Assembly Bill 956 (Quirk-Silva, Chapter 791 of 2026) was signed on September 29, 2026 and takes effect on January 1, 2027. It raises the number of detached ADUs a city must approve on a single-family lot from one to two, and it widens the rule that voids HOA and deed restrictions on ADUs. This page sets out what the chaptered text says and where its limits are.
Government Code section 66323 lists the ADUs a city or county must approve ministerially, without a hearing, when a homeowner applies for a building permit in a residential or mixed-use zone. Through 2026 that list includes one detached, new-construction ADU on a lot with a proposed or existing single-family dwelling. AB 956 changes one to two.
The new text reads: "Two detached, new construction, accessory dwelling units that do not exceed four-foot side and rear yard setbacks for a lot with a proposed or existing single-family dwelling."
Nothing else in that paragraph moved. A city may still limit each detached unit to 800 square feet of livable space, and may still apply the state height limits: 16 feet, or 18 feet within one-half mile walking distance of a major transit stop or high-quality transit corridor, with two more feet allowed there to match the roof pitch of the main house.
Section 66323 says a city or county must approve the listed units "or, except as provided in subdivision (b), any combination" of them. The first item on the list is unchanged: one ADU and one junior ADU created within the existing or proposed space of the house, or within an existing accessory structure, which may be expanded by up to 150 square feet for access. The second item is the one AB 956 changed: detached, new-construction ADUs, now two.
There is one trade-off, added by the bill in its own subdivision: "a local agency is not required to ministerially approve an application for a building permit to create a junior accessory dwelling unit on the same lot where two detached, new construction, accessory dwelling units have been constructed." A city may still choose to allow the junior ADU. It is no longer obliged to.
That sentence names only the junior ADU, and it speaks of a lot where two detached units "have been constructed". It does not say what happens if the junior ADU is built first. If you want all three, ask your planning department how it reads the order before you commit to a design.
For units on the by-right list, the statute bars extra local requirements: a city "shall not impose any objective development or design standard that is not authorized by this section upon any unit that meets the requirements" of the list. Lot coverage, floor-area ratio and open-space rules from the underlying zone are not on the list.
Three other rules in the same section carry over. Fire sprinklers cannot be required in the ADU if they are not required for the primary residence. A rental of a unit created under this section must be for a term longer than 30 days. And where the ADU connects to an onsite wastewater system, a city may ask for a percolation test completed within the last five years, or ten if it has been recertified.
A city or county may adopt less restrictive ADU requirements. State law sets what a city must approve, not the most it may approve, so a local ordinance can allow larger detached units or more of them.
AB 956 also amends Civil Code sections 714.3 and 4751. Those sections make void and unenforceable any covenant, deed restriction or HOA governing-document provision that "either effectively prohibits or unreasonably restricts the construction or use" of an ADU or junior ADU that meets the state requirements.
Until now they covered lots "zoned for single-family residential use". From 2027 they cover lots "zoned to allow single-family residential use", which reaches lots in zones that permit houses alongside other uses.
Reasonable restrictions are still allowed. The statute defines them as restrictions that "do not unreasonably increase the cost to construct, effectively prohibit the construction of, or extinguish the ability to otherwise construct" an ADU or junior ADU.
No. The by-right list in section 66323 applies "notwithstanding" the sections that govern local ADU ordinances, and under Government Code section 66316 a local ADU ordinance that does not meet the state requirements is void, with the city required to apply the state standards until it adopts a compliant one.
In practice, planning counters take time to update forms and handouts after January 1. If you plan to apply early in 2027, ask how the city is handling applications for a second detached unit.
AB 956 does not raise the 800 square foot figure, change setbacks or change height limits. It does not change the rules for lots with apartment buildings, which have their own items on the same list: up to eight detached ADUs on a lot with an existing multifamily dwelling, not more than the number of existing units, and two on a lot with a proposed one.
Fees are covered by a different bill. Under SB 1117, also effective January 1, 2027, impact fees on an ADU larger than 750 square feet may be charged only on the area above 750 square feet, for up to two ADUs on a lot. Two detached units of 800 square feet would each fall under that rule.
Building one unit still takes time. Across California the median from building permit to completion is 346 days, and it varies widely by city. See measured build times for 166 cities.
This page summarises the statute. It is not legal advice, and a city's reading of a new law can differ in the first months. Ask your planning or building department for its position in writing before you spend money on plans.
January 1, 2027. The Governor signed it on September 29, 2026 as Chapter 791 of the Statutes of 2026. It is an ordinary, non-urgency statute.
From January 1, 2027, a city or county must ministerially approve two detached, new-construction ADUs with four-foot side and rear setbacks on a lot with a proposed or existing single-family dwelling, if the units meet the conditions in Government Code section 66323. A city may limit each to 800 square feet of livable space and apply the state height limits.
Not as of right. AB 956 says a city is not required to approve a junior ADU on a lot where two detached, new-construction ADUs have been built under this rule. A city may still choose to allow it.
Under this by-right rule a city may limit each to 800 square feet of livable space. A city can allow larger units under its own ordinance, so check the local maximum.
Covenants and HOA provisions that effectively prohibit or unreasonably restrict an ADU that meets the state requirements are void and unenforceable under Civil Code sections 714.3 and 4751. Reasonable restrictions that do not unreasonably raise the cost or prevent construction are still allowed.