Attics should be well ventilated and heavily insulated in order to prevent moisture problems in the winter and spring. As warm air rises inside the house it will escape into the attic space, as the warm air meets the cold roof sheathing, it condenses and freezes. When warmer outside temperatures happen during a chinook or in the spring, the ice melts and causes stains on the ceiling inside the house. This problem known as attic rain can cause headaches for homeowners. Having a properly insulated attic space prevents warm air from escaping into the attic space causing attic rain and ice damming. A well ventilated attic space will allow warm air to escape through the roof and not accumulate on cold surfaces inside the attic. A good home inspector should point this out during an inspection when/if ventilation or insulation conditions are poor.