Abstract: A novel vault for industrial furnaces, such as glass-making and metallurgical furnaces, comprised of a plurality of arches arranged side-by-side and each composed of a plurality of archstones made of fused cast refractory material. The archstones include a relatively thin slab-like lower portion and at least one upper rib integral therewith extending along the longitudinal direction of the individual arches. The corresponding ribs of the archstones of a given arch are aligned and define recessed portions filled with a refractory concrete having preferably good thermally insulating properties. A highly efficient thermally insulating structure covers the filled archstones.