Mesa, AZ Accessory Structures: Garage Conversions (2026)

Under § 11-31-3(D)(2), an existing detached accessory building or structure that already complies with the setback requirements for detached accessory buildings in Section 11-30-17 can be converted into an ADU without triggering the newer, larger 5-foot side/rear ADU setback in § 11-31-3(D)(1); it keeps whatever setback it legally has. Even a legal non-conforming detached structure that doesn't meet either the § 11-30-17 or § 11-31-3(D)(1) setbacks can still be converted to an ADU without adding setbacks, though any expansion built to accommodate the ADU must either meet the standard ADU setback or hold the line at the existing non-conforming setback without making the non-conformity worse.

On the parking side, § 11-31-3(G) removes the usual consequence of losing a garage: no additional parking spaces are required for an ADU in the first place, and if a garage or carport is converted into the ADU itself, the covered parking that garage or carport provided for the primary residence does not have to be replaced anywhere else on the lot. The converted unit still has to meet the ADU's other standards regardless of its garage origin, a separate, independent entrance with no interior connection to the primary residence, no more than one kitchen, compliance with residential building code, and, for detached units, height limits matching the accessory-building standards in § 11-30-17 for any uninhabitable space carried over from the garage.