Attic Ventilation & Ice Dam Prevention in Halton Region

Ice dams form along roof eaves when conditioned indoor heat escapes into the attic space, melting the underside of the snowpack on the upper roof deck.

The Balanced Attic Formula

An effective residential attic requires balanced intake and exhaust:

• Soffit Baffles (Intake): Clear paths along the eaves allowing cold exterior air to enter without blowing insulation away from the top wall plate.
• Ridge & Box Vents (Exhaust): High-level vents that release warm moisture-laden air before it condenses on cold plywood sheathing.
• Target Insulation Levels: Ontario Building Code recommends a minimum of R-60 blown insulation depth in unfinished attic spaces.