In the framework of the prefabricated panel, each node 78, 89 of a beam of even pair 6.4 couples the adjacent ends of two struts 57 and 68, 67 and 58 which extend respectively from the two sides of the beam in question and in the same direction, the directions reversing for the struts of the two consecutive beams of even pair (6.4 and 6.4); each node 59, 69 of a beam of odd row (6.4) couples the adjacent ends of two struts 57 and 58, 67 and 68 which extend respectively from the two sides of the beam in question and in opposite directions, the directions reversing for the equivalent struts of two consecutive beams of odd row (6.4 and 6.4).