The first step is to head to the attic.
Bathroom fan insulation attic.
To avoid mistakes not running it at all consider installing switches with built in timers.
Before you rush to the attic or go the roof to check for any leaks make sure the exhaust fan duct is properly insulated and run the fan more frequently for a prolonged period.
While insulating you can make some mistakes.
Seal off the chimney chase with sheet metal and or non combustible caulk.
If you see that your duct isn t insulated at all pick up duct insulation at the home center.
Bathroom vent fan ductwork insulation.
If bath fan ducting isn t properly insulated the moist air from your house will condense inside the duct.
In un conditioned space such as an attic where otherwise your fan duct will be exposed to cold attic air in winter use insulated solid metal ducting or insulated flex duct.
Insulate the bathroom exhaust vent fan ducts.
The building code requires a bathroom exhaust fan to vent outside the building so installation of a new bathroom fan necessarily involves installation of ductwork.
Options for venting a bathroom exhaust fan include best to worst.
Bathroom exhaust fans perform an important function by removing excess moisture from your home.
Insulate your attic access door hatch with weatherstripping and foamboard to r10.
This is much easier to do if you have attic access because if you don t you usually have to remove some ceiling drywall and run the ducts along a joist.