Reinforced panel (1) for forming a roof covering and manufacturing process of this panel (1), according to which a continuous layer (6) of retardant or intumescent resin is spread on a surface (5) of at least one plate (2) of light-permeable plastic material; a reinforcing sheet (3) of light-permeable inorganic material is laid on the resin layer (6) before crosslinking the resin that fastens the reinforcing sheet (3) to the plate (2) of plastic material; the resin layer (6) and the reinforcing sheet (3) define a homogeneous layer (A') for holding parts of the plate (2) of plastic material when it reaches, even if only locally, its melting point.