Imperial Beach 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.

Zoning in Imperial Beach, CA

ADUs are allowed in lots zoned for single-family or multi-family use. A single-family dwelling must already exist on the property or be built simultaneously with the ADU.

Lot size

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

Min/Max Building Sizes

Your maximum build size differs depending on whether your accessory unit is attached or detached from the primary home.

Attached ADU: The floor area of the ADU should not be more than 50% of the existing residence up to 1,200 square feet. For example, if your existing house in 2,500 sq. ft., the attached ADU cannot exceed 1,200 sq. ft. in size.

Detached ADU: For a detached ADU, the total floor space area of the ADU should not be more than 1,200 square feet, regardless of the size of the primary residence.

Height Restrictions

Reference local building code.

Parking in Imperial Beach, CA

Detached ADU’s are required to have one parking space per bedroom or unit. Off street parking is allowed to be tandem or within the residence’s setbacks given that it is safe to access.

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


Attached ADU’s built within the existing residence do not require additional parking.


A setback is a minimum distance a structure must be away from the street, buildings, or other features.

When an existing garage is converted to an ADU, no additional setbacks are required (given it complies with fire and safety regulations).

For ADU’s constructed above a garage, the setback requirements are five feet from the side and rear lot lines.

Owner Occupancy

ADU’s cannot be sold separately from the primary residence. The owner is not required to live in the main residence or the ADU.


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. Local government decides if short-term rentals allowed

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 $275 a square foot, but the average value of homes in your neighborhood are worth $400 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 the family.

Additional notes

  • Fire sprinklers are not required in ADUs if they not required in the main residence.
  • The building of a passageway is not required.

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