Large doors have enough surface area to allow substantial heat loss by conduction. All types that have large panels can be insulated well, but this requires careful design by the manufacturer, or careful installation in the field. Effective insulation requires thickness, an unbroken surface area, and snug contact between the insulation and the door.Doors with many small segments cannot be insulated well. This applies to rolling doors and overhead segmented doors. Insulation can be placed
inside each segment, but the metal frames of segments comprise a large path for heat loss.