The present invention relates to an improved waterproofing panel, comprising a plurality of sections with a predominantly flat and polygonal geometry, and said sections being enabled to be arranged and fitted one after the other in an extension of their own flat geometry; wherein each section is made up of a rigid and flat core of the same polygonal geometry as the section itself and a waterproofing sheet superimposed on the core and joined to one another, wherein the sheet is covering the core and said sheet has projections that extend and protrude from the core on two contiguous sides of the same core; so that in the arrangement of the sections one after the other, the projections of the sheet of one section are superimposed on the other adjacent section.