Polyvinyl Chloride – Unplasticised. The rigid plastic used to manufacture Eurocell windows and doors. PVC-U provides low maintenance coupled with long life. The term PVC-U is often misunderstood. Mis-spellings include PVC, PVC-U, U-PVC, UPVC, PVCu and uPVC. PVC-U is sometimes also referred to as just plastic, e.g. plastic windows.