We moved into our home last year. The former owner studded out the basement walls, including wired outlets and light switches, and left a 1 1/2 inch space between the 2 x 4's and the walls, which are poured concrete. All that's left to do is insulate and install wallboard. My question is, why the space behind the studs? I assume it's for ventilation to prevent moisture build-up from the concrete walls, but I can't find a method like this on any instructional videos. Is this an acceptable method of construction or did he not know what he was doing? Also, it takes away about 5 1/2 inches around the perimeter of the room.