I use the pink insulation board covered with flannel fabric secured with push pins at the edge of the board. It stays up on the wall because it is the same width as the wall so it is held in place by the door molding on one side and the wall corner on the other side. I have it only as high as I can reach, but it makes sense to have it high enough for the ceiling to hold the top of it in place. In my previous home I used heavy duty double sticky stuff on the back, but don't need it here. I like the foam because I can stick pins in it. Mine stays on the wall, but it would be simple enough to take it down if necessary.