SB 1211 Explained: Multifamily ADUs in California (2026-2027 Updates)

TL;DR

SB 1211 is a California ADU law by Senator Skinner, chaptered September 19, 2024 and effective January 1, 2025. It allows up to eight detached ADUs on a lot with an existing multifamily dwelling, capped at the number of existing units on the lot. It amended Government Code Sections 66313, 66314 and 66323.

Bill: SB 1211Effective: January 1, 2025Code: Gov. Code 66313, Gov. Code 66314, Gov. Code 66323

Last verified: October 18, 2026 against the California Legislature SB 1211 (2024) bill text and history (leginfo.legislature.ca.gov, Chapter 296, Statutes of 2024) and the recodified Government Code Section 66323(a)(4)(A), cross-checked against HCD ordinance review letters applying it in 2026.

An accessory dwelling unit, or ADU, is a second, smaller home on a lot that already has a primary dwelling. A junior ADU, or JADU, is a unit of up to 500 square feet created inside the walls of an existing house. SB 1211 is the 2024 California law that expanded how many ADUs are allowed on a lot that already has a multifamily building, and this page explains what it changed, when it took effect, and who benefits.

What does SB 1211 allow?

SB 1211 (Skinner, 2024) is Chapter 296, Statutes of 2024. It was chaptered on September 19, 2024 and took effect on January 1, 2025. SB 1211 amended Government Code Sections 66313, 66314 and 66323.

The core change is at Government Code Section 66323(a)(4): a lot with an existing multifamily dwelling may add up to eight detached ADUs, and the number allowed cannot exceed the number of existing units on the lot. The statute states, “Not more than eight detached accessory dwelling units,” and further, “the number of accessory dwelling units allowable pursuant to this clause shall not exceed the number of existing units on the lot.” For a proposed multifamily dwelling, up to two detached ADUs are allowed.

A multifamily dwelling is a building with two or more attached homes on a single lot, such as a duplex or an apartment building. A detached ADU is a standalone second home separated from the main building. A conversion ADU is an ADU created inside the existing walls of a building rather than built new.

SB 1211 multifamily ADU rules

RuleCalifornia standard under SB 1211StatuteSource
Detached ADUs on a lot with an existing multifamily dwellingUp to eight detached ADUsGov. Code 66323(a)(4)Ch. 296, Statutes of 2024
Cap on that detached countCannot exceed the number of existing units on the lotGov. Code 66323(a)(4)Ch. 296, Statutes of 2024
Detached ADUs for a proposed multifamily dwellingUp to two detached ADUsGov. Code 66323(a)(4)Ch. 296, Statutes of 2024
Conversion ADUs inside an existing multifamily buildingAt least one, up to 25 percent of existing unitsGov. Code 66323(a)(3)(B)Ch. 296, Statutes of 2024
Sections amendedGovernment Code 66313, 66314 and 66323Gov. Code 66323Ch. 296, Statutes of 2024

How many detached ADUs does SB 1211 allow on a multifamily lot?

SB 1211 allows up to eight detached ADUs on a lot that already has a multifamily dwelling, under Government Code Section 66323(a)(4). The count is capped at the number of existing units on the lot. A four unit building can add up to four detached ADUs, not eight, because the statute says the number allowed cannot exceed the number of existing units on the lot. A building with eight or more existing units reaches the ceiling of eight detached ADUs.

What are conversion ADUs inside a multifamily building?

Separate from the detached rule, Government Code Section 66323(a)(3)(B) allows conversion ADUs created within an existing multifamily building. A local agency must allow at least one such ADU, and up to 25 percent of the existing multifamily dwelling units. The statute says a city must permit “at least one accessory dwelling unit within an existing multifamily dwelling” and up to “25 percent of the existing multifamily dwelling units.” These conversion ADUs come from space such as storage rooms, boiler rooms, passageways, attics, basements or garages inside the existing structure.

Who benefits from SB 1211?

SB 1211 primarily benefits owners of apartment buildings and other multifamily properties. An owner of an existing multifamily dwelling can add detached ADUs up to the number of existing units, capped at eight, and can also convert interior space into ADUs up to 25 percent of existing units.

SB 1211 does not change the counts for a single family lot. Single family owners rely on the separate single family rules, where a lot may have at least one ADU plus one JADU under Government Code Section 66323(a)(1) and (a)(2). From January 1, 2027, AB 956 (Stats. 2026, ch. 791) raises the detached new-construction count on a single-family lot to two. For how big any of these units can be, see our California ADU size limits page.

How SB 1211 connects to other California ADU laws

SB 1211 sits alongside several other recent California ADU statutes, each covered on its own page.

  • The California ADU law tracker follows the newest bills, including the four ADU laws signed in October 2025.
  • AB 2533 addresses unpermitted ADUs.
  • The 2021 SB 9 lot split law governs splitting a single family lot rather than adding ADUs to a multifamily lot.
  • AB 1033 lets a city opt in to allowing an ADU to be sold separately as a condominium.

For the full statewide rules on size, setbacks, height, parking and fees, see the California ADU law and permits pillar. You can also browse the ADU laws library for other states.

What changed in 2026?

SB 1211 took effect on January 1, 2025, so its multifamily ADU counts were already in force before 2026. The four ADU laws California enacted in 2025 (AB 462, AB 1154, the 2025 SB 9 and SB 543) took effect for 2026 and are tracked on our California ADU law tracker. Those bills did not repeal the SB 1211 multifamily counts, which remain at Government Code Section 66323.

What changes in 2027?

SB 1211’s multifamily counts do not change in 2027. The one confirmed 2027 change sits next door: AB 956 (Stats. 2026, ch. 791), effective January 1, 2027, raises the number of detached new-construction ADUs on a single-family lot from one to two. Our California ADU law tracker covers it.

Frequently Asked Questions

What is SB 1211 in California?

SB 1211 is a 2024 California ADU law by Senator Skinner, Chapter 296, Statutes of 2024. It was chaptered on September 19, 2024 and took effect on January 1, 2025. It expands the number of ADUs allowed on a lot with an existing multifamily dwelling.

How many detached ADUs does SB 1211 allow?

SB 1211 allows up to eight detached ADUs on a lot with an existing multifamily dwelling, under Government Code Section 66323(a)(4). The number cannot exceed the number of existing units on the lot. A proposed multifamily dwelling may have up to two detached ADUs.

Does SB 1211 apply to single family homes?

No. SB 1211 expands ADU counts on lots with a multifamily dwelling. Single family lots follow the separate rules in Government Code Section 66323, which allow at least one ADU plus one JADU per lot. From January 1, 2027, AB 956 raises the detached new-construction count on a single-family lot to two.

How many conversion ADUs can go inside an existing apartment building?

Under Government Code Section 66323(a)(3)(B), a city must allow at least one ADU inside an existing multifamily building, and up to 25 percent of the existing multifamily dwelling units. These come from converting interior space in the existing structure.

When did SB 1211 take effect?

SB 1211 was chaptered on September 19, 2024 and took effect on January 1, 2025.

Sources

  1. California Legislature, SB 1211 (2024), text and history: https://leginfo.legislature.ca.gov/faces/billTextClient.xhtml?bill_id=202320240SB1211
  2. California Government Code, Section 66310 and following (ADU law, including Section 66323): https://leginfo.legislature.ca.gov/faces/codes_displayText.xhtml?division=1.&chapter=13.&lawCode=GOV&title=7.
  3. California Department of Housing and Community Development, Review of San Pablo’s ADU Ordinance (May 2026), applying SB 1211’s eight-detached-ADU rule: https://www.hcd.ca.gov/sites/default/files/docs/policy-and-research/ordinance-review-letters/san-pablo-adu-findings-052026.pdf
  4. California Legislature, AB 956 (2026), Stats. 2026, ch. 791, bill text and history: https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=202520260AB956

Disclaimer

This page is general information, not legal advice. ADU law changes often and cities apply it differently. Confirm the current rules with your local planning department before you build.

Related ADU laws

Other laws and rules in the same silo, kept in step as each one goes live.

CaliforniaNew California ADU LawsCalifornia signed ten housing bills in 2026 that matter to ADU owners, most effective January 1, 2027. AB 956 allows two detached ADUs on a single-family lot instead of one, and SB 1117 limits impact fees to the space above 750 square feet. Others cap plan check at two rounds and ease prefab rules.CaliforniaAB 1033 ExplainedAB 1033, signed October 11, 2023 and effective January 1, 2024, lets a California city opt in by local ordinance to allow an ADU to be sold separately from the main house as a condominium. As of September 25, 2026, four cities we track have opted in: San Jose, San Diego, San Francisco and Berkeley.CaliforniaAB 2533 ExplainedCalifornia's AB 2533 took effect January 1, 2025 and amended Government Code Section 66332. It bars a local agency from denying a permit to legalize an unpermitted ADU or JADU built before January 1, 2020, unless correcting a violation is necessary to fix a Health and Safety Code 17920.3 substandard condition.CaliforniaAB 956 ExplainedAB 956 (Quirk-Silva), Chapter 791, Statutes of 2026, takes effect January 1, 2027. It requires every California city to approve two detached, new-construction ADUs by right on a lot with a single-family home, up from one. A city may cap each at 800 square feet of livable space.CaliforniaHow Big Can an ADU Be in California? ADU Size Limits (2026-2027 Updates)California law requires cities to allow an ADU of at least 850 square feet for a studio or one bedroom, and 1,000 square feet for two or more bedrooms, under Government Code Section 66321. A detached ADU of up to 800 square feet is allowed by right. Interior livable space is measured under SB 543, effective January 1, 2026.CaliforniaSB 1117 ExplainedSB 1117 (Cervantes), Chapter 809, Statutes of 2026, takes effect January 1, 2027. For up to two ADUs on a lot, a California city may charge impact fees on an ADU over 750 square feet only on the interior livable space above 750, still in proportion to the main house. An 800 square foot ADU is charged on 50 square feet.