Koemmerling uPVC window and door systems have been successfully used in coastal and tropical environments without any detriment to the surface finish or performance. One of the main assets of Koemmerling window and door systems is their resistance to driving rain and their joint tightness. Koemmerling uPVC profiles fulfil the demands of EN 12208 (Resistance to driving rain). All window types are designed to be watertight when tested up to 300 PA as specified in BS 6375: Performance of Windows Part 1, 1989 : Classification for weather tightness. Some types achieve a 600 PA rating.