[HayZee518]

anyplace you see sheets of aluminum or galvanized sheeting stapled to basement joist, you can be guaranteed they're cold air returns. something I learned while on the job, to hold something to poured concrete or concrete blocks, get a real small masonary drill bit. drill through both the material and the concrete or blocl almost full length of the drill. Now stick a piece of iron tie wire in there and drive an 8 penny nail into the hole. make it into an L shape before you put in the nail. I'll make a bet you can't pull out the nail. cheaper too!