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.
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.
Unvented Conditioned Attic with Spray Foam Insulation Below Roof Deck Description Guide describing a method for insulating an unvented attic by spraying foam insulation along the underside of the roof deck.