Frost development in an attic is the result of heat that is moving up through the insulation into the cold attic. More often than not you may find that the heat is coming from a vent that is pumping warm moist air into the attic. On extremely cold days or days of vast swings in temperature you may see some frost. A little frost is inevitable on these types of days and should not create any issues. Excessive frost can cause stains in ceilings and even mold. Another cause of frost and even ice damming is lack of adequate venting in the attic. Make sure your attic has soffit, gable and roof vents if possible. Older homes often didn’t have any soffits so adding gable vents and roof vents is best in that case.Frost in ceiling