uPVC, which stands for unplasticised polyvinyl chloride, is a type of rigid plastic that is often used within doors. In fact, we have doors almost entirely made up of this one material. However, in composite doors, the uPVC is used for the inner layer to take advantage of the great qualities this material offers.  The properties of this material are the following:  Durability – Whilst GRP resists chemicals and corrosion, uPVC not only increases this defence but also adds to it by also resisting rot. Overall, these combined defences increase the door’s lifespan.  Thermally Efficient – uPVC has a very low level of thermal conductivity. This means that it doesn’t allow heat to transfer through the material easily, meaning that heat is more efficiently trapped within the home. This way, eventually, the door will end up paying for itself in how much you’ll save in energy. This is particularly important in the cold Scotland weather.  Weather Resistance – uPVC aids in GRP’s ability to stave off the warping that comes from weathering.