Should Attic Vents Be Blocked in Winter?

Benefits

• You might think it counterproductive to insulate an attic to save on energy costs and then let cold air flow through the vents, but Energy Star states that this air is necessary to prevent other damage to your home. When you allow a natural flow of air in the winter, the attic stays cold, which reduces ice damming. Ice damming refers to snow melting off the roof and then refreezing in the gutters. This causes an ice dam, which can hurt your roof. If your attic gets too warm, the potential for ice damming increases. Ice damming is most common in homes with complicated roofs with several valleys or those with large overhangs. So, opening vents allows for cold air to move more freely.

Adding Insulation

• Insulation is one way to keep your attic cold and prevent ice damming. This also helps keep heated air in the actual house, where it belongs, which could reduce energy costs. Fiberglass insulation rolls are the easiest way to add insulation to the attic. If your attic already has insulation, you can add another layer, but is should be placed perpendicular over the original layer. Never cover your vents with insulation.

  To completely cover your attic's floor with insulation, you can install rafter vents. These attach to the wall and help increase airflow in the room.

Airflow with Fans

• Attic fans are one way to help with airflow in the attic. If you cover your vents, the air released from your furnace or air conditioner will be sucked into your attic, which will cause the appliance to run more and increase your energy costs.

Considerations

• Though it is best to keep your attic vents flowing year-round, damp coastal climates might be drier with less ventilation, the Canada Mortgage and Housing Corporation states. Check your local building codes for recommendations that will be specific to your area's climate. If you are building a home and live in an area that gets a lot of snow, design the roof to resist ice damming, if possible.