Replace restroom vent fans with quiet continuously operating fans. Prevalent on first floor. Excessive condensate drainage. Full time exhaust-only ventilation system is drawing outside air into wall assemblies and into the rooms. Vinyl wallpaper is trapping moisture inside walls, causing peeling and wall damage.
Major recommendations Install a supply-only ventilation system with dehumidification.
Replace vinyl wallpaper with non-vapor barrier paper. Institute maintenance routine to keep condensate lines open. Excessive humidity in summer. Numerous compressor failures. Findings Return plenum connected to outdoors.