title 24 energy compliance not bound to the submittal, (2) site plan setback math off by inches, (3) structural calcs not stamped by a CA-licensed engineer, (4) utility load calculations missing for the panel upgrade, and (5) drainage/grading not addressed for impervious-surface adds. Fixing all five before submittal cuts 120–180 days off the schedule.Does state ADU law override Beverly Hills rules for my ADU?
For qualifying ADU and JADU scopes, California Government Code §65852.2 and §65852.22 preempt most local discretionary review — Beverly Hills cannot impose owner-occupancy requirements (banned by AB 976), most parking minimums near transit, or stylistic design review. Local jurisdictions still control building-code application, Title 24, utility connection, and impact fee schedules. Non-ADU scopes (full additions, remodels, hillside builds) remain fully under local control.Are pre-approved standard plans available in Beverly Hills for a ADU?
Where Beverly Hills has adopted a pre-approved standard ADU plan program, using one cuts plan check by 30–60 days and removes the structural review fee. For programs that exist (LADBS, San Jose, San Diego), the trade-off is that floor-plan changes void the pre-approval. Most owners are better off using a standard plan as a starting point and accepting the layout it ships with.How long does a garage conversion permit take in Beverly Hills?
City of Beverly Hills Community Development runs plan check 120–180 days on a complete, code-conformant submittal for a garage conversion. First-cycle approvals depend on three things: a stamped structural set, a Title 24 energy report bound into the package, and a site plan with verified setbacks. Most slippage comes from missing one of those three on first submittal.Why do garage conversion permits get rejected in Beverly Hills?
In Beverly Hills, the five most common first-cycle corrections are: (1) Title 24 energy compliance not bound to the submittal, (2) site plan setback math off by inches, (3) structural calcs not stamped by a CA-licensed engineer, (4) utility load calculations missing for the panel upgrade, and (5) drainage/grading not addressed for impervious-surface adds. Fixing all five before submittal cuts 120–180 days off the schedule.Does state ADU law override Beverly Hills rules for my garage conversion?
For qualifying ADU and JADU scopes, California Government Code §65852.2 and §65852.22 preempt most local discretionary review — Beverly Hills cannot impose owner-occupancy requirements (banned by AB 976), most parking minimums near transit, or stylistic design review. Local jurisdictions still control building-code application, Title 24, utility connection, and impact fee schedules. Non-ADU scopes (full additions, remodels, hillside builds) remain fully under local control.Are pre-approved standard plans available in Beverly Hills for a garage conversion?
Where Beverly Hills has adopted a pre-approved standard ADU plan program, using one cuts plan check by 30–60 days and removes the structural review fee. For programs that exist (LADBS, San Jose, San Diego), the trade-off is that floor-plan changes void the pre-approval. Most owners are better off using a standard plan as a starting point and accepting the layout it ships with.How long does a JADU permit take in Beverly Hills?
City of Beverly Hills Community Development runs plan check 120–180 days on a complete, code-conformant submittal for a JADU. First-cycle approvals depend on three things: a stamped structural set, a Title 24 energy report bound into the package, and a site plan with verified setbacks. Most slippage comes from missing one of those three on first submittal.
Sources & further reading
- California Government Code §65852.2 — statewide ADU framework (ministerial review, 60-day clock).
- LADBS — Accessory Dwelling Unit information bulletins and current permit fee schedule.
- HCD — California Department of Housing & Community Development, ADU handbook (2024 update).
- Internal data: aggregated from real California ADU and residential construction projects, 2018–2025.
Continue your read · the editorial path
We chained these chapters in the order LA homeowners actually need them. Each one picks up where the last one left a question open.
02 / 03
Finance · 7 min
Will your ADU trigger a property tax reassessment?
Under Prop 13 and BOE Rule 463, only the new construction value is reassessed — not the entire property. A practical walkthrough of how the LA County Assessor calculates the bump.
Read chapter →03 / 03
Cost · 9 min
The anatomy of an LA ADU build, line by line
Where every dollar of a $325,000 detached 800 sq ft ADU actually goes — soft costs, hard costs, contingencies, and the line items that surprise homeowners most.
Read chapter →
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