Otherwise the exhaust duct gets too cold when it runs through the attic.
Exhaust vent pipes in attic should be insulated and vented.
It really is a design choice.
Intake vents located at the lowest part of the roof under the eaves allow cool air to enter the attic.
Your attic is not a temperature controlled environment is never the same temperature as your living space and generally closer to the temperature outside.
Insulating around a furnace exhaust pipe.
If the insulation around your vent hood duct work becomes waterlogged because of a roof leak or similar problem the insulation s effectiveness will be compromised.
The best exhaust fan venting is through smooth rigid ducts with taped joints and screwed to a special vent hood.
If this pipe is not insulated the heat carried in the air transferred to the pipe will cause condensation and potentially cause water damage at your ceiling or in your attic.
Now that you have safely sealed the air leaks around the furnace exhaust you can work on insulating your attic space.
Although this isn t always possible in attic crawl spaces you should always insulate the duct to prevent condensation problems.
However since the 2009 edition of the irc attics can be designed to be either vented or unvented.
So the decision to vent an attic space is not dictated by building code.
Although fiberglass may not burn it can melt contribute to a fire and the speed at which it spreads.
Ventilating attic spaces is often viewed as a technical requirement for steep slope roof assemblies as well as a building code requirement.
We insulate the bath vent ductwork to minimize the condensation that will otherwise occur as warm moist bathroom exhaust air passes through cool ductwork in the building attic or roof cavity.
Of course all penetrations where drainage or vent pipe goes through walls especially into attic should be sealed around the pipe to prevent infiltration.
Our photo above shows a long routing of bath vent fan ducts across an attic floor to an exit at the building soffit or eaves and the condensation of moisture in such vent lines.
A cold duct allows condensation of moist indoor air leading to drips from the exhaust fan.
The solution properly insulate the vent ducts.
The reason exhaust pipes are insulated in unconditioned spaces your attic is because they carry warm and moist air from your home to outside.
You should never exhaust the bathroom fan directly into the attic.
Horizontal runs are covered with insulation bats in the attic usually.
Hot air exhaust vents located at the peak of the roof allow hot air to escape.
Does bathroom vent piping need to be insulated.
No you cannot vent your bathroom exhaust fan into the attic.
Just as is the case with insulation in other parts of your home you should regularly inspect and maintain the insulation on your duct work.
In our neck of the woods vermont it is required by code to protect the vent stack from freezing.
