Montebello, CA Accessory Structures: Shed & Carport Rules (2026)

Montebello Municipal Code Section 17.08.020 defines an "accessory building" as any detached structure, subordinate and incidental to the main building on the lot, covering things like sheds, garages, and rumpus or guest rooms. Outside of garages, an accessory building is capped at 500 square feet; any accessory space actually used for human habitation, such as a guest room or converted rumpus room, is treated as a habitable accessory building rather than a simple storage shed. Setbacks for these structures are set out in the Minimum Setback Requirements table at Section 17.10.040: a shed used for human habitation follows the same setbacks as the main house, 20 feet from a front street lot line, 10 feet from a rear lot line, and 5 feet from a side lot line.

A shed not used for human habitation gets more room to maneuver: it can sit with a zero setback from a side or rear lot line if the wall facing that line has no openings, or 5 feet if it does, and it needs no setback from a rear or side alley unless it's a garage opening onto that alley, which still needs 5 feet. Section 17.10.040(A)(1) also raises every setback by one foot for each three feet of building height above 15 feet. Section 17.10.050 layers on a separation rule between structures: any building used for human habitation must sit at least 10 feet from another building, and a shed or other accessory building must keep at least 10 feet from the main house unless it is built with one-hour fire-resistant construction throughout, which drops the required gap to 5 feet, provided that 5-foot strip stays open from the ground to the sky.