wall insulation on the exterior side

Most wood-framed buildings have no insulation on the exterior side of the wall sheathing. Material, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. That means that the wall sheathing gets cold and wet during the winter.