An exterior insulation panel for installation in an exterior building envelope of a building. The insulation panel has an interior face for facing toward an interior space of the building, an exterior face lying opposite the interior face for facing away from the interior space of the building, and a foam core laminated with a perforated exterior facer on one or both faces of the panel, at which the exterior facer defines an uncovered outermost layer of the panel. Each perforated facer comprises openings therein through which moisture is migratable into the foam core during moisture-rich environmental conditions, for temporary holding of the excess moisture until such conditions subside.