In multi-storey large panel dwelling buildings, external walls were constructed from three layers: façade layer made from reinforced concrete, thermal insulation layer made from polystyrene or mineral wool and structural layer made from reinforced concrete. Connection between these three layers consisted of fasteners and pins made of steel bars. From the safety point of view, the most important structural elements in sandwich panels are steel hangers. The main defects observed in the external panels of existing buildings have been described as well as methods of improving the safety of connections between layers.