T & T Windows_uPVC Window,Door, Partition::.. Unplasticised Poly Vinyl Chloride has proved to be the most durable building material in use for over 40 years. uPVC is naturally not combustible and had been impact modified … Unplasticised Poly Vinyl Chloride has proved to be the most durable building material in use for over 40 years. uPVC is naturally not combustible and had been impact modified …