Q: Should I turn off my attic power fan and close the vents during winter?
A: Although the natural instinct to keep the house warmer may be to close the attic vents, that is definitely not a good idea. In fact a cold, drafty attic is the ideal condition for an attic during winter. Insulation is what protects the house interior from this cold attic zone. A cool attic is the best way to control moisture. The chimney effect causes heat to rise into the attic, and this warm air can hold more moisture than cold air. When that warm air cools it releases vapor as condensation, which is why you want to vent it outside. When the attic ventilation can’t sufficiently dry the condensation, the house can develop mildew, wood rot, peeling paint and other problems.