Does bathroom vent+range hood vent need insulated?
Vent pipes running through any unheated space should be sealed at any joints and insulated along their entire length. This reduces the chances of condensation created when a warm duct contacts cold air. If that joist space is between two heated floors and does not have access to cold air, you might be able to forgo the insulation. They key is to keep the exhaust air as warm as possible until it exits the building.
