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.
Water Managed Roof – Re-roofing and Adding Insulation Over a Sloped Roof Description Guide describing how to re-roof an existing home with a sloped and add insulation above the roof deck.