Temecula, CA Accessory Structures: ADU Rules (2026)

23, implements the state Accessory Dwelling Unit law while retaining the local design and dimensional standards state law still allows a city to set. 030(D)(3)-(5). 050(B)(1): an attached ADU added to an existing home cannot exceed fifty percent of that home's gross floor area, and a detached ADU, or an attached ADU built alongside a brand-new primary home, is capped at 1,200 square feet. The code carves out a floor beneath those caps: it cannot be used to block an 850-square-foot ADU, or a 1,000-square-foot ADU with more than one bedroom, regardless of the percentage math.

050(B)(2) tops out at sixteen feet for a standard detached ADU, rising to eighteen feet, twenty with a matching roof pitch, within a half-mile of a major transit stop, and to eighteen feet on a lot with an existing multistory multifamily building. 050(B)(5), with no setback required for an ADU built inside an existing structure's footprint. 040(E)-(F), with no public hearing and a state-driven sixty-day decision clock under Government Code Section 66317. 030(D).