Gov. Code § 66321

Unit size limitsTITLE 7. PLANNING AND LAND USE › DIVISION 1. PLANNING AND ZONING › CHAPTER 13. Accessory Dwelling Units › ARTICLE 2. Accessory Dwelling Unit Approvals

Key provisions · Claude summary, not statute text

Allows local minimum and maximum ADU size requirements but sets floors on size, development standards, and height that local rules may not go below.

Unit size. Local agencies may set minimum and maximum unit sizes for attached and detached ADUs, but a minimum may not prohibit an efficiency unit, and a maximum may not be less than 850 sq. ft. of interior livable space, or 1,000 sq. ft. for an ADU with more than one bedroom. (a), (b)(1)–(2)
800-square-foot floor. No zoning clearance or separate zoning review, size limit, percentage-of-primary-dwelling limit, or limit on lot coverage, FAR, open space, front setbacks, or minimum lot size may prevent an ADU of at least 800 sq. ft. with four-foot side and rear setbacks that complies with other local standards. (b)(3)
Height. Height limits must allow at least 16 feet for a detached ADU; 18 feet for a detached ADU within one-half mile walking distance of a major transit stop or high-quality transit corridor (plus two feet for a roof pitch aligned with the primary dwelling); 18 feet for a detached ADU on a lot with a multifamily, multistory dwelling; and 25 feet or the primary dwelling's height limit, whichever is lower, for an attached ADU, which need not exceed two stories. (b)(4)

Paraphrased from the statute text; each point cites its subdivision. Check the text before relying on it.

§ 663212 subdivisions

(a)Minimum and maximum unit sizes

Subject to subdivision (b), a local agency may establish minimum and maximum unit size requirements for both attached and detached accessory dwelling units.

(b)Prohibited size and height standards4 paragraphs

Notwithstanding subdivision (a), a local agency shall not establish by ordinance any of the following:

(1)No minimum size prohibiting efficiency units

A minimum square footage requirement for either an attached or detached accessory dwelling unit that prohibits an efficiency unit.

(2)Maximum size limits set too low2 subparagraphs

A maximum square footage requirement for either an attached or detached accessory dwelling unit that is less than either of the following:

(3)No standards precluding 800 square foot ADU

Any requirement for a zoning clearance or separate zoning review or any other minimum or maximum size for an accessory dwelling unit, size based upon a percentage of the proposed or existing primary dwelling, or limits on lot coverage, floor area ratio, open space, front setbacks, and minimum lot size, for either attached or detached dwellings that does not permit an accessory dwelling unit with at least 800 square feet of interior livable space and with four-foot side and rear yard setbacks to be constructed in compliance with all other local development standards.

(4)Minimum height allowances4 subparagraphs

Any height limitation that does not allow at least the following, as applicable:

Source. California Code text from the Legislature's bulk download (the same data as leginfo), reproduced character for character (spacing normalized). Current page on leginfo ↗

History. (Amended by Stats. 2025, Ch. 520, Sec. 5. (SB 543) Effective January 1, 2026.)

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