See: http://buildingscience.com/documents/insights/bsi-046-dam-ice-dam http://buildingscience.com/documents/insights/bsi-046-dam-ic... The snow melts because o

See: http://buildingscience.com/documents/insights/bsi-046-dam-ice-dam http://buildingscience.com/documents/insights/bsi-046-dam-ic... The snow melts because of heat coming from the inside the house. [1] So if you keep your roof cold through insulation and ventilation, you don't need to remove the snow (as long as the roof can handle it structurally) [1]: http://www.erdc.usace.army.mil/Portals/55/docs/CEERD-RV/CEERD-RR-H/BuildingTechnology/ResearchPapers/MP-02-5778,%20Guidelines%20for%20Ventilating%20Attics%20and%20Cathedral%20Ceilings%20to%20Avoid%20Icings%20at%20Their%20Eaves.pdf http://www.erdc.usace.army.mil/Portals/55/docs/CEERD-RV/CEER... [pdf]