I just bought a house and am evaluating my options for A/C retrofit. We have a partially finished attic, and plan to fully finish it. The roof is currently uninsulated. We have 6" roof joists.
One installer I spoke to proposed to put down 2" of closed-cell foam along the roof deck, then to run oval ducts between the joists in this partially insulated space, and then finally to envelop the ducts in additional spray foam.
Vanguard Energy expressed horror at an analogous setup that used fiberglass batt. The installer argues that this setup is much better than that because the spray foam insulation performs so much better.
Is he right?