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
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.
Setbacks
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.
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.
What is the minimum distance the ADU must be from existing structures?
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 last 10 feet away from other buildings used for human habitation.
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.
Multifamily
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.
Parking
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.
Additional Carlsbad ADU Regulation Resources
City of Carlsbad Info Bulletin – IB-111 – Accessory dwelling units
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