An air duct system is configured to be used with an air containment system that spans an aisle defined by rows of racks. The air duct system includes a plurality of ceiling panels supported by the air containment system, and a plurality of support curbs mounted on the ceiling panels. The plurality of support curbs is configured to support ductwork positioned on the support curbs, ductwork positioned on the plurality of support curbs. The air duct system further includes a plurality of panels secured to the support curbs to create a plenum underneath the ductwork. A kit providing an air duct system is further disclosed.