To provide a light semifinished panel having mechanical strength.

The method for obtaining the panel of laminar synthetic material used in the field of fixtures parts includes a process for preparing at least one coating sheet related to both of the opposed larger surfaces of an open mold having an inner contour fitted to the formation of a vertical panel or pretreated according to circumstances, a process for closing the mold, a process for filling the mold with polystyrene pearls until occupying at least the whole volume of the mold, a process for performing the cast molding of a preliminarily metered polyurethane resin having high fluidity in the mold corresponding to more points, a process for impregnating the polyurethane resin with polystyrene pearls to polymerize synthetic matter in the mold controlled to about 50°C and a process performing the opening of the mold and demolding a product of which the side surface is coated. The panel comprising the laminar synthetic material formed by this method is also disclosed.