The present invention concerns a columns assembly for an insulating wall of a building structure, said column having a side surfaces adapted to receive and retain insulation panels of the insulating wall, said column assembly comprising an inner spacer element made of mineral wool fibers, a central element made of mineral wool fibers, an outer spacer element made of mineral wool fibers, wherein the spacer elements are assembled with first and second intermediate profiles between the spacer elements, and wherein the density of the mineral wool in the central element is higher than the density in the inner and outer spacer elements. The invention also concerns an insulating wall assembly of a building structure with such a column assembly and a method of constructing such insulating wall.