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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 Del Mar single-family residential lots, you may build one ADU (either attached or detached) and one Junior ADU (JADUs have an owner occupancy requirement and must be converted from existing space within the primary residence).

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

    Effective Jan 2025 (SB1211): Multifamily property owners are permitted to build as many ADUs as there are existing units, with a maximum of eight detached ADUs. This change is due to California state law and will pre-empt existing local laws that are not brought into conformance.

    Non‐livable space within existing multi‐family structures may be converted into an ADU. Examples of areas that can be converted include storage rooms and garage spaces. The maximum number of ADU allowed in a multi‐family structure is equal to 25% of the number of existing multi‐family units in the structure. Fractional units are rounded down. A minimum of one conversion ADU is allowed.

ADU Size & Building Constraints

  • Del Mar allows for a detached ADU up to 850 sqft for units with 1 bedroom, and up to 1000 sqft for 2+ bedrooms. ADUs up to 800 square feet are exempt from lot coverage requirements. (Meaning: You can build an ADU of this size even if you’re maxed out on lot coverages).

  • The height of a detached ADU can be up to 16′, though an ADU proposed within the Bluff, Slope, and Canyon Overlay Zone shall be 14′ height maximum.

    On a lot that is within one-half mile walking distance of a major transit stop or a high-quality transit corridor, as defined in Section 21155 of the Public Resources Code, the
    maximum building height of a detached ADU, shall not exceed 18 feet above grade. An additional 2 feet can be added if the ADU’s roof pitch matches the primary dwelling.

    The maximum building height for an attached ADU shall not exceed 25 feet above grade, two stories, or the base zoning requirements; whichever is lower. This shall only apply where an ADU is attached to a primary dwelling unit.

    So yes, you could build a two story ADU in some situations. Read more about two story ADUs and height limits.

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

  • The square footage of the ADU shall not exceed 850 square feet in size, or 1,000 square feet maximum if the ADU has more than one bedroom. A proposed, attached ADU shall also be subject to an additional limit of a maximum size of 50 percent of the habitable space of the primary dwelling unit.

  • The ADU shall comply with the following objective design standards, unless
    the design standards prohibit construction of an 800 sq. ft. ADU, notwithstanding Section 30.91.040(G)(5):

    1. Wall and roof planes on each elevation must be varied with at least one projection, offset, or recess of the building (of at least one foot in depth) for each 20 feet.

    2. Walls and windows shall be located so that sight lines maximize privacy and avoid direct views into neighboring homes. Glass walls (any wall plane consisting of more than 75 percent opaque or transparent glazed surface) that are visible from adjacent neighboring homes shall be prohibited. Sizing and placement of windows shall be offset to stagger the window placement in relation to the adjacent neighbor’s windows; or shall utilize obscured or opaque window glass, clerestory windows, or windows with higher sills. Installation of skylights shall be tinted to avoid interior light transmission.

    3. Rooftop decks are prohibited.

    4. Where provided, fireplaces and chimneys shall be attached to the ADU and shall be no higher than the minimum height required per the California Building Code.

    5. ADU roof eaves shall not encroach into four (4) foot side or rear setback.

    6. New detached or attached accessory dwelling units shall be constructed using the same architectural style, roof pitch, exterior building materials, colors and finishes as the primary unit if the accessory dwelling unit is attached to or located within twenty (20) feet of the primary dwelling unit.

Setbacks

  • ADUs must have 4′ minimum setbacks from rear and side-yard property lines, with front yard setback per zoning standards. An ADU taking advantage of the 4′ setbacks cannot exceed a height of 16 feet. An ADU exceeding 16′ must comply with the setbacks of the underlying zoning. In all cases, ADU shall comply with the required coastal bluff setback in the Coastal Bluff Overlay Zone and the required Beach reservation

    Initiative setback in the Beach Overlay Zone. Properties located between ocean and the 1st public roadway shall comply with the street yard setback of the applicable zone where necessary to protect public scenic views to the ocean.

  • A minimum of six feet between buildings shall be maintained between a detached accessory dwelling unit and all other buildings and structures on the lot.

Additional Requirements 

  • No, Del Mar allows digital submission of applications for an ADU.

  • Yes, Del Mar requires a certification of height, setback, and square footage compliance shall be submitted prior to framing inspection.

  • California Gov. Code § 65852.2 provides that the ADU statutes do not supersede or in any way alter or lessen the effect or application of the California Coastal Act, except that the City shall not be required to hold public hearings for Coastal Development Permit applications for ADUs.

    The following are exempt from a Coastal Development Permit, except where a permit is otherwise required pursuant to Section 30.91.030(C)(5)(c):

    i. The ADU contained entirely within or attached to an existing single dwelling unit.
    ii. Minor changes to an existing residential structure that will not involve the removal or replacement of major structural components (e.g. roofs, exterior walls, or foundations) and will have no potential to adversely impact coastal resources pursuant to the certified LCP.

    Read more about ADUs in the coastal zone.

  • No, Del Mar does not mandate soils reports for ADUs, except in the Coastal Bluff Overlay Zone.

  • Yes, Del Mar requires site drainage and storm water mitigation for ADUs. Finish grading work to create a bio-swale, drainage basin or other contouring work to handle on-site storm water will cost around $5-10K in most cases. Read more about stormwater mitigation for ADUs.

Parking

  • A parking space is not required for an ADU in any of the following instances:
    o Within a one-half mile walking distance from public transit, which includes bus stops.
    o Within an established historic district.
    o Converted from the existing space of a primary residence or accessory structure, or are attached to an existing or proposed primary residence.

    Effective Jan 2025 (SB1211): When a garage, carport, covered parking structure, or uncovered parking space is demolished or converted for construction of an ADU, replacement parking will not be required.

  • If a parking space is required, it may be located within the setbacks and in an existing driveway as tandem parking. Parking spaces don’t need to be replaced when a garage, carport, or covered parking structure is demolished in conjunction with the construction of an ADU or converted to an ADU.

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