Lake Forest, CA Accessory Structures: ADU Rules (2026)

The City of Lake Forest adopted its own ADU and Junior ADU ordinance (Ordinance No. 336, July 2020), codified at Municipal Code Section 9.146.050, to implement state ADU law (Gov. Code 65852.2 / 66310 et seq.). ADU and JADU applications are processed ministerially without a public hearing, and the City must approve or deny a complete application within 60 days. Per Section 9.146.050(G)(1)(a), a Class 2 ADU may be up to 850 square feet for a studio or one-bedroom unit and 1,000 square feet for a unit with two or more bedrooms. JADUs are limited to 500 square feet of interior livable space and must be created within the walls of an existing or proposed single-family home (Section 9.146.050(C)(6)(a)). Detached ADUs may not exceed 16 feet, or 18 feet within one-half mile of major transit; attached ADUs may reach 25 feet or the underlying zone limit, whichever is lower (Section 9.146.050(F)(2)). New-construction ADUs must observe four-foot side and rear setbacks (Section 9.146.050(G)(2)). One off-street parking space is generally required per ADU or per bedroom, whichever is less, with exemptions for units within one-half mile of transit. A 2022 California HCD review found several local provisions more restrictive than state law, including a two-bedroom cap and an efficiency-kitchen size limit, which the state directed the City to revise.