California ADU Laws: 2025-2026 Updates

California has been rewriting ADU law almost every year since 2017. Each legislative session brings new bills, most of which expand homeowner rights to build. Keeping up with the changes can feel like a part-time job.

Here is a summary of where things stand heading into 2026.

The Foundation: What the Big 2020 Bills Did

Before going into recent updates, a quick recap of the foundational changes that still govern most ADU decisions:

AB 68 and AB 881 (2020): Established the 4-foot minimum rear and side setback for new detached ADUs. Eliminated owner-occupancy requirements for standard ADUs. Required cities to allow at least two ADUs per lot (one standard, one JADU) on single-family properties.

SB 9 (2022): Allowed lot splits on single-family lots and up to two units on each resulting lot, effectively allowing up to four units on most single-family properties in California when combined with ADU rights.

These bills are the reason so many lots that were previously restricted can now build. They're in effect and not being rolled back.

2024-2025 Changes That Affect Current Projects

SB 1211 (2024): Increased the number of ADUs allowed on multifamily lots. Properties with an existing multifamily structure can now add ADUs equal to 25% of the existing unit count (up from the prior limit). This primarily affects investors and owners of small apartment buildings rather than single-family homeowners.

AB 2533 (2024): Clarified and expanded the "existing nonconforming structure" exemption. If you have a structure on your property that was legally built but doesn't meet current setback or coverage requirements, it's easier to convert it to an ADU without triggering a full zoning upgrade.

AB 1865 (2024): Required cities to process ADU applications more transparently, with clearer documentation of what was approved or denied and why. Aimed at reducing the pattern of some cities using vague or inconsistent objections to slow projects down.

What's Being Discussed for 2026

Several bills in the 2025-2026 legislative session touch ADUs. As of early 2026:

Expanded height limits: Some proposals would require cities to allow detached ADUs up to 20 feet tall in more zones, particularly near transit. Current law allows cities to cap height at 16 feet in many cases.

ADU amnesty programs: Proposals to create statewide pathways to legalize existing unpermitted ADUs, building on the programs that cities like Los Angeles and San Jose have already run locally.

Owner-occupancy reinstated for some programs: Some housing advocacy bills include nuanced owner-occupancy provisions tied to specific programs or funding, not a broad return to the old rules.

Nothing in the current legislative pipeline rolls back the core ADU rights established in 2020. The direction continues to be more permissive.

What Still Varies By City

Despite the state's increasing standardization, several things still differ meaningfully by city:

Permit fees: Cities set their own fee schedules. The gap between a $6,000 permit in Sacramento and a $22,000 permit in Los Angeles is real, and it affects project economics.

Setbacks beyond the 4-foot minimum: Some cities still have slightly different setback rules in specific zones or for specific ADU types. Check your city's current ordinance, not just the state minimum.

Design standards: Some cities require ADUs to match the architectural style or materials of the primary home. This adds cost and can limit prefab options.

Local rent control: State law exempts most new ADUs from rent control, but local ordinances vary in their construction date cutoffs. Know your city's rules before assuming your ADU is exempt.

Pre-approved plan programs: These vary enormously. LA and San Jose have robust libraries. Other cities have nothing. If your city has pre-approved plans, use them. The permit process is faster and cheaper.

Practical Takeaways

For homeowners planning to build in 2026, the most important things to know:

• ›The core rights granted in 2020 are not being reversed. You can build with confidence.
• ›A 4-foot rear and side setback for new detached ADUs is the statewide minimum. Your city cannot require more.
• ›Garage and accessory structure conversions are allowed regardless of existing setbacks if you're not expanding the footprint.
• ›Permit fees and timelines vary by city. The regulatory environment is mostly permissive. The practical bottleneck is usually the permit process itself.
• ›If your city has pre-approved plans, check them first. You'll save time and often money.

Check your specific city's regulations on this site, and always verify current rules with the local planning department before making final decisions. The laws have been changing often enough that any guide, including this one, may miss a recent update.