PURPOSE: To prevent the peeling of a heat-insulating material and shorten the heat-insulation construction by laying the heat-insulating material on the whole surface of a slab through waterproof lime wash, fixing the heat-insulating material and covering the upper section of the heat-insulating material with covering mortar, in which fibers are mixed.

CONSTITUTION: The upper section of a slab 7 surface is covered with waterproof lime wash 4, in which adhesives for cement are mixed by an area corresponding to approximately one heat-insulating material, and separate heat-insulating material is laid successively on the waterproof lime wash and laid on the whole surface extending over the whole region of a slab 7. The heat-insulating materials are fixed by studs 1 mounted to the periphery and corner sections of the slab 7 through screws 2. The upper sections of the heat-insulating materials are covered with covering mortar 6, in which alkali treatment-resistant glass fibers are mixed.