Heat-insulation building block of all-metal construction

Heat-insulation building block formed of at least two parts slideable relative to one another over a given range and, respectively, including between two metal housing sheets maintained at a constant spacing from one another, a multiplicity of metallic insulation foils disposed consecutively in direction of said spacing between said housing sheets, and spacer elements holding the insulation foils in spaced relationship to one aother, adjacent pairs of the consecutive insulation foils forming respective insulation cells, the housing sheets and the insulation foils of the respective parts being nested overlappingly within one another in consecutive alternating fashion within the given sliding range, the housing sheets and the insulation foils of the slideable parts nested within one another having respective overlap lengths greater than a maximum enlargement of the building block resulting from sliding the parts of the building block apart in direction of the given sliding range, comprising bent-away portions formed at a free end of the insulation foils of at least one of the relatively slideable building-block parts, said bent-away portions bridging the space between respective pairs of the consecutive insulation foils and tightly engaging elastically respective adjacent insulation foils of at least the other of the relatively slideable building-block parts, and hair-pin shaped bent-away portions formed as pockets engaging in one another at free ends of the housing sheets of the two building-block parts forming the building block.