Carlsbad, CA Accessory Dwelling Unit Regulations

Introduction to Accessory Dwelling Units

An accessory dwelling unit, commonly called a granny flat or in-law suite must exist on a lot that’s zoned single-family. It has its own entrance, separate from the primary house, as well as a kitchen, bathroom and living space. These units can be rented, year-round, and add a lot of value to a property.


ADUs are allowed in lots zoned for residential use. The lot must contain a single one family dwelling. There should be no other dwellings on the lot. ADU in coastal zone requires additional permits. This process is lengthier and is more expensive. However, coastal zones are highly desirable for long-term renters as well as dramatically increasing the property value of the home.

Lot size

There is no minimum or maximum lot size requirement in Carlsbad to build an accessory dwelling unit.

Min/Max Building Sizes

Carlsbad differs from the state law by prohibitively restricting the maximum size an accessory dwelling unit may be.

Detached ADUs: should not exceed 640 square feet.

Attached ADUs: total floor area should not be more than 50% of the existing residence. The total floor space area of the ADU should not be more than 640 square feet.

Height Restrictions

Attached ADUs should follow the height limits of the lot’s zone.

Detached ADUs are limited to one story in height.

An ADU above a garage is limited to two stories, including the garage.


Any parking space lost during construction of ADU (either by garage conversion, or destruction in the process of ADU construction) must be replaced.

Parking not required if the ADU is:

  • Located within ½ mile of public transit
  • Located within an architecturally and historically significant historic district
  • Part of an existing primary residence or an existing accessory structure
  • In an area where on-street parking permits are required, but not offered to the occupant of the ADU
  • Is located within one block of a car share area


The setback requirements are dependent on the zone of the lot.

There are no setback requirements for ADUs converted from an existing garage.

A setback of 5 feet from the side and rear lot lines are required for ADUs above a garage.

Additional regulations apply for ADUs in coastal zones.

Owner Occupancy in Carlsbad, CA

The owner must reside in either primary residence or ADU unless both primary residence and ADU are leased to a single person.

ADU’s cannot be sold separately from the primary residence.

Rentals in Carlsbad

California passed Senate Bill 1069 in an effort to increase the supply of housing to the state. For this reason, any accessory dwelling unit may be used for a long-term rental.

How to Evaluate ROI

Building an accessory dwelling unit, especially if you intend to keep the property for a few years, represents an enormously beneficial opportunity to maximize your property.

By constructing an accessory dwelling unit you are adding additional square footage to the property. So if you can build a unit for $250 a square foot, but the average value of homes in your neighborhood are worth $401 a square foot you are gaining instant equity through the project. Plus, you also now have the added benefit of a flexible space that can be rented or used for family.

Additional notes

ADU should be architecturally similar to the main residence in terms of appearance, materials and finished quality.

Contact us today at 888-987-6638 or

Call Now Button