Below Deck Spray Foam Insulation for Existing Roofs Description Guide describing how to add spray foam insulation to the underside of the existing roof deck as part of the conversion of a vented attic to an unvented, insulated attic.
Ducts Buried in Attic Insulation and Encapsulated Description This guide describes approaches to buryng and encapsulating ducts in unconditioned attics to increase the overall R-value of duct insulation.