Should I close attic vents in winter?
Why winter ventilation matters
A vented attic is supposed to stay close to outdoor temperature. Warm, moist house air leaks up through gaps in the ceiling, and when it meets a cold roof deck it condenses. On a cold, clear Georgia night the underside of the deck can drop below the dew point of that air, forming frost on nail tips and sheathing. When the sun hits the roof, the frost melts and drips.
What about heat loss?
The attic is not meant to hold heat; the insulation on the attic floor does that. Closing the vents does little for heating bills but a lot of harm with moisture. If upstairs rooms feel cold, check insulation depth and air sealing around lights, the hatch and plumbing chases.
Exceptions people ask about
- Whole house fan louvers: those are ceiling openings into the living space, not attic vents. An insulated winter cover over them is a good idea.
- Crawlspace vents: a different system with different rules.
- Gable vents next to a working ridge vent: blocking them is a year round improvement, not a winter fix, and only when intake is adequate.
- Sealed spray foam attics: already closed by design.
North Georgia note
Mountain counties see longer cold spells, and ice dams occasionally form there. Good ventilation plus insulation keeps the deck cold and even, which helps prevent them. Robust Roofing's guide to ice dams in North Georgia explains more. See ice and water shield in Georgia and roof ventilation basics.