Best way to insulate sweaty sheet metal ducts in unconditioned space?
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With foil and fiberglass duct wrap you have to use tape, and be able to get all the way around or it won't stay there (the tape has to lap over its other end or it will not hold).

I'd recommend self-adhesive foil and foam duct wrap.

You might want to do the easy-to-reach and the majority of it with fiberglass, and use the self adhesive where you have to, to keep the cost down.

Surface prep is to wipe with alcohol - do not use mineral spirits. And of course; to be dry.