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California Court of Appeal Holds Most Attached ADU Projects Are Not Subject to CDP Requirements under the Coastal Act or City’s Local Coastal Program

California Court of Appeal Holds Most Attached ADU Projects Are Not Subject to CDP Requirements under the Coastal Act or City’s Local Coastal Program
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By Sergio Rudin

The case deals with the interplay between state accessory dwelling unit (ADU) requirements under Government Code section 65852.2 and the state Coastal Act. The plaintiffs applied to the City of Malibu (City) to build a new 414 square foot ADU, attached to the existing residence, and addition to the existing residence for a new primary bathroom. The City’s planning commission denied the permit application, finding that the project required a coastal development permit (CDP) under the Coastal Act (Public Resources Code section 30000 et seq.) and refused to approve a CDP as the project on the basis that the project violated the setback requirements, impervious lot coverage, and maximum allowed development footage in the City’s adopted Local Coastal Plan. [Riddick, et al. v. City of Malibu, et al., ___Cal.5th___, Case No. No. B323731 (2nd Dist. Feb. 1, 2024, as modified Feb. 22, 2024).]


Public Resources Code section 30610 of the Coastal Act includes an exemption from the CDP requirement for all “improvements to existing single-family residences,” except those developments that may have adverse environmental effect as determined by Coastal Commission regulation. Section 13250 of Title 14 of the California Code of Regulations implements this portion of the Coastal Act by requiring a CDP for projects on different kinds of environmentally sensitive sites, such as beaches and wetlands. The regulation also defines “improvements to existing single-family residences” to include all fixtures and structures directly attached to the residence, as well as a structures on the property normally associated with a single-family residence but excluding guest houses and self-contained residential units.

The City’s adopted Local Coastal Program, as certified by the Coastal Commission, includes an exemption from CDP requirements for improvements to existing single-family residences that appears based on Section 13250 of Title 14 of the California Code of Regulations. The City’s Local Coastal Program stated exemption from improvements to existing single-family residences:

. . .includes all fixtures and structures directly attached to the residence and those structures normally associated with a single-family residence, such as garages, swimming pools, fences, storage sheds and landscaping but specifically not including guest houses or accessory self-contained residential units.

The City’s language is nearly identical to the Coastal Commission’s regulation.

At the Trial Court

Plaintiffs sued seeking a writ of administrative mandate under Code of Civil Procedure section 1094.5, traditional writ of mandate under Code of Civil Procedure section 1085, and declaratory relief, and further alleged violation of the Housing Accountability Act (Government Code section 65589.5). The City argued that because Government Code section 65852.2 included language that it did not “alter or lessen” requirements under the Coastal Act, the City did not have a ministerial duty to process the plaintiffs’ permit application and traditional mandate was not appropriate. The City also argued it was entitled to deference in the interpretation of its own exemptions under its adopted Local Coastal Program. The trial court issued an order granting the traditional writ of mandate and directing the City to process the permit as exempt from CDP requirements but denied all other causes of action. Notably, the trial court also refused to grant deference to the Coastal Commission in its interpretations of the exemption in Public Resources Code 30610 or to the City in its analogous exemption in the Local Coastal Program, noting that neither agency had long-standing opinions on how the exemptions should be interpreted.

The Court of Appeal’s Decision

On appeal, the City argued that the trial court misinterpreted the CDP requirements under the Coastal Commission’s regulation as well as the City’s Local Coastal Program, and that neither attached nor detached ADUs were exempt from CDP requirements. Plaintiffs cross-appealed and argued that their attached ADU should be exempt as an “improvement to an existing single-family residence, and that they had a right under the state ADU law to a permit, the trial court should have directed the issuance of the permit under their request for a traditional writ of mandate. The Court of Appeal upheld the trial court order in its entirety.

The Court of Appeal indicated that the issue of interpreting the City’s Local Coastal Program was subject to de novoreview, and that the City was not entitled to any deference with respect to the language of its Local Coastal Program.

The court found that he the meaning of the exemption was sufficiently clear from the plain language and required that the City process the ADU project without requiring a CDP permit. The court noted that the language of the City’s exemption was modeled on the Coastal Commission’s regulation, and both used “directly attached” in referring to exempt improvements but excepted from permitting “self-contained residential units” which were not “directly attached” but still on the property.

Accordingly, the court found the plain language of the exemption supported a conclusion that detached guest houses and self-contained residential units required a CDP, but that attached ADU projects did not. The court also noted that this reading was consistent with the Coastal Commission’s regulation, and it rejected the City’s position that it intended a different meaning, stating it did not believe that the City “harbored an unexpressed intent to alter materially the meaning and effect of the [Coastal Commission]r egulation upon which it is based.” The court also rejected a number of arguments by the City that this would create inconsistencies with other provisions of the City’s Local Coastal Program.

The court also rejected plaintiffs’ arguments that they were entitled to an order granting their ADU application, finding that the issues raised by plaintiffs related to enforcement of the judgment and were not properly before the court.

Conclusion and Implications

In addition to clarifying permit requirements under Malibu’s Local Coastal Program, the decision clarifies permit requirements for ADU projects under the Coastal Act. Since most attached ADU projects will not be subject to permitting under the Coastal Act as long as they are not located in specified environmentally sensitive areas, the decision will likely result in more attached ADU projects in coastal zones, as compared to detached ADU projects which may face more regulatory hurdles. A copy of the decision may be found here: