Ventilation is a huge problem for roofs especially in the winter time. Most homeowner think mold is created during the summer time but here is good example. During the winter on a cold day someone will take a shower, boil water, have unvented drier basically create steam in the house. Steam rises past the cieling into unvented attic or improperly install ridge vent and soffit vent. The steam contacts the cold roof and freezes. then turns to liquid form when the temperture outside raise or you turn your heat up. This constant process will create mold and other problems. Check out this link on <Company link removed>
Last edited by beenthere; 05-14-2013 at 06:53 AM.
Reason: Removed link to his company