Abstract: A floor which comprises a plurality of structural elements (10) of elongated parallelepiped shape with their longitudinal axis disposed horizontally. The structural elements are disposed adjacent to each other to form a flat horizontal structure supported by two opposing vertical walls (23) and 24) of the kiln. Each structural element (10) comprises two internal beams (11) positioned to the axis of the element and a plurality of blocks (12) of thermally insulating material, each being provided with two through holes (13) by which they are mounted along the internal beams (11). The blocks (12) are slidable along the internal beams (11); means also being provided for acting on the ends of the row of said blocks (12) to compress the row in an axial direction, thereby pressing the blocks together. The internal beams (11) are stressed only partially by the weight of the blocks (12), which can therefore have a greater specific gravity or thickness to increase the insulating effect of the floor.