Always cover the tops of the ceiling joists to make sure the insulation is deep enough to reach your target r value and to prevent thermal bridging the heat loss that occurs through the wood framing.
Attic insulation over bathroom fan.
If you see that your duct isn t insulated at all pick up duct insulation at the home center.
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.
Work from the perimeter of the attic toward the door or hatch so that you don t trample all over the insulation you just put in.
The first step is to head to the attic.
Another approach could be an insulated hvac duct approach.
If bath fan ducting isn t properly insulated the moist air from your house will condense inside the duct.
There are several options available for the ducting like flexible aluminum ducting.
The box can be made from rigid foam.
Insulate the bathroom exhaust vent fan ducts.
I had insulation from 1952 that was less than an inch thick.
The seams can be taped with housewrap tape.
The exhaust fan housing should be covered with an insulated airtight box.
I want to make sure that is ok.
When venting a bathroom exhaust fan make sure to vent the air to the outside rather than into your attic where it can cause mold and mildew to form.
Caulk or spray foam can be used to seal the box to the ceiling drywall and to seal around the exhaust pipe.
But some consider it somewhat flimsy and may not support the weight of insulation over any distance.
You may find that the insulation simply needs to be refastened.
How well the insulation around the bath fan will work depends on the ducting greatly.
I just added r19 unfaced insulation to my attic.