on top of each other use is made of a connecting element or mechanism 30 as shown in fig3 in the embodiment shown the connecting mechanism 30 comprises a rod 31 which has one end provided with an enlarged portion 32 by means of which the connecting mechanism can rest against one of the shoulders 16 17 18 or 19 in the openings the enlarged portion 32 can constitute one unit with the rod but it might also be a separate unit which during the erection of the wall is provided each time to the end of the rod 31 the enlarged portion 32 is provided with means for accommodating the end of another rod 31 in such a way that the two rods are fixed to each other in the embodiment shown the enlarged portion 32 as seen in the axial direction of the rod is provided with a bore 33 which is provided with a thread and the rod 31 or at least the end portion thereof is provided with a thread of the same pitch the diameter of the thread of the bore 33 corresponding to the thread of the rod 31 the external surface of the enlarged portion 32 can have the shape of an hexagonal nut so that it fits to tools by means of which the rod 31 can be screwed on the length of the connecting mechanism 30 varies to accommodate a plurality of building elements in one embodiment as shown in fig3 the length of connecting mechanism 30 is basically equal to the height of the building element plus the length of the thread portions extending into the enlarged portion.