Alhambra, CA Accessory Structures: ADU Rules (2026)

Alhambra adopted its own ADU/JADU standards in Zoning Code Section 23.22.040 (most recently updated by Ordinance O2M25-4844, adopted April 2025) to implement California's statewide ADU law, Government Code 66310 through 66342. The City recognizes three types: detached ADUs separate from the main home, attached ADUs built onto or within the primary structure, and junior ADUs (JADUs) converted from existing space entirely inside a single-family dwelling. On single-family lots, detached ADUs may be up to 1,200 sq ft; attached ADUs are limited to 50% of the main unit or 850 sq ft (one bedroom or less) / 1,000 sq ft (two or more bedrooms); JADUs are capped at 500 sq ft. Maximum height is two stories / 25 feet, with a minimum 4-foot side and rear setback for new units. One additional parking space is required unless the ADU is within one-half mile of transit, on a historic property, or a conversion of existing space; JADUs require no added parking. ADUs must generally match the main dwelling's exterior materials, roof, and colors. Per the City, ADUs and JADUs are prohibited from short-term rental use under Chapter 5.92. Most ADUs are processed ministerially through the Building Division without a discretionary planning application.