The present invention refers to a method for making a reflecting stratiform structure (100), configured so as to reflect the incident radiation coming from an upper side with respect to the reflecting stratiform structure (100), comprising an upper transparent protective coating layer (101) configured in that the upper transparent protective coating layer (101) is applied to the reflecting stratiform structure (100) through a cross-linking process, which is carried out by cross-linking a polymerisable resin, which will form the upper transparent protective coating layer (101), making energy pass through a transparent thermoplastic film (102, 120), preferably made of polyethylene terephthalate (PET), so as to cross-link the polymerisable resin.