Vent-Hood Ducting Need Insulation

This is a homeowner forum post, not yet answered, so there's no expert guidance to pass along. The homeowner is building a house and asking about the duct that carries air from their kitchen vent hood (the exhaust fan over the cooktop) out of the house. Their questions: does that duct need insulation, should it run through conditioned space (the heated and cooled part of the house) rather than an attic or other unconditioned area, and could it share space with the HVAC ducts inside the home's plenum trusses (roof trusses built with a gap to route ductwork)?

These are reasonable questions for anyone building or renovating a kitchen with venting range hood. An uninsulated duct running through unconditioned space, like an attic, can let outside air leak in or cause condensation when warm, moist kitchen air hits a cold duct wall. Routing the duct through conditioned space, or insulating it if it must pass through an unconditioned area, is a common way builders avoid that problem.

At the time of writing, no replies had been posted to this question, so there's no specific answer yet about whether insulation is required or whether sharing the plenum truss chase with HVAC ducting is a good idea. Homeowners planning a kitchen remodel or new build with a vented range hood face the same basic choices: where the duct runs, how it's sealed, and whether it needs wrapping to prevent moisture problems.