California’s accessory dwelling unit law has been rewritten so many times in the past six years that even experienced real estate attorneys sometimes give clients outdated advice. What was true in 2022 isn’t true now. What city planners told homeowners in 2023 often got overruled by a state bill signed in 2024. The cumulative effect is a legal landscape that favors homeowners more than at any point in California’s housing history — but only if they understand what actually applies.
Here’s what’s current as of 2026, written for property owners who want the law explained without the statute citations.
The foundational shift: AB 68, AB 881, and what they did
Passed in 2019, these bills forced every California city to allow at least one ADU on any single-family lot. That sounds obvious now. At the time it broke decades of local zoning control. The key provisions still in effect:
- Cities cannot require owner-occupancy as a condition of ADU permits (applies to permits issued before 2025 as well, under later clarifying legislation)
- Maximum size for ADUs cannot be restricted below 800 square feet for one-bedroom units or 1,000 square feet for two-bedroom units
- Setback requirements capped at four feet for side and rear yards
- No additional parking required for ADUs within half a mile of public transit
These haven’t changed. They’re the floor below which local ordinances cannot go.
What AB 1033 added
Signed in late 2023, effective 2024. The sleeper bill of the reform era. AB 1033 allows cities to opt into letting homeowners sell their ADU separately from the primary residence as a condo. Only a handful of cities have opted in so far — San Jose, Berkeley, and Oakland among them — but the trend is clear. Property owners in opted-in cities can now build an ADU, establish condo ownership, and sell it independently.
The practical effect: an ADU built for $290,000 that appraises at $450,000 as a standalone condo creates immediate liquidity. Owners aren’t required to sell. The option materially changes the long-term value calculation.
SB 1211 and multifamily expansion
Effective January 2025. SB 1211 expanded ADU allowances on multifamily parcels dramatically. Properties with existing multifamily structures can now build up to eight detached ADUs (previously capped at two). The bill also clarified that ADU conversions of existing non-habitable space (garages, storage, boiler rooms) on multifamily properties are allowed in addition to new construction.
For small apartment owners — duplex, triplex, fourplex — the bill effectively doubles or triples the developable unit count on properties that used to max out at the original structure.
The 2025 clean-up bills
AB 2533 and SB 1077, both signed in late 2024, closed several loopholes cities had been using to slow-walk ADU permits. Key provisions:
- Cities must approve or deny complete applications within 60 days (previously 60-90 days with workarounds)
- Pre-existing unpermitted ADUs can be legalized without bringing the primary residence up to current code
- Utility connection fees cannot exceed actual capacity cost (ending the practice of charging ADU owners full new-construction connection fees)
- HOAs cannot prohibit ADUs on single-family lots, with limited exceptions for genuine safety concerns
The legalization pathway in AB 2533 is particularly valuable for owners of older properties where a previous owner built an unpermitted garage conversion or backyard unit. Those can now be brought into compliance and rented legally, subject to current building and safety standards on the ADU itself.
What cities still control
Not everything is state-mandated. Cities retain authority over:
- Architectural design review (within limits — they can’t deny based on aesthetics alone)
- Fire safety requirements in Very High Fire Hazard Severity Zones
- Historic preservation overlays (though these have been narrowed by recent legislation)
- Short-term rental restrictions (many cities now prohibit Airbnb use of ADUs)
- Impact fees up to the statutory cap
The short-term rental restriction is worth flagging. Los Angeles, Santa Monica, San Francisco, and most coastal cities now prohibit ADUs from being rented for periods shorter than 30 days. Owners building with Airbnb income projections need to verify local rules before they break ground.
City-by-city variation that still matters
Despite statewide preemption, practical differences between cities remain significant.
Los Angeles runs relatively efficient permitting. Plan check typically 8–12 weeks. Utility tie-ins through LADWP have their own timeline challenges.
San Francisco remains the most difficult permitting environment in the state, despite state preemption. Plan check often stretches 14–20 weeks. Inspector availability is limited.
San Diego operates one of the faster processes — 6–10 weeks for straightforward builds. Their bonus ADU program offers additional density for properties within transit priority areas.
Berkeley and Oakland opted into AB 1033 condo conversion and have strong process support for it.
Smaller cities vary wildly. Some rural jurisdictions still resist applications and force applicants through HCD (Housing and Community Development) intervention to force compliance. HCD has become markedly more aggressive about this since 2024.
For owners trying to understand how all of this applies to their specific property, a detailed overview of the current ADU laws in California and how they interact with local ordinances saves substantial time and expensive legal consultation.
What to verify before starting a project
Six legal checkpoints every homeowner should hit before investing in design:
- Zoning confirmation. Single-family, duplex, or multifamily zoning changes what’s allowed
- Setback verification for your specific lot. The four-foot minimum applies, but steep slopes, easements, and utility rights-of-way can change what’s buildable
- Utility capacity check. New electrical service and sewer capacity aren’t guaranteed — early confirmation avoids expensive surprises
- Fire zone classification. Properties in Very High Fire Hazard Severity Zones face additional construction requirements
- HOA review. Even though HOAs can’t prohibit ADUs, they can impose design requirements. Understand them before committing
- Short-term rental rules. If rental income projections include Airbnb, confirm it’s legal in your city
The direction of travel
The California legislature has spent six years progressively removing barriers to ADU construction. Every session produces additional bills. The trend will continue through at least 2028 based on current housing targets, RHNA requirements, and political alignment on housing supply.
For property owners, the message is straightforward: the legal environment is the most permissive it’s ever been. The constraint is no longer “can I build this?” It’s “do I understand how to build it right?” That’s a much better problem to have.