I am finishing my basement and will have to put the main trunk(s) of my HVAC system in a soffit. I would like to insulate the duct work both for energy efficiency and to try to keep some of the noise from the basement from traveling up the ductwork to the upstairs. Do I need to use special insulation? Can I use regular unfaced fiberglass insulation or does it have to be foil faced? If foil faced, does the foil facing need to be flame-resistant FSK?
Iíve seen the usual R-6 foil faced fiberglass stuff at the big box stores but it seems overpriced and Iíd prefer more sound control than that little blanket will likely give me. I really canít find any good resources on the subject. Any help/advice would be greatly appreciated! Thanks!