California’s New ADU Laws and What They Mean for the South Bay
Accessory dwelling units are not trending by accident. Over the last two years, California has continued to tighten statewide rules that limit local barriers, speed up permitting, and expand what can be built on both single family and multifamily properties. Several of the most practical changes for everyday property owners took effect in 2025 and again on January 1, 2026. In a coastal city like Manhattan Beach, those changes interact with local zoning rules and the coastal development process, which means the experience here can be different from what owners see in inland cities.
At the local level, Manhattan Beach adopted Ordinance 25 0004 in 2025 to update its accessory dwelling unit regulations and to make sure the city’s rules match the state requirements that have been reshaped by multiple bills over the last several years. The city also filed the corresponding updates to the Local Coastal Program with the California Coastal Commission. Until the Coastal Commission certifies the amended Local Coastal Program, any property located inside the mapped Coastal Zone must follow state ADU law directly when applying for an ADU or a junior ADU. The city confirms this in its own public ADU guidance, which notes that coastal applications are processed under applicable state statutes until certification. This creates a two layer structure where inland projects follow the city ordinance and coastal projects follow state law as the controlling authority.
State law defines both ADUs and junior ADUs. An ADU is a secondary home on the property with its own entrance, kitchen, and bathroom. A junior ADU is a smaller unit of no more than five hundred square feet that is created entirely within the existing or proposed single family home. In 2024, the Legislature reorganized the ADU statutes into Government Code sections 66310 through 66342 and the California Department of Housing and Community Development released an updated handbook with a 2026 addendum explaining how new laws such as AB 2533, SB 1211, SB 543, and AB 1154 work together.
One of the most important state protections is the statewide exemption ADU. California requires every local government to allow at least one ADU of up to eight hundred square feet with four foot side and rear setbacks when the unit meets objective building and safety standards. Cities cannot use minimum lot size, floor area ratio, or lot coverage to deny that unit. This matters in Manhattan Beach because many lots, especially in the Tree Section and the Sand Section, already sit at or near their maximum allowable floor area ratio with the main house alone. Under today’s law, that is no longer a barrier. Even if the existing home is already at the FAR limit, the owner can still build an ADU of up to eight hundred square feet within the exemption envelope as long as the design meets objective standards.
Floor area ratio itself is a straightforward zoning calculation. It is the total interior livable square footage of all structures on the lot divided by the square footage of the lot. A five thousand square foot lot with a floor area ratio of zero point five five would typically allow two thousand seven hundred fifty square feet of livable space in the primary structures. Older thinking treated that number as an absolute ceiling. Current ADU law supersedes that idea by requiring the city to allow at least one eight hundred square foot ADU with four foot setbacks regardless of the FAR math applied to the main residence. This is one reason ADUs have become more realistic for coastal homeowners.
Junior ADUs follow a different set of rules because they must be built within the existing or proposed single family residence. They are capped at five hundred square feet and must have their own entrance and an efficiency kitchen. A junior ADU can share the bathroom with the main house or have its own. Historically, junior ADUs required the owner to live on the property. AB 1154 narrowed that rule so that owner occupancy is only required when the junior ADU shares sanitation with the main residence. If the junior ADU includes its own bathroom, owner occupancy is not required under state law. A junior ADU must also be rented for terms longer than thirty days, which keeps it aligned with ADU rental rules and outside the short term rental category.
State law also imposes specific timelines on the city. Once an ADU or junior ADU application is submitted, the city must determine whether it is complete and provide written notice within fifteen business days. Once complete, the city must approve or deny the application within sixty days and must rely only on objective standards. That sixty day decision rule has existed for several years, but SB 543 strengthened it and clarified how completeness, appeals, and interior livable space measurements apply.
These timelines now extend into the Coastal Zone. AB 462 requires a coastal development permit for an ADU to be approved or denied within sixty days when the application is complete. It also narrows the circumstances under which a coastal development permit for an ADU can be appealed to the Coastal Commission. Manhattan Beach remains in an interim phase because the Coastal Commission has not yet certified the city’s updated Local Coastal Program. During this period, coastal ADUs default directly to state law and follow the same completeness and decision timelines imposed by SB 543 and the long standing ADU statutes.
The Legislature also refined how fees apply to ADUs and junior ADUs. SB 543 prohibits development impact fees on ADUs with seven hundred fifty square feet or less of interior livable space and prohibits such fees entirely for junior ADUs of five hundred square feet or less. Larger ADUs may still be subject to impact fees, but the amount must be proportional to the size of the primary residence. In practice, this means many designers are intentionally sizing ADUs at or just below the seven hundred fifty square foot threshold because the fee savings can be meaningful in a city where construction and soft costs are already high.
For properties with older unpermitted units, AB 2533 created an updated pathway to legalization. It applies to unpermitted ADUs and junior ADUs that were constructed before January 1, 2020 and requires the city to evaluate those units under the state’s definition of a substandard building. Corrections must focus on real health and safety issues rather than forcing the entire unit to be rebuilt to current code as if it were new construction. The law also limits penalties for owners who come forward to legalize these units.
For multifamily properties, SB 1211 expanded the number of detached ADUs that can be added to a qualifying lot. Instead of the previous two unit cap, a multifamily parcel may add up to eight detached ADUs, subject to a limit tied to the number of existing primary units. SB 1211 also narrowed circumstances in which replacement parking can be required if a surface parking area is repurposed. These provisions do not change the character of Manhattan Beach multifamily neighborhoods overnight, but they do give small apartment property owners a clearer path to adding long term rental units without demolishing the existing structures.
The distinction between ADU size limits is also important. A junior ADU is always capped at five hundred square feet because it must be carved out from the space inside the existing home. A full ADU can be significantly larger. Detached ADUs can reach eight hundred, one thousand, or even twelve hundred square feet depending on the number of bedrooms and the applicable local development standards. Attached ADUs can reach up to twelve hundred square feet unless a local rule sets a lower limit that still complies with state law. None of these caps prevent a property owner from building a junior ADU inside the home and a detached ADU outside the home if the lot can support both. State law guarantees the eight hundred square foot exemption ADU regardless of how fully the main residence uses its allowable floor area.
When all of these rules are put together, the process for a Manhattan Beach homeowner becomes clearer. The first step is determining whether the property is in the Coastal Zone because that decides which review pathway applies. The next step is choosing the type of unit, whether it is an interior junior ADU, a detached ADU, an attached ADU, or a conversion of existing space. The proposed size is then compared against the seven hundred fifty and five hundred square foot fee thresholds and against the statewide exemption envelope for at least one eight hundred square foot ADU. Design standards, access, utilities, and site specifics shape the final concept. For many owners, the result is that an ADU or junior ADU is far more achievable than it would have been under the older zoning rules.
In a built out coastal city like Manhattan Beach, ADU potential affects how people approach long term ownership, multigenerational living, and rental planning. It also influences how buyers evaluate properties and how sellers position their homes in a competitive market. The state’s goal has been to reduce barriers and create predictable outcomes, and in 2026 that is exactly what the current laws are designed to do.
If you would like help understanding how these rules apply to a specific property in Manhattan Beach, feel free to reach out.
Contact us HERE or give us a call at (424) 212 3859.
Best regards,
Lindsay Woolf CA DRE 02236711
Josh Woolf CA DRE 02252408
Circa Properties CA DRE 02182130
Disclaimer: All information contained herein is compiled from sources deemed reliable, including the California Regional Multiple Listing Service (CRMLS), but is not guaranteed. Property sales, statistics, and market data are subject to change and should be independently verified. This material is provided for informational purposes only and does not constitute legal, financial, or real estate advice.
