A heat resistant electrical insulating unit having a rigid body of a ceramic material and a layer of ceramic fiber web bound to the ceramic body into a single unit. The unit may have several layers of rigid ceramic and fiber web layers with the fiber web layers spaced from each other and having an electrical resistance element interposed between them, the outermost rigid bodies being joined together mechanically or being welded together in such a manner that the fiber web layers and the interposed resistance element are held clamped between the rigid ceramic bodies. A method is also disclosed for making heating elements wherein a resistance heating element and the insulating layer or layers are joined together into an essentially two-dimensional unit and are placed on a flat glass ceram body which has been heated to a welding temperature, and thereafter a second glass ceram body which has been heated up to body temperature is placed upon and pressed against the first-mentioned body in such a manner that the two bodies are welded together and enclose at least the edge portion of the said unit all around the same.