Input the mass of fixing screws based on the surface area of the product, expressed in g/m². By default, it is assumed to be 3.85 g/m² in standard areas. This value is derived from the quantity of screws per m² fixed at 1.1 screws/m², in accordance with the trade rules for cladding of 1981 – 2nd Edition - Chapter 4, based on a standard screw weighing 3.5 g.