How to Properly Ventilate Attics in Cold Climates

While roof maintenance extends the life of the roof itself, proper attic ventilation helps make the roof system last longer, and spare you from expensive problems that may occur inside and outside of a building. In places with cold climate, ventilation helps avoid ice damming. Suffice to say that proper ventilation in the attic will prove advantageous to homeowners.

Benefits of proper ventilation

  • Reduce moisture damage that can quickly build up in the attic, resulting in potential structural damage, degradation of the roof system, and mold.
  • Reduce energy consumption by ensuring warm air stays indoors, saving the heater from working doubly hard. During the summer months, proper attic ventilation protects the home’s air conditioning from working harder.
  • Protect roof shingles from damage, especially during summer when high attic heat can bake the shingle, resulting in premature aging.

Understanding proper attic ventilation

There are two approaches to ventilation – vented and unvented. The former has long been proven effective and works seamlessly with roof construction, while the latter is a fairly new concept that is said to be energy saving and provides bigger payoffs. The only downside is that the roof shingles may not last quite as long as when the attic is vented.

Energy saving or not, most professionals still recommend a vented approach for the simple reason that it will work in various climates – hot, mixed and cold. When executed properly, it will be just as effective in the Arctic as it will be in the Amazon.

The primary purpose of ventilation in cold climates is to maintain a cold roof temperature, which is the best way to prevent ice dams from forming due to melting snow. It is also built to vent any moisture that moves from conditioned areas of your home into the attic.

Vent the Attic 101

  1. Make sure that the ceiling of the top level of the house is airtight before insulation is installed.
  2. Make sure the attic floor is sealed completely.
  3. Leave plenty of airspace between the roof and the insulation.
  4. There should be nothing in the attic, except insulation and lots of air. If an attic is used as a storage space, an elevated platform must be built above the insulation, and entry to the attic must be airtight to prevent leakage.
  5. When adding recessed lights, mechanical systems with air handlers, or ductworks, they should be air-sealed very well to prevent energy wastage and humidity problems. Don’t rely on duct sealing alone, as it is only capable of bringing down leakage to 5%, which is still not good enough. Make sure a builder air-seals the entire area.
  6. As much as possible, mechanical systems or ductwork should be built outside of the attic space. If this is not possible, the entire area should be kept inside a thermal envelope.

Attic soffit vents must be free of insulation, so air can flow freely at the eaves. Use rafter vents with soffit vents to ensure there is enough room for air to into the soffits, and to maintain air flow.