Mineral wool or polystyrene is most often selected as a heater material. Among the builders there are eternal disputes, which of these materials is better. Foam is cheaper material. At the same time, thermal insulation characteristics and both materials are approximately the same. But their vapor permeability is radically different. Mineral wool is a material that does not interfere with aerated concrete walls to «breathe». But with polystyrene, the situation is different — it almost does not pass steam. Thus, it is better to pay a little more by acquiring mineral wool.