City of San Diego ADU Regulations & Zoning

San Diego Prefab ADU Home


What is all the buzz about ADUs in San Diego? Want to learn about The City of San Diego ADU regulations? An ADU is an Accessory Dwelling Unit (aka Granny Flat or a small home) that can be built in your backyard and used for extended family or friends or as a rental property. It can be attached or detached from the main house.

The State of California is leading the nation in ADU development and regulations, and a great summary can be seen in the ADU handbook published by the State of California.

One of the most affordable types of ADUs is a prefabricated home. One of San Diego’s most active prefabricated ADU builders in San Diego is USModular Inc. “ADUs are becoming very popular for homeowners looking to generate rental income in their backyard or for families that have children or elderly parents moving home, as it gives everybody their own space, is affordable and ADU increases the value of the property,” says Todd Kesseler, CEO of USModular Inc.


Some of the Highlights of the State of California ADU Regulations Include:

  • Every residential property in California is allowed to have one ADU of up to 800 sq ft regardless of lot size, floor area ratio, or main residence size.
  • This ADU can be up to 16 ft in height.
  • Homeowners are allowed to build one attached ADU or one detached ADU and one JADU, all on the same property.
  • Cities must allow at least 850 sq ft for one-bedroom ADUs and at least 1,000 if the ADU has two or more bedrooms. Cities cannot impose smaller max sizes, but they can impose larger. Every City has specific regulations for size and bedroom count above 800.
  • Setbacks – Most cities have side yard and rear yard setbacks at 4’, but there are some cities that allow 0’ setbacks, and some areas have fire department regulations that require 5’ setbacks – the bottom line is side and rear yard setbacks are much smaller now for ADUs.
  • Parking – Most cities want to see 1 off-street parking space on your property for the ADU, except when your home is located within ½ mile to public transit
  • Fire Sprinklers are required if the Main house has them or if ADU is not close to a fire hydrant.
    Multifamily properties are allowed multiple ADUs
    Solar panels are not required for prefabricated ADUs but may be required on a site-built ADU
  • Condo your ADU – This is a new State of Ca law, and if/when adopted by cities – you will be allowed to sell your ADU as a separate unit.


ADU Regulations in San Diego are Some of the Most Progressive in the State of California!

Beyond established regulations by the State of California, ADU regulations in San Diego will allow multiple ADUs in specific transit districts and will also allow Tiny Homes as ADUs.

  • San Diego, CA, has a population of 1,419,845
  • Median property value: $ 622,300
  • Single-family properties: 287,927
  • Persons per household: 2.68
  • Median rental value: $ 2,779
  • Multi-family properties: 246,462

Based on San Diego’s population, the number of Single-Family Homes, Multifamily Properties and Rental Value, there is a lot of opportunity for ADU construction in San Diego.

Review City of San Diego ADU Regulations
City Of San Diego ADU Handbook

What is Prefabricated Construction?

  • Prefabricated construction means homes are built off-site in a factory, just like your car and most of every other item you use daily.
  • Prefabricated Homes are also known as Manufactured Homes and Modular Homes. Prefabricated Home plans are pre-approved by the State of California.
  • These homes are designed, reviewed, approved and inspected by the State of California.
  • The main benefits of Prefabricated Homes are they are less costly, faster to build in factories and have less impact on homeowners and neighbors.


FAQs About ADUs in San Diego, CA

Here are the answers to common questions that San Diego homeowners ask when considering adding an accessory dwelling unit (ADU) to their property.

What Are San Diego’s ADU Zoning Requirements?

ADUs are allowed in all residential zones. They must be placed on single-family or multi-family residential zoned lots. If your area is in a Coastal Overlay Zone, there may be additional regulations to comply with that are in place to help protect our coasts.

What is the ADU Lot Size Requirement?

There is no minimum lot size requirement for an ADU in San Diego.

  • Only one ADU is allowed per single-family lot and up to 2 ADUs for a multi-family lot.
  • Other non-residential structures, such as sheds or garages, may be allowed.
  • An ADU should be at least 6 feet from other residential buildings.
  • Construction of a passageway is not required when building a companion unit.


What is the Min/Max ADU Size Limit in San Diego?

Your ADU size limit in San Diego differs depending on whether your accessory dwelling 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 you have an existing house of 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.
  • Note: The floor area of the ADU should be included when calculating the total floor area of the lot.


According to ADU Regulations in San Diego, is a Parking Space Needed?

ADUs should follow the same parking regulations as the main house. If there was parking access from an alley before, it should still be accessible after building a companion unit unless there is a garage.

There are many options for parking spaces. They may be put within setback areas, covered or uncovered, or use mechanical lifts. The important thing is that they provide safe and efficient vehicle access. The minimum parking requirement is one parking space per companion unit, with 0.5 parking spots per bedroom.

According to ADU regulations in San Diego, parking space is not required if the ADU is:

  • 500 square feet or less
  • Located within half a mile of transit
  • Located in a historical resource area
  • Already part of the existing building
  • Located in a residential permit parking district
  • Located within one block of a car share station
  • Located within one block of a bike share station


What are the ADU Setback Requirements in San Diego, CA

A setback is a minimum distance a structure must be away from the street, buildings, or other features. ADU setback requirements in San Diego have shrunk the side and rear yard setbacks to 4’.

What Are the City of San Diego’s ADU Requirements For Owner Occupancy?

San Diego ADU requirements stipulate that a companion unit can’t be sold separately from the main house. The owner does not need to live in the main or companion units; both structures can be rented.

What are the Renting ADU Rules in San Diego?

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 and cannot be rented out for less than 30 consecutive days.

What are ADU Junior Units?

An ADU junior unit is an accessory structure that is contained entirely within the main house. They are exempt from parking regulations and should have a separate outdoor entry, a connection to the main living area, and should include an efficient kitchen. They may have a bathroom or share it with the main house. The junior unit and the main house must be sold together, and the owner must live in either the junior unit or the main house.

Do Accessory Dwelling Units Add Value to Home in San Diego?

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 is 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 family.

USModular Inc. is a premier contractor of prefabricated homes and ADUs with over 40 years of experience in the industry. You can see the available floor plans and pricing at
Toll-Free: (888) 987-6638
Local: (951) 679-9907 Ext. 1

Check out our latest ADU projects!


US Modular

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