An aisle containment system installed around a pre-existing building column in a data center. The aisle containment system includes a frame defined by wall beams, header frames, and a plurality of posts. A plurality of cabinets are positioned within the frame. Mid-span posts are positioned adjacent building columns located within the frame. The mid-span posts support the wall beams on one side of the frame. A containment column adapter is secured to one of the wall beams and one of the mid-span posts. The containment column adapter seals the gaps between the building column and the wall beam within the frame of the aisle containment system.