In this section, ready-made products that are integrated into the overall structure during construction and renovation are presented. These include windows, doors, suspended ceilings, partitions, ready-made stairs, and similar elements. Typically, replacing windows, doors, stairs, and other integrated elements requires demolition work, followed by the restoration of the building or room&single_quot;s structural integrity and finishing work. Usually, windows, doors, ceilings, partitions, and stairs are installed for a long period and, therefore, require careful selection taking into account their technical and aesthetic characteristics.