A window or door unit is disclosed having means for equalizing air pressure within a window or door sash about the perimeter and front portion of the sash with atmospheric air pressure at the exterior of the sash under high wind conditions to avoid drawing up and accumulation of water within the sash. The structure of the invention comprises the provision of at least one vent opening in the upper portion of the sash on the exterior side of the sash for communication of exterior air with the interior of the sash and equalization of air pressure about the perimeter of the interior of the sash, in communication with at least one exterior water drain hole at the bottom of the sash, with exterior atmospheric air pressure.