We are having problems with ice dams so I'm looking at our our attic is insulated. We have a story and a half house so the upstairs has knee walls with several crawlspaces scattered around the floor. My wife loves watching home renovation shows and I noticed that most of the time they seem to put insulation on the floor (providing it's a finished and heated room below) but not along the roof. We seem to have insulation in both places. Can it hurt to have the additional insulation along the roof?