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Roof & Attic Ventilation in Ottawa

Balanced roof and attic ventilation – intake and exhaust sized together to extend roof life, cut ice dams, and keep attic moisture under control.

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Certified, insured installers
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Serving all of Ottawa

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A roof needs to breathe

Ventilation is what makes a roof last

A roof is not just a waterproof layer – it is a system that has to let heat and moisture escape the attic. When ventilation is wrong or missing, the attic bakes the shingles from below in summer and traps moisture in winter, shortening the life of the whole roof and driving ice dams at the eaves. We assess whether your roof has adequate, balanced ventilation and correct it, so the roof lasts as long as the shingles are rated to.

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Why ventilation matters

Longer roof life

A cooler, drier attic stops shingles cooking from below, so the roof reaches its rated life.

Fewer ice dams

Balanced airflow keeps the roof deck cold and even, so snow does not melt and re-freeze at the eaves.

Less attic moisture

Moist air escapes instead of condensing on the sheathing, which prevents mould and rot.

Lower cooling bills

A vented attic runs cooler in summer, easing the load on your air conditioning.

Balanced intake and exhaust

Ventilation only works when air can flow in at the eaves and out at the peak. That means intake vents low in the soffits and exhaust vents – ridge or roof vents – up high, sized to match each other. A roof with exhaust vents but blocked or missing soffit intake does not actually breathe, no matter how many vents are on top. We check both sides and balance them, which is what actually moves air through the attic.

Ventilation and ice dams

Ice dams are one of the most visible symptoms of a ventilation problem. Warm air leaking and building up in the attic melts the underside of the snow, the meltwater runs down to the cold overhang, and it re-freezes into a dam that forces water back up under the shingles. Keeping the roof deck cold and even with balanced ventilation – together with proper attic insulation – is how you stop that cycle at the source rather than chipping ice off the eaves every winter.

Done with your roof or on its own

The cheapest time to get ventilation right is during a re-roof, when we can set the exhaust vents and confirm the intake as part of the job. But if your roof is sound and the attic simply is not breathing, we assess and correct the ventilation on its own. Ventilation and attic insulation go hand in hand, so we often look at both together.

Ventilation FAQs

What are the signs of poor roof ventilation?

Common signs are ice dams and icicles at the eaves in winter, a scorching-hot attic in summer, condensation, frost, or mould on the underside of the roof sheathing, musty attic smells, and shingles that wear out well before their rated life. Any of these usually points to a ventilation problem.

What is balanced ventilation?

It means the intake (usually soffit vents at the eaves) and the exhaust (ridge or roof vents near the peak) are sized to work together, so air flows in low and out high across the whole underside of the roof. Exhaust without enough intake – or the reverse – does not actually move air. Balancing the two is the key.

Does ventilation really help with ice dams?

Yes, it is half the fix, alongside attic insulation. Ice dams form when heat escaping into the attic melts snow that then re-freezes at the cold eaves. Balanced ventilation keeps the whole roof deck cold and even, so the melt-and-refreeze cycle that builds ice dams does not get started.

Can you add ventilation with my new roof?

Yes, and it is the ideal time – we set the correct intake and exhaust as part of the re-roof. We also assess and improve ventilation on its own if your current roof is fine but the attic is not breathing.

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