I want to insulate my old, hard-pipe, non-insulated air ducts. They are in the crawlspace. My options seem to be...
1. "Classic" fiberglass duct wrap. You wrap it around, tape it together, and try not to compress it too much. Yeah? Downside: Fiberglass is yucky to work with.
2. Bubble wrap insulation. Not yucky to work with, but you have to keep airspace between the duct and the bubble wrap by using spacers. It might be tricky to install properly.
Does anyone have preferences? I'm particularly interested to know whether anyone has installed bubble wrap insulation (with the airspace, obviously) and been successful. I know it's common for people to install the stuff improperly.
One other issue: My ductwork rests on concrete blocks on the floor of the crawlspace. I guess I'll need to insulate around those blocks as well since I can't actually insulate the part of the ductwork that's resting on those blocks?