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HomeGovernment CodeDiv. 1Ch. 13Art. 2§ 66321 Accessory Dwelling Unit Size Limits

§ 66321 Accessory Dwelling Unit Size Limits

Government Code·California
AI Summary·Official Text·Key Terms·Related Statutes·References
AI SummaryVerified

§ 66321 Accessory Dwelling Unit Size Limits

Key Takeaways

  • •Local governments can set size rules for small homes (accessory dwelling units) in backyards.
  • •They can't make the smallest size too big—tiny homes (efficiency units) must be allowed.
  • •They can't make the biggest size too small—at least 850 sq ft (or 1,000 sq ft for 2+ bedrooms).
  • •Height rules must allow at least 16 ft for detached small homes (or 18 ft near transit or for multifamily lots).

Example

You want to build a small home in your backyard for your parents to live in.

The city can't stop you from building it just because it's small (like 500 sq ft) or tall (like 16 ft). They also can't say it has to be smaller than 850 sq ft if it's just one bedroom.

AI-generated — May contain errors. Not legal advice. Always verify source.

Official Source
View on CA.gov

§ 66321 Accessory Dwelling Unit Size Limits

(a) Subject to subdivision (b), a local agency may establish minimum and maximum unit size requirements for both attached and detached accessory dwelling units. (b) Notwithstanding subdivision (a), a local agency shall not establish by ordinance any of the following: (1) A minimum square footage requirement for either an attached or detached accessory dwelling unit that prohibits an efficiency unit. (2) A maximum square footage requirement for either an attached or detached accessory dwelling unit that is less than either of the following: (A) Eight hundred fifty square feet. (B) One thousand square feet for an accessory dwelling unit that provides more than one bedroom. (3) 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 at least an 800 square foot accessory dwelling unit with four-foot side and rear yard setbacks to be constructed in compliance with all other local development standards. (4) Any height limitation that does not allow at least the following, as applicable: (A) A height of 16 feet for a detached accessory dwelling unit on a lot with an existing or proposed single family or multifamily dwelling unit. (B) A height of 18 feet for a detached accessory dwelling unit on a lot with an existing or proposed single family or multifamily dwelling unit that is within one-half of one mile walking distance of a major transit stop or a high-quality transit corridor, as those terms are defined in Section 21155 of the Public Resources Code. A local agency shall also allow an additional two feet in height to accommodate a roof pitch on the accessory dwelling unit that is aligned with the roof pitch of the primary dwelling unit. (C) A height of 18 feet for a detached accessory dwelling unit on a lot with an existing or proposed multifamily, multistory dwelling. (D) A height of 25 feet or the height limitation in the local zoning ordinance that applies to the primary dwelling, whichever is lower, for an accessory dwelling unit that is attached to a primary dwelling. This subparagraph shall not require a local agency to allow an accessory dwelling unit to exceed two stories. (Added by Stats. 2024, Ch. 7, Sec. 20. (SB 477) Effective March 25, 2024.)

Last verified: January 22, 2026

Key Terms

complianceordinancefinecoveragerequirementpublic resources codeclearancedevelopment

Related Statutes

  • § 66326 Local Housing Ordinance Compliance
  • § 51115.1 Timber Operations Zoning Presumption
  • § 65852.21 Two-Unit Housing Approval
  • § 39587 Alternative Local Hearing Process
  • § 5951 Local Agency Security Sales

References

  • Official text at leginfo.legislature.ca.gov
  • California Legislature. Government Code. Section 66321.
View Official Source