In his latest newsletter, Joe Lstiburek provides an in-depth look at the various ways we as an industry have tackled the problem of cooling ducts sweating in the summer when they are run through attic spaces and other place outside the thermal envelope. In his inimitable practical style, he looks at what's worked and what hasn't - noting that "works" can apply both to performance as well as cost and convenience.
Here's an excerpt from one of the "solutions" he tackles:
It is not easy to move the “inside” to the roof deck. Actually, it is easy. But it is expensive and that makes it not easy. Let me explain. Spray polyurethane foam makes it easy from a technology, performance and installation perspective. But it is more expensive than going to dropped ceilings.4How about insulating above the roof deck with rigid insulation? See expensive and add the words “not easy” and “might look like #@%.