With the ever-increasing demand for efficiency in new buildings, as well as the retrofitting of existing facilities, exterior sheathing plays an integral role in reducing energy consumption and the associated carbon dioxide (CO2) emissions. (This article deals with insulating, not structural, sheathing). Exterior insulation, continuous across all structural members without thermal bridges (other than fasteners and service openings), is the most thermally effective way to insulate a building. The sheathing’s thickness depends on the climate zone.