Why Your Bathroom Exhaust Fan Isn't Actually Venting Outside

If you run your bathroom exhaust fan and the mirror still fogs, the room still feels damp well after your shower, or the fan is loud but doesn't seem to do much, the fan itself usually isn't the problem. The wiring, and more often the ductwork behind it, is.

The Duct Might Not Actually Go Outside

One of the most common issues we find on a service call is a duct that was never properly connected to an exterior vent cap at all. Instead of pushing humid air outside, it's blowing into the attic space, where it condenses on the underside of the roof deck and leads to mould and wood rot that isn't visible until it's already a real problem. This is especially common in homes where a fan was added after the original build, or where the vent run was left disconnected during a renovation.

The Fan Might Just Be Undersized

Builder-grade bathroom fans are often sized to the bare minimum for the room, which is fine for clearing light steam but not enough to keep up with a longer shower or a smaller, poorly ventilated bathroom. Fan capacity is measured in CFM, and sizing it correctly to the room, not just swapping in whatever unit is cheapest, is the difference between a fan that actually clears the air and one that just makes noise.

Wiring Can Limit What Fan You Can Upgrade To

A lot of bathroom fans are wired on a shared switch leg with the room's lighting, which works fine for a basic fan but becomes a problem the moment you want a humidity-sensing or timer-controlled unit that needs to keep running after you've turned the lights off and left the room. Upgrading to that kind of fan usually means wiring it to its own switch or sensor control, not just swapping the fan housing.

Get It Installed, and Vented, Right

We install and wire new bathroom, kitchen, and range hood exhaust fans, and fix existing ones that are underpowered or improperly vented, for homes and businesses across Toronto and the GTA. That includes routing ductwork to a proper exterior vent cap and wiring the fan to its own switch or humidity sensor where needed. Contact us or call us directly if your bathroom fan isn't clearing steam the way it should.