Therefore, when installing the window, the workers are left to themselves, and the quality of their work due to the lack of control over the installation of metal -plastic structures often suffers. It is very seductive to put less fasteners or not foam, despite the fact that this goes unnoticed from time to time. The habit of dishonesty is developed, there is a lered to professionalism in the industry. All this goes on increasing, and the customer of plastic windows is not protected from marriage in such a situation.