Abstract: A wall structure for vessels, tanks, washing towers, tubes, boat hulls and the like can be manufactured from elements consisting of a core of rigid plastic foam which on a first side is coated with a layer of non-expanded plastic which adheres to the core and preferably is of the same type as the latter, whereas the core is exposed on the opposite side. The elements have an elongated plank-like shape with opposite side surfaces having respective groove-and tongue-like design for matching mutual engagement. They can be rigidly engaged in side-by-side relationship by welding and/or gluing. On an exposed face of the assembled elements, a reinforced plastic mass which sets into a continuous layer is applied, if desired after grinding for evening out irregularities.