Option is the

Type of electric warm floor, which is installed in a layer of tile floor

There are rooms where the use of screed is simply not permissible. Therefore, an alternative option is the installation of a warm floor in a layer of tile glue. Only instead of heating cables a special mat is laid, which is also heated. Then, after laying it, a layer of adhesive solution and mastic is applied. Unlike the screed, the floor rises not by 5-10 cm, but by several millimeters. After the glue solution is applied, the tile is laid.