I have a home in Minnesota where there are ice dams building up and causing leaking inside. I want to fix the issue and not just put a band aid on it but I'm not sure how. Everywhere I have read says that there is not enough ventilation in the areas where the dams are forming. The problem I have is that the home is a 1.5 story and the 2nd floor is finished, but there are dormers (Crawl space between the bedroom wall and roof) surrounding the perimeter of the house (for the most part). The people who owned the home before me installed blown in insulation between the roofing and the bottom of the roof 2x4's (so basically 3 1/2" of insulation) and put cardboard up to keep the insulation in place. With the way they did this there is no air movement because the edge of the roof is packed with insulation. This is where I'm stuck on what to do to get ventilation through there. I don't want to completely open it up permanently because there is a bedroom and a den up there and I need it to stay warm. Any ideas on how to get that area ventilated without loosing heat in the rest of the living area?