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What you can build

Carlsbad ADU Regulations & Zoning

KEY RULES AT A GLANCE
Size and Separation

Maximum size 1200 square feet

Side/rear setbacks 4 feet

Two story Yes, in some situations

Building separation 0 feet

Additional Requirements

Soils Report Yes (>750 SF)

Building Verification Survey No

Coastal permit (in some areas) Yes

Stormwater Mitigation No

Number of ADUs Allowed

  • On Carlsbad 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).

  • Carlsbad 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.

    Additionally, 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

  • Carlsbad allows for ADUs of up to 1200 sqft. 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).

  • Yes, you may build a two story ADU in Carlsbad:

    • Above a garage (must conform with the applicable height limit of the zone, but not to exceed one-story above a one-story garage)

    • On on residential lots within one‐half mile walking distance of a major transit stop (up to 20′ in height, including up to two feet allowed to accommodate the ADU roof pitch to align with the roof pitch of the primary dwelling)

    • On lots with existing multistory multifamily dwellings (up to 18′ high)

    • Attached to the primary home (up to 25′ in height or subject to limits of the applicable zone)

    In Carlsbad, building height is measured from the lower point of the existing grade or finished grade, all the way to the highest point of the structure. See code section 21.04.065 Building Height for more detail.

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

  • The square footage of any attached ADU may not to exceed 50% of the primary dwelling square footage, or 1,200 sqft, whichever is less, but not less than 800 square feet. ADUs are also required to be 16′ or less in height, attached or detached.

  • In Carlsbad, the accessory dwelling unit shall be architecturally compatible with the main dwelling unit, in terms of appearance, materials and finished quality.

    All information verified by a Carlsbad Associate Planner in March 2022.

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 four-foot setback provision shall not be allowed to exceed a height of 16 feet. An attached or detached ADU exceeding 16 feet must comply with the setbacks of the zoning district in which it is located.

    Note that California state ADU law allow for at least an 800 sqft ADU, regardless of front setbacks and FAR. In non-coastal properties in Carlsbad, this means you could build an ADU encroaching in the front setback.

    However, for coastal properties, Carlsbad confirmed in June 2024 that they had “been told by Housing and Community Development (HCD) that for properties subject to the LCP, section 21.10.030 of the CMC will hold precedence over the current State ADU legislation. For projects located in the coastal zone, we must follow the municipal code language, and the front yard setback for ADUs would still apply.” In other words, you can’t build an ADU in the front setback in the coastal zone of Carlsbad.

  • Carlsbad currently has no minimum requirement for separation between buildings used for human habitation. Note though that additional fire code requirements will apply when <10′ of separation.

    Verified by a Carlsbad planner via email in May 2024, Section 21.10.080 of the CMC lists the development standards for detached accessory structures containing habitable space. Ordinance No. CS-432 removed the requirement that buildings used for human habitation must be at least 10 feet away from other buildings used for human habitation.

Additional Requirements

  • No, Carlsbad only requires Building Verification Surveys when the ADU is within 1′ of a setback.

  • Yes, Carlsbad requires in-person submission of plans and does not accept digital applications at this time.

  • Yes, Carlsbad requires soils reports for builds >750SF. Builds 500-749SF must include 24” footings and a 5” slab to waive a soils report (<500 SF are exempt entirely).

  • Yes, accessory dwelling units developed within the coastal zone are subject to the permit requirements of Chapter 21.201 (Coastal Development Permit).

    Read more about ADUs in the coastal zone.

Additional Requirements

  • No, Carlsbad only requires Building Verification Surveys when the ADU is within 1′ of a setback.

  • Yes, Carlsbad requires in-person submission of plans and does not accept digital applications at this time.

  • Yes, Carlsbad requires soils reports for builds >750SF. Builds 500-749SF must include 24” footings and a 5” slab to waive a soils report (<500 SF are exempt entirely).

  • Yes, accessory dwelling units developed within the coastal zone are subject to the permit requirements of Chapter 21.201 (Coastal Development Permit).

    Read more about ADUs in the coastal zone.

Multifamily

  • Up to two detached accessory dwelling units shall be permitted on a lot with an existing multifamily dwelling, not to exceed 18′ in height, and four-foot side and rear yard setbacks are maintained. A separate application is required for every JADU and ADU.

  • No, you cannot stack ADUs on top of each other in Coronado. The height limit for multifamily is 16′.

  • No, you cannot attach two ADUs to each other in Coronado.

  • Yes, existing non-livable space may be converted to ADUs (e.g. storage areas and garages). The minimum number of ADU conversions allowed is one, up to a maximum equal to 25% of the number of existing multifamily units. This is in addition to the allowed number of detached ADUs.

Parking

  • The City’s Certified Local Coastal Program (LCP), approved in 1983, mandates certain parking requirements to be met, including the number of off-street parking spaces for dwellings, to ensure and maintain public access to the coast. The California Coastal Act of 1976 is neither superseded nor in any way altered or lessened as provided for in Government Code Section 65852.2(I).

    To ensure compliance with the California Coastal Act of 1976 and the approved LCP, a maximum of one (1) parking space shall be required for each accessory dwelling unit. No additional parking is required for a JADU.

    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 side and rear setbacks and in an existing driveway as tandem parking. ADU parking within the front yard setback area is limited to within an existing driveway. If an ADU or JADU replaces an existing garage or other required parking, replacement spaces shall be provided.

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