What you can build

Carlsbad ADU Regulations & Zoning


Size and Separation

Maximum size 1200 square feet

Side/rear setbacks 4 feet

Two story Yes, in some situations

Building separation 10 feet, or 0 feet <800 sqft

Additional Requirements

Soils Report Yes

Building Verification Survey No

Coastal permit (in some areas) Yes

Stormwater Mitigation No

Number of ADUs Allowed

How many ADUs can you build in Carlsbad?

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).

How many ADUs does Carlsbad allow for multifamily properties?

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.

ADU Size & Building Constraints

What size detached ADU can you build in Carlsbad?

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).

Can you build a 2-story ADU in Carlsbad?

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.

Does Carlsbad allow roof decks on ADUs?

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

How big can an attached ADU be 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.

What are the requirements of the exterior of the ADU?

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.


What is the setback requirement for an ADU in Carlsbad?

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.

What is the minimum distance the ADU must be from existing structures?

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).

Additional Requirements

Does Carlsbad require Building Verification Surveys for an ADU?

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

Does Carlsbad require in-person submission of plans for an ADU?

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

Does Carlsbad require a soils report for an ADU?

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

Does Carlsbad require coastal development permits?

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.


How many ADUs does Carlsbad allow for multifamily properties?

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)

Can you stack detached ADUs on top of each other?

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.

Can you attach two ADUs to each other?

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.

Can you convert existing space to an ADU?

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.


What is the parking requirement for an ADU in Carlsbad?

A parking space is not required for an ADU in any of the following instances:

  • Within a one-half mile walking distance from public transit, which includes bus stops.
  • Within an established historic district.
  • Converted from the existing space of a primary residence or accessory structure, or are attached to an existing or proposed primary residence.
Where can a parking space be located?

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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