I'm with David Ward. I also have a home with 1/2 of the roof on the north, and 1/2 on the south. I live in Wisconsin, and after our last cold snap, we started seeing condensation problems. The entire northeast roof was wet on the inside! We, however, roofed our home three years ago, and did put down tar paper, and several layers of ice and water barrier. We have also insulated and added roof ventilation where none existed in the previous 75 years. What can we do??