Gardena, CA Accessory Structures: ADU Rules (2026)

Chapter 18.13 of the Gardena Municipal Code governs accessory dwelling units citywide, consistent with California Government Code Sections 66310 through 66342. Section 18.13.030 allows an ADU on any legally existing residential lot with a single-family or multifamily dwelling, and on mixed-use lots with residential use, built attached, detached, or converted from an existing garage or accessory structure. Section 18.13.050 sets the size, setback and height standards: an attached or detached ADU cannot exceed eight hundred fifty square feet for a studio or one bedroom, or one thousand square feet for a unit with more than one bedroom, and no ADU may be smaller than the state efficiency-unit minimum.

Setbacks are four feet for side and rear yards on most new ADUs, with no setback required for a unit built in the same footprint as an existing structure, and an ADU must sit at least six feet from any other building on the lot. Height runs sixteen feet for a detached ADU on most lots, eighteen feet within a half-mile of a major transit stop, and up to twenty-five feet, matching the R-1 primary-dwelling limit, for an ADU attached to the house or built above an existing garage, never more than two stories.

Section 18.13.020 requires the city to approve or deny a complete ADU application ministerially within sixty days, and Section 18.13.040(A) limits a lot to one ADU unless Section 18.13.060 authorizes more, such as up to two detached units on a lot with a proposed multifamily building.