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What you can build

Del Mar ADU Regulations & Zoning

KEY RULES AT A GLANCE
Size and Separation

Maximum size: 1,000 square feet

Side/rear setbacks: 4 feet

Two story: No

Building separation: 6 feet

Additional Requirements

Soils Report: No

Building Verification Survey: Yes

Coastal permit (in some areas): Yes

Stormwater Mitigation: Yes

Number of ADUs Allowed

  • On single-family residential lots in Del Mar, you can build one ADU (either attached or detached) and one Junior ADU

  • Del Mar allows up to 2 detached ADUs for multifamily properties with an existing multi-family building (meaning the property must already have at least a duplex, not just a single-family dwelling, to build 2 ADUs).

    Effective January 2025, multifamily property owners can build as many ADUs as there are existing units, with a maximum of eight detached ADUs. This change aligns with California state law and will override any local laws that do not conform.

    Non-livable spaces within existing multi-family structures, such as storage rooms and garages, can be converted into ADUs. The maximum number of ADUs allowed in a multi-family structure is 25% of the existing units, rounded down for fractional units. A minimum of one conversion ADU is allowed.

ADU Size & Building Constraints

  • Del Mar permits detached ADUs up to 850 square feet for one-bedroom apartments and up to 1000 square feet for apartments with two or more bedrooms. The lot coverage restrictions do not apply to ADUs up to 800 square feet. This means that even if you have the maximum number of lot coverages, you can still construct an ADU this size.

  • A detached ADU can have a maximum height of 16 feet, except in the Bluff, Slope, and Canyon Overlay Zone, where the height limit is 14 feet.

    For properties located within half a mile of a major transit stop or a high-quality transit corridor, as defined in Section 21155 of the Public Resources Code, the maximum allowable height for a detached ADU is 18 feet above grade. An additional 2 feet may be permitted if the ADU’s roof pitch matches that of the primary residence.

    For an attached ADU, the maximum height is limited to 25 feet, two stories, or the base zoning requirements—whichever is lower. This only applies when the ADU is connected to the primary dwelling unit.

  • No, detached ADUs in Del Mar are not permitted to have roof decks.

  • An attached ADU can be up to 850 square feet in size, or up to 1,000 square feet if it includes more than one bedroom. Additionally, the ADU’s size cannot exceed 50% of the habitable space of the primary dwelling unit.

  • An ADU must adhere to specific objective design standards, except when these standards would prevent the construction of an 800 sq. ft. unit, as outlined in Section 30.91.040(G)(5).

    • Building Articulation: Each elevation must include at least one projection, offset, or recess of at least one foot in depth for every 20 feet to create variation in wall and roof planes.

    • Privacy Considerations: Windows and walls should be positioned to maximize privacy and minimize direct views into neighboring properties. Glass walls, defined as any wall with more than 75% glazed surface, are not allowed if visible from adjacent homes. Window placement should be staggered to avoid alignment with neighbors' windows, or should use obscured glass, clerestory windows, or higher window sills. Skylights must be tinted to reduce interior light transmission.

    • Roof Decks: Roof decks are not allowed.

    • Chimneys and Fireplaces: If included, they must be attached to the ADU and should not exceed the minimum height required by the California Building Code.

    • Roof Eaves: Eaves cannot extend into the required four-foot side or rear setbacks.

    • Architectural Consistency: If an ADU is attached to or within 20 feet of the primary dwelling, it must match the primary unit in architectural style, roof pitch, exterior materials, colors, and finishes.

Setbacks

  • ADUs must be set back at least 4 feet from the rear and side property lines, while front yard setbacks must comply with the applicable zoning regulations. If an ADU is built with the minimum 4-foot setbacks, its height cannot exceed 16 feet. Any ADU taller than 16 feet must follow the setback rules of the underlying zoning district.

    Furthermore, ADUs must adhere to the coastal bluff setback requirements in the Coastal Bluff Overlay Zone and the Beach Reservation Initiative setback in the Beach Overlay Zone. For properties located between the ocean and the first public roadway, the required street yard setback of the designated zoning must be maintained to protect public scenic views of the ocean.

  • A detached ADU must be at least six feet away from any other buildings or structures on the same lot.

Additional Requirements 

  • No, Del Mar permits digital submission of ADU applications.

  • Yes, before the framing inspection, a certification must be provided to verify that the ADU meets the required height, setback, and square footage regulations.

  • Under California Gov. Code § 65852.2, ADU regulations do not override or modify the California Coastal Act. However, the city is not required to conduct public hearings for Coastal Development Permit applications related to ADUs.

    Certain ADUs are exempt from requiring a Coastal Development Permit unless a permit is specifically required under Section 30.91.030(C)(5)(c). Exemptions include:

    1. ADUs that are fully contained within or attached to an existing single-family home.

    2. Minor modifications to an existing residential structure that do not involve replacing or removing major structural elements, such as roofs, exterior walls, or foundations, and that do not pose a risk to coastal resources under the certified Local Coastal Program (LCP).

  • No, a soils report is not generally required for ADUs in Del Mar, except for those located within the Coastal Bluff Overlay Zone.

  • Yes, Del Mar requires proper site drainage and stormwater mitigation for ADUs. This typically involves finish grading to create features like bio-swales, drainage basins, or other contouring methods to manage on-site stormwater. The cost for this work generally ranges between $5,000 and $10,000.

Parking

  • An ADU is not required to have a designated parking space if it meets any of the following conditions:

    • It is located within a half-mile walking distance of public transit, including bus stops.

    • It is within a designated historic district.

    • It is converted from an existing space within the primary residence or an accessory structure, or is attached to an existing or proposed primary dwelling.

    Starting in January 2025, if a garage, carport, covered parking structure, or uncovered parking space is demolished or repurposed to build an ADU, replacement parking will no longer be required.

  • If a parking space is required, it can be placed within the setbacks or in an existing driveway as tandem parking. Additionally, when a garage, carport, or covered parking structure is demolished or converted to create an ADU, the parking space does not need to be replaced.

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