Image Right - Closed-cell spray foam covers the ceiling and joists to insulate and air-seal the ceiling deck.
Blown Insulation for Existing Vented Attic Description Guide describing how to insulate a vented attic in an existing home using blown insulation added to the attic floor.
Batt Insulation for Existing Vented Attics Description Guide describing how to increase insulation in existing homes by installing batt insulation on the ceiling plane of a vented attic.