Exhaust Vent Roof Ducting in Toronto & the GTA

Crawl into a random GTA attic and there's a fair chance you'll find a bathroom fan hose ending in the middle of it, blowing shower steam onto cold sheathing all winter. The result is frost that rains down on mild days, wet insulation, and black mould creeping across the underside of the roof deck. The fan itself works fine — the ducting was just never finished.

Doing it right means a short, straight, insulated duct run from the fan to a dedicated roof cap with a backdraft damper. Uninsulated duct in a cold attic sweats and drips back through the fan — that mid-winter drip most people report as a roof leak. Dryer runs need smooth-wall duct and a screenless cap, since lint plus mesh equals a blockage. And every fan gets its own cap; ganging two bathrooms into one invites crossover.

We quote the full run — duct, insulation, roof cap, flashing, and removal of whatever the old arrangement was. Sometimes the honest answer is a wall exit instead of a roof penetration, and we'll say so when it's the better route. The Ontario Building Code wants exhaust terminated outdoors, not in the attic or at a soffit, and that's one code line entirely on your side.

• Insulated duct run from the fan housing to the roof, kept as short and straight as the framing allows
• Dedicated roof cap with backdraft damper, flashed into the shingles
• Smooth-wall, screenless setup for dryer vent roof terminations so lint can't nest
• Joints sealed with foil tape or clamps — cloth duct tape has no business in an attic
• Removal or capping of old ducts that dump into the attic or aim at a soffit
• One cap per fan — no ganged runs sharing a termination
• A look at the sheathing and insulation for mould or frost damage left by the old setup

• How many fans or appliances need runs to the roof
• Run length and routing — trusses, chimneys and tight attic clearance all slow the work
• Duct type: bathroom fan, grease-rated kitchen exhaust and dryer runs are each specced differently
• Roof pitch and height for the cap installation
• Condition of what's there now — a clean retrofit versus undoing years of improvisation
• Whether mould cleanup is needed after a long-running attic dump

Every home is different, so we don’t publish flat prices — the quote is free and based on your actual job.