Fullerton, California


When it comes to adding an extra unit to your home, many homeowners in Fullerton are turning to building ADUs. These accessory dwelling units can provide much-needed extra space for guests, family members, or even renters. And, because they’re typically built on existing properties, they can be a more affordable option than buying a new home or building a new home.


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
  • Not to exceed 1,200 sq. ft. max for a detached ADU
  • Attached ADU Max Size: 1,000 sq. ft. or 50% of floor area of primary dwelling, whichever is greater, not to exceed 1,200 sq. ft.

Building height

Attached or detached ADUs shall comply with the height standards applicable to the zone in which it is located. Limited to height allowed in the zone One-story 20 feet above natural grade Two-story 30 feet above natural grade


One parking space is required for an ADU with one or more bedrooms unless property meets provisions to waive parking requirement.

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