Proper attic and roof ventilation design and installation for residential properties in Greater Montreal. Prevent ice dams, reduce energy costs, and extend roof life.
Adequate roof ventilation is one of the most important and most overlooked factors in roof performance and longevity, particularly in Quebec's demanding climate. A properly ventilated attic maintains a temperature close to the outside air, which prevents the uneven snowmelt that causes ice dams in winter and reduces excessive heat buildup that accelerates shingle deterioration in summer. The Quebec building code specifies minimum ventilation ratios for residential construction, but many older homes fall well short of these requirements.
Roof ventilation works on a simple principle: cool outside air enters through intake vents at the soffits (the underside of the roof overhang) and exits through exhaust vents near the ridge. This continuous airflow removes moisture-laden air from the attic before it can condense on cold surfaces, and it carries away heat that would otherwise accumulate under the roof deck. Both functions are critical in Quebec. Moisture condensation in the attic causes wood rot, mold growth, and insulation degradation. Heat buildup melts snow unevenly and creates ice dams.
We install and upgrade several types of ventilation components. Soffit vents provide intake air and come in continuous strip, individual round, and rectangular configurations. Ridge vents run along the peak of the roof and provide exhaust without the visual impact of individual roof vents. Turbine vents and powered attic ventilators are options for situations where passive ventilation alone cannot achieve adequate airflow. We also install gable vents and roof-mounted static vents where they are the most practical solution.
Balancing intake and exhaust is essential. A common mistake is installing ridge vents or roof vents without adequate soffit intake, which creates negative pressure in the attic and can actually pull conditioned air from the living space through ceiling penetrations. Our ventilation assessments calculate the required airflow for your attic volume and roof configuration, then design a system that achieves balanced, effective ventilation. For homes with cathedral ceilings, knee walls, or complex roof geometries, we develop solutions that maintain airflow through these challenging configurations.
Why this service
Prevents ice dam formation by keeping the roof deck cold
Reduces summer heat buildup in the attic
Prevents moisture condensation, mold, and wood rot
Extends the life of roofing materials
Lowers heating and cooling energy costs
Balanced intake and exhaust design
FAQ for this service
When the attic is too warm from inadequate ventilation, it heats the roof deck and melts snow from below. The meltwater runs down to the cold eaves (which hang past the heated space) and refreezes into an ice dam. Proper ventilation keeps the entire roof deck at a uniform cold temperature, preventing this cycle.
The Quebec building code generally requires a minimum net free ventilation area of 1/300 of the insulated ceiling area, with ventilation split roughly equally between intake (soffit) and exhaust (ridge or roof). Actual requirements can vary based on roof geometry, vapor barrier quality, and other factors.
Common signs include ice dams in winter, excessive heat in the attic during summer, moisture or frost on the underside of the roof sheathing, mold growth in the attic, peeling paint on exterior soffits and fascia, and premature aging or curling of roof shingles.
Yes. Ridge vents are nearly invisible from the ground and provide excellent exhaust ventilation. Continuous soffit vents can be installed in the existing soffit material with minimal visual change. These low-profile options improve ventilation significantly without altering the appearance of the home.
Roof replacement is the ideal time to upgrade ventilation because the roof surface is already open. Adding ridge vents, improving soffit intake, and correcting any ventilation deficiencies costs less during replacement than as a separate project. We include a ventilation assessment with every replacement quote.