Carlsbad ADU Regulations & Zoning

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)

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.

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.

For units larger than 800sqft, the minimum required distance between structures is 10′ (Meaning: the ADU must be this far from the primary home or any other existing structures). Per an assistant planner at the City of Carlsbad in September 2022, for units less than 800 sqft, no separation distance applies (though additional fire code requirements will apply <6′ of separation).

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

Yes, Carlsbad requires a soils report for ADUs of 500sqft or more.

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.

In areas within 1/2 mile of public transit, you may be able to stack detached ADUs on top of each other in Carlsbad, as the maximum height allowed in this scenario is 20′. You are also allowed to stack attached ADUs.

We have received different viewpoints on this topic. We are designing & building two stacked ADUs that are attached to the main home.

Yet, per the city of Carlsbad as of Nov 2021, the city has interpreted that multi-family lots are permitted two freestanding, detached accessory dwelling units which are detached from the multi-family residence as well as from one another.

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.

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.