Input the mass of the fixing screws based on the surface area of the product, expressed in g/m². By default, it is assumed to be 3.5 g/m² in standard areas. This value is derived from the quantity of screws per m² fixed at 1 screw/m², in accordance with NF P 34-205-1 DTU 40.35 – Edition of May 1997 –“Roofing with profiled sheeting made of coated steel sheet”, based on a standard screw weighing 3.5 g.