Updated October 2026
The 2024 ADU laws are in force, and 2025 and 2026 added more. Here is what each one does, in plain terms, and what it means for your lot.
The short version
- A single-family lot can have one converted ADU, one JADU and one detached ADU under state law.
- Detached ADUs can be up to 1,200 sf. Cities must allow at least an 800 sf unit with 4 ft side and rear setbacks.
- Height: 16 ft for a detached ADU, 18 ft near qualifying transit (plus 2 ft to match the roof pitch), up to 25 ft for an attached ADU.
- No impact fees on ADUs of 750 sf or less. No owner-occupancy requirement for ADUs.
- The city must approve or deny a complete application within 60 days.
Laws in effect since January 1, 2024
- AB 976: permanently bars cities from requiring owner occupancy for ADUs.
- AB 1033: lets cities opt in to allow ADUs to be sold separately as condominiums. It only applies where a city has adopted an ordinance.
- AB 1332: required every city to run a pre-approved ADU plan program by January 1, 2025.
Laws in effect since January 1, 2025
- SB 1211: on multifamily lots, allows up to 8 detached ADUs, capped at the number of existing units, and bars replacement parking when uncovered spaces are removed for an ADU.
- AB 2533: extends the path to legalize unpermitted ADUs to units built before January 1, 2020.
Laws in effect since January 1, 2026
- SB 543: 15-business-day completeness check, size limits measured as interior livable space, and no impact fees on JADUs of 500 sf or less.
- AB 1154: owner occupancy applies only to a JADU that shares a bathroom with the house. JADUs, and most ADUs, can’t be rented for under 30 days.
The older laws still stand: AB 2221 and SB 897 (2023) set the height rules and stop front setbacks from blocking an 800 sf unit. The ADU sections of the Government Code were renumbered in 2024 (SB 477) and now sit at sections 66310–66342.
How we use it
We read the ADU rules as one tool among several. At the Foothill Residence, a 2-bed unit with a garage sits under the main home. At Mariposa Complex in Altadena, SB 1123 (not an ADU law) let us place three homes on one lot, each with an attached ADU. See our small-lot subdivision page for that path.
A home and a second household, stacked on one lot.
Have a lot in mind?
Send us the address and we’ll tell you what it can hold. Book a free consultation → · Follow @ydsarch on Instagram
