California ADU Law Has Changed More Than Most Homeowners Realize
Since 2017, California has passed over a dozen bills specifically targeting ADU production. The cumulative effect has been a dramatic simplification of the permitting process — but the specific rules are still complex enough that many homeowners (and some contractors) get them wrong. Here's the current state of the law as of early 2026.
Max ADU size: 1,200 sq ft (detached) or 50% of primary dwelling, whichever is less
Max JADU size: 500 sq ft
Min setbacks (detached ADU): 4 ft from rear and side property lines
Owner-occupancy requirement: None through January 1, 2025 (now expired — see below)
Permit review timeline: 60 days for complete applications
Impact fees: Waived for ADUs under 750 sq ft
The Bills That Matter Most in 2026
AB 68 and AB 881 — The Foundation
These 2019 and 2020 bills established most of the current ADU framework: eliminated most local restrictions on ADU size and setbacks, prohibited minimum lot size requirements, and mandated that cities approve ADUs ministerially (no discretionary hearings, no neighborhood votes). If a project complies with the code, it must be approved.
SB 9 — Second Units on Single-Family Lots
Effective January 2022, SB 9 allows homeowners to split a single-family lot into two parcels and build two units on each — creating potential for up to four units on what was previously a single-family property. This is distinct from the ADU program but can be combined with it in some configurations. Local jurisdictions are still working through implementation, and not all lots qualify (historic districts, fire hazard zones, and certain flood zones have exceptions).
Owner-Occupancy: The Rule That Lapsed
California temporarily eliminated the owner-occupancy requirement for ADUs from 2020 through January 1, 2025. That exemption has now expired. Under current law, if you have a JADU, you are required to occupy either the primary residence or the JADU. For full ADUs, the requirement depends on your local jurisdiction — many cities chose not to reinstate it, but you should verify with your city before assuming you can rent both units simultaneously.
AB 2533 (2024) — Streamlined ADU Approval
Signed in September 2024 and effective January 2025, AB 2533 further tightened approval timelines, eliminated several remaining local restrictions, and clarified that permit applications must receive a written response within 60 days. If a city fails to act within 60 days on a complete application, the permit is deemed approved by operation of law.
Setbacks: The Most Commonly Misunderstood Rule
State law requires a minimum 4-foot setback from the rear and side property lines for a detached ADU. This supersedes any stricter local ordinance. However, there are nuances:
- Existing structures: A detached structure being converted to an ADU can remain in its current location regardless of setbacks, as long as it won't be expanded beyond the existing footprint.
- Front setback: State law doesn't set a minimum front setback for ADUs, but your city's front yard setback ordinance typically still applies.
- Fire separation: Even with 4-foot side setbacks, you'll need to meet fire separation requirements from the property line — typically requiring 1-hour fire-rated construction on walls within 5 feet of the property line.
Utility Connections and Fees
State law prohibits cities from requiring a new or separate utility connection for an ADU that is attached to the primary residence. For detached ADUs, cities can require a new connection — but the connection fee must be proportionate to the ADU's impact, not a full new-service charge.
Impact fees are waived entirely for ADUs under 750 sq ft. For ADUs 750 sq ft and over, fees are charged proportionately based on square footage relative to the primary dwelling.
Rent Control Does Not Apply to New ADUs
ADUs built after February 1, 1995 are exempt from the Costa-Hawkins Rental Housing Act restrictions and local rent control ordinances. You can charge market rate and raise rent to market at turnover. This is one of the most significant financial benefits of new ADU construction versus buying an existing rental property.
Practical Takeaways for 2026
For most homeowners on a standard single-family lot in Los Angeles, the current law means: you can build a detached ADU up to 1,200 sq ft with 4-foot setbacks, the city must respond to your permit application within 60 days, impact fees are waived if you stay under 750 sq ft, and you're free from rent control on the new unit. That's a remarkably clear path to a legal, income-producing dwelling unit on your existing lot.