What is the price to install bathroom exhaust ductwork through a Toronto home roof?

Installing bathroom exhaust ductwork through the roof of a Toronto home typically costs $500 to $1,200, including the exhaust fan, insulated duct, roof cap, and all connections. If you are replacing an existing fan and duct, the cost drops to $300 to $700 since the roof penetration already exists. This is a project that directly protects your home from moisture damage, and doing it correctly is critical in Toronto's climate.

The components of the installation include the exhaust fan itself ($80 to $300 depending on CFM rating, noise level, and features like humidity sensors or motion activation), rigid or semi-rigid duct ($3 to $8 per linear foot), R-8 insulation wrap for the duct ($1.50 to $3.00 per square foot), a weatherproof roof cap with damper ($30 to $80), and professional installation labour at $75 to $120 per hour. The entire installation typically takes three to five hours for a professional, longer if attic access is difficult or the bathroom is on a lower floor of a multi-storey home.

The Ontario Building Code requires bathroom exhaust fans to deliver a minimum of 50 CFM and terminate outside the building envelope. Venting into the attic or soffit is a code violation and one of the most damaging mistakes found in GTA homes. Warm, humid bathroom air vented into a cold attic during a Toronto winter creates massive condensation on the underside of the roof sheathing, leading to mould growth, wood rot, and eventually structural damage. Every year, Toronto home inspectors flag this issue in hundreds of homes — if your bathroom fan currently vents into the attic, getting it properly ducted to the roof or an exterior wall should be a priority.

Insulating the exhaust duct in the attic is non-negotiable in the GTA. Warm, moist exhaust air travelling through an uninsulated duct in a minus 20 degree Celsius attic condenses immediately, and that water runs back down the duct into the fan housing, dripping onto the bathroom ceiling and creating water stains and mould. R-8 insulation wrap with a sealed vapour barrier prevents this condensation. The duct should slope slightly upward toward the roof cap so any residual condensation drains outward rather than back into the home.

Rigid metal duct is preferred over flex duct for roof-terminated bathroom exhaust. Flex duct sags between supports in the attic, creating low spots where condensation pools, and its corrugated interior collects lint and dust that reduces airflow over time. If flex duct is used, it must be pulled taut and supported every four feet — but rigid 4-inch or 6-inch round duct with proper fittings is the better long-term choice. The electrical connection for the exhaust fan must be done by an ESA-Licensed Electrical Contractor in Ontario. Need help finding a contractor? Toronto Ductwork can match you with local professionals through the Toronto Construction Network.