Whittier, CA Accessory Structures: ADU Rules (2026)

020(I) of the Whittier Municipal Code sets the development standards for accessory dwelling units (ADUs) citywide. On height, subsection (I)(5)(f) allows "a height of sixteen feet for a detached accessory dwelling unit on a lot with an existing or proposed single-family or multifamily dwelling unit," rising to eighteen feet, plus an extra two feet to match a roof pitch, if the lot sits within one-half mile walking distance of a major transit stop or high-quality transit corridor as defined by Public Resources Code Section 21155; the code allows a further height increase up to twenty-five feet for a unit attached to the primary dwelling, capped at whatever the underlying zone's height limit is for the primary residence, whichever is lower.

On setbacks, subsection (I)(4)(b) requires no setback at all when an ADU converts existing living area or an existing accessory building, or replicates an existing lawful structure's footprint; every other detached ADU needs a minimum four-foot setback from interior side and rear lot lines, and the city cannot enforce even that minimum if doing so would prevent building at least an eight-hundred-square-foot unit, with first placement priority given to the rear of the lot. ADUs may reach a second story above a garage or accessory building under further conditions in subsection (I)(5)(g), and building code, easement, utility-connection, architectural and historic-preservation standards in subsection (5) apply to every unit regardless of size.