Many homeowners think it’s a good idea to cover their attic vents in winter. They do this because drafts enter their home through the vents, making their indoor environment too cold so their furnace has to work harder to make rooms warmer.
However, open and functional vents are very important during the winter season because vents prevent moisture from collecting in your attic.
Problems Associated With Blocked or Closed Vents
- Moisture in your attic is the product of condensation or frost. When temperatures drop, the heated air in your home can get trapped in your attic. When that hot air hits the cold surfaces in the attic, the vapor in the air turns to moisture. Without attic ventilation, the moisture-rich air has nowhere to go. With proper attic ventilation, outdoor air can push the air in the attic out, preventing frost buildup in your roofing system.
- When moisture is trapped in your attic, it becomes the ideal environment for mold and mildew growth. Mold and mildew present a health risk to your household, and they can deeply affect your home’s structure.
- Wood rot, which is another term for wood decay, can affect all wood components of your roofing system. It can also migrate to your ceiling, drywall and other surfaces of your home. Rot can compromise your roof’s structural integrity, and repairing it is costly and extensive.
- Ice dams can form on the edges of your roof if your attic vents are closed. This happens when too much heated air is trapped in the attic. The part of your roof near the ridge is the hottest because heat naturally rises in a process called convection. The snow outside that surface melts and flows to the gutters. Before it reaches the gutters, however, it travels onto the lower and colder surfaces at the edge of the roof, causing the water to freeze into ice dams. The ice dams will prevent more water from draining. With nowhere to go, the water will eventually enter the smallest crevices and cracks, including the bottom part of shingles, leading to leaks. Even if your roof doesn’t leak yet, when the water in the crevices and cracks freezes, it will force the opening to get bigger.
To prevent such expensive roofing problems, make sure your attic has ample ventilation. If you’re concerned about drafts, check your windows and doors. As for your attic, add more insulation.