Pinal County, AZ Accessory Structures: ADU Rules (2026)

240 lets a single-family lot carry a primary dwelling plus one attached and one detached accessory dwelling unit if the parcel is under one acre, or two detached ADUs on top of the primary house if the parcel is one acre or larger. The code defines an ADU as a self-contained living unit on the same lot as a larger single-family dwelling, with its own sleeping and sanitation facilities and, optionally, its own kitchen. Size is capped by lot size: on parcels under an acre an ADU cannot exceed 75 percent of the main house's gross floor area or 1,000 square feet, whichever is less; on parcels an acre or larger the cap rises to 75 percent of the main house's gross livable area or 1,500 square feet, whichever is less.

Every ADU must sit at least five feet from the rear and side property lines and, if detached, at least seven feet from the main house, and must be a minimum of 200 square feet. An ADU shares the same street access and utility meters as the primary dwelling and cannot be addressed as a separate property, though it must carry its own unit house number. 03 allows, and no ADU may be built over a utility easement without the utility's written consent. Septic-served ADUs must have an adequately sized system approved before construction. The rule does not apply on tribal land or in high-noise or accident-potential zones near military or FAA-licensed airports.