California ADU rules & zoning (2026)

By Jarrod·Editor·Last verified October 2026

California state law preempts most local ADU restrictions. These are the universal rules every California city must allow. Your city may be more permissive on some — never more restrictive.

The state-law floor (every California city must allow)

Rule	Standard
ADUs allowed on single-family lot	Yes — required by state law
Max units per lot	Single-family lot: 1 ADU converted from existing space, 1 JADU and 1 detached new ADU. From Jan 1, 2027 a second detached ADU, though a city need not then also approve a JADU. Lot with an existing multifamily building: up to 8 detached ADUs, not more than its existing units, plus conversions of non-livable space
Owner-occupancy required	Cities can't require for ADUs (state preempts)
Min side & rear setback (detached)	4 feet
Max height (detached, single-family lot)	16 ft; 18 ft within one-half mile walking distance of a major transit stop or high-quality transit corridor
Off-street parking	None may be required within one-half mile walking distance of public transit, and in several other cases; elsewhere at most one space per ADU or per bedroom, whichever is less. Parking removed to build an ADU never has to be replaced
Max ADU size (detached)	850 sqft for studio/1BR; 1,000 sqft for 2+BR (city may allow more)
Min lot size	A city may not impose a minimum lot size requirement for ADUs
Permit timeline (ministerial)	60 days from complete application (state law)
Fire sprinklers required in ADU	Not required if they are not required for the primary residence; ADU construction cannot trigger sprinklers in the existing primary dwelling
Impact fees	None on ADUs with 750 sqft or less of interior livable space. Any impact fees charged on larger ADUs must be proportional to the primary dwelling; from Jan 1, 2027, for up to two ADUs on a lot, they may be charged only on the area above 750 sqft

The state laws that built this floor

Listed by the year signed. Each of these was a majority-vote bill and took effect on the following January 1.

SB 1069 and AB 2299 (2016) — required ministerial approval of ADUs, with no discretionary review, and barred parking requirements near public transit.
SB 13, AB 68 and AB 881 (2019) — set the 60-day approval deadline, capped side and rear setbacks at four feet, protected an 800 sqft ADU from local size and lot-coverage rules, barred impact fees on ADUs under 750 sqft, allowed a JADU alongside an ADU, and barred owner-occupancy requirements until 2025.
AB 2221 and SB 897 (2022) — required written reasons with any denial, stopped front setbacks from blocking an 800 sqft ADU, required local standards to be objective, and raised the heights cities must allow to 18 feet near a major transit stop or high-quality transit corridor and up to 25 feet for attached ADUs.
AB 976 (2023) — made the ban on owner-occupancy requirements for ADUs permanent. The earlier ban was due to lapse in 2025.
AB 1033 (2023) — lets a city adopt an ordinance allowing an ADU to be sold separately from the main house as a condominium. It applies only where the city has opted in.
SB 1211 (2024) — raised the limit on detached ADUs on a lot with an existing multifamily building from two to as many as eight, not more than the building's existing units.
AB 1154 (2025) — limited the JADU owner-occupancy requirement to JADUs that share sanitation facilities with the existing structure.

Changing on January 1, 2027

Seven bills signed in September 2026 take effect on January 1, 2027. The three that change the table above:

AB 956 — cities must approve two detached, new-construction ADUs on a lot with a single-family home, up from one. A city need not also approve a JADU where two detached ADUs have been built this way.
SB 1117 — on an ADU larger than 750 sqft, impact fees apply only to the area above 750 sqft, for the first two ADUs on a lot.
AB 1621 — no more than two plan-check rounds on a building permit application.

All seven 2027 laws, checked against the bill text →

Where cities can still set their own rules

State law sets a floor, not a ceiling. Cities retain authority over:

Design standards — exterior materials, roof pitch, façade treatments (must be objective, not subjective)
Maximum size beyond the state floor — many cities allow 1,200 sqft+ detached ADUs
Front setbacks, as long as they still leave room for an ADU of at least 800 sqft (state law caps side and rear setbacks at four feet)
Tree protection — many cities require arborist review
Hillside design review — for sloped sites in hillside zones
Historic district review — for ADUs in heritage-listed neighbourhoods
Permit and plan-check fees, if charged consistently with the applicable state fee statutes

California ADU rules & zoning (2026)

The state-law floor (every California city must allow)

The state laws that built this floor

Changing on January 1, 2027

Where cities can still set their own rules

Find your city's specific rules