This ducting had been insulated and re-insulated three times before we got to it; the problem was the ducting was on a side of the building that experience extreme weather conditions i.e. lots of wind and sun. Conventional systems (fiberglass) could not hold up to these conditions. We installed 2” inches of 2 lb. spray foam and coated the foam with 2 gallons per square of Acrylic Coating. Problem solved and the customer says the system is running more efficiently.