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All ADU Regulations

El Cajon, California

El Cajon has updated its ADU ordinance to comply with new state laws. Below are the up-to-date requirements for permitting an ADU in El Cajon
Updated Jul 27, 2022

El Cajon

El Cajon is a city in San Diego County, California. The city, which is also east of downtown San Diego, has a long history as a bedroom community for San Diego. In recent years, the city has been working to revitalize its downtown area. Part of this effort has been to encourage the development of accessory dwelling units (ADUs).
ADUs are a type of housing that is typically attached to or built on the same property as a single-family home. They can take many forms, such as a converted garage. Cottage can help you build your ADU!


All properties zoned for single family and multifamily use may be eligible to build ADUs.

Number of units

The number of ADUs you’re able to build depends on how your lot is zoned:
  • Lots zoned for single family use may add 1 ADU and 1 Jr. ADU (JADU).
  • Lots zoned for multi-family may add 2 new detached ADUs and at least one conversion ADU (interior conversion of existing building, but no more than 25% of the original number of units. (E.g. an apartment with 4 units may add 2 detached ADUs and 1 conversion ADU.)

Building size

  • The maximum size is 500.0 sq. ft. for a JADU
  • 850sq. ft. max for a detached ADU
  • Attached ADU Max Size: 1200 or 50% of the primary dwelling square footage, whichever is less

Building height

Building height for attached and detached ADUs is: 20ft, an ADU taking advantage of the 4′ setbacks cannot exceed a height of 16 feet.


State Law - No requirements for parking if any of the following true:
  • The accessory dwelling unit is located within one-half mile walking distance of public transit.
  • The accessory dwelling unit is located within an architecturally and historically significant historic district.
  • The accessory dwelling unit is part of the proposed or existing primary residence or an accessory structure.
  • When on-street parking permits are required but not offered to the occupant of the accessory dwelling unit.
  • When there is a car share vehicle located within one block of the accessory dwelling unit.


  • Owner occupancy not required
  • No short term rentals (<30 days)
  • No sale of the ADU separate from the main home

Want to learn more about ADU regulations in your area?

Book a free consultation and estimate with a Cottage ADU Expert to find out what’s possible on your property!