Seal off the chimney chase with sheet metal and or non combustible caulk.
Bathroom fan insulation attic.
Insulate your attic access door hatch with weatherstripping and foamboard to r10.
If you see that your duct isn t insulated at all pick up duct insulation at the home center.
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.
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.
To avoid mistakes not running it at all consider installing switches with built in timers.
While insulating you can make some mistakes.
Caulk foam seal all penetrations into the attic space ie duct chases plumbing chases wiring electrical boxes from lights down below.
Insulate the bathroom exhaust vent fan ducts.
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.
Options for venting a bathroom exhaust fan include best to worst.
You may find that the insulation simply needs to be refastened.
Bathroom exhaust fans perform an important function by removing excess moisture from your home.
Bathroom vent fan ductwork insulation.
The first step is to head to the attic.