Attic Ventilation, Toronto

Intake and exhaust, in balance

An attic breathes from the soffit up to the ridge. Block the soffit and the ridge vent starts pulling its make-up air out of the house instead, through every ceiling gap, which costs you heat and can backdraft a gas appliance. More exhaust does not fix blocked intake; it makes it worse.

• Baffles in every rafter bay with a vent beneath it.
• Intake area at the soffit roughly matching exhaust area at the ridge.
• Bath and kitchen fans ducted through the roof or wall, never into the attic.
• An air-sealed, insulated hatch — the largest single hole in most ceilings.

When this is the wrong answer

Powered attic fans are almost never the answer in Toronto. With insufficient soffit intake a powered fan pulls conditioned air out of the living space through ceiling leaks. Fix the intake and the passive system does the job on its own.

Common questions