Ventilation

Winter conditions bring a different set of challenges. During the cold season, the air inside your home is warmer and contains more water vapour than the cold, dry air in the attic.

Humidifiers, cooking, laundry, showers, and other water-related activities all contribute to this imbalance.

A powerful natural phenomenon known as vapour pressure drives moisture from high-humidity areas toward low-humidity ones. Water vapour can pass through ceilings, insulation, and even wood, sometimes bypassing vapour barriers entirely.

It slips into the attic and condenses into liquid upon contact with framing components—rafters, trusses, and especially the roof decking—which are significantly colder.

Condensation in the attic or ceiling void can compress and dampen the insulation, reducing its R-value and speeding up heat transfer into the attic. This cycle can ultimately lead to mould, rot, ice dams, and more.

In summer, trapped heat in the attic acts like a heating system. That heat transfers to the ceiling insulation, warming the ceiling itself. It then radiates into nearby living spaces, making upper floors hotter than those below.

This heat also causes shingle distortion, buckling of the roof deck, and other material failures. As a result, your air conditioner has to work overtime to cool the living areas.