Lets talk about the thing that we get to see alot of in the northeast. Ice dams are where an improperly sealed and insulate part of a home on an incline is heating too much space above it and slowly the water drips down the roof of the house til it meets the end of it. There an unheated portion of the roof is solid ice and builds a dam. Now this dam can be best eliminated by taking time to properly seal up the attic space and then in turn insulating the attic space, or wall space more. How much more? Well, I know that in my area of the northeast USA I would not be happy without adleast R-50 in my attic space. If you are having problems with ice dams, air seal first, insulate second, and then if none of that works finally call to have the wires or the flashing installed on the roof.