There is an opinion that insulating an apartment from the inside, the problem of freezing the wall is solved. This is a huge misconception, because the freezing of the wall is not only a cold in the apartment, but also the presence of a “dew point” in your home.
“Dew point” – a place where cold, colliding with heat, forms a condensate.
If the thermal conductivity of the facade is increased, then the “dew point” is in the apartment and, as a consequence, the cold, high humidity, and fungus formation on the surface of the walls and ceilings.
To correct the situation, it is necessary to lower the overall thermal conductivity of the wall so that the “dew point” is outside your wall. The optimal solution is external insulation.
When the insulation of the problem area of the wall is only from the inside, you leave the “dew point” in your apartment. It creates the false impression that the problem is solved. In fact, you further aggravate the situation by creating greenhouse conditions, and by your own hands provide favorable conditions for the development of mold. Fungus, with even greater intensity than before warming from the inside, begins to spread not only on the surface, but also penetrates deep inside the wall and when you realize that you need to do something, the situation will go so far that you will have to try very hard to have it to correct.
Fungus, reproducing, secretes toxins (which can be both liquid and volatile) and spores. All this is easily carried through the air, throughout the room and, penetrating the respiratory tract into the human body, causes him irreparable harm. Especially vulnerable are children, elderly people, with weakened immunity and chronic diseases.
From the inside, of course, it is possible to be insulated, but only in addition to the external insulation. In the overwhelming majority of cases, people refuse this idea, immediately after the effect of insulation from the outside becomes visible, because the insulation from the inside has one more (by the way, everything else) minus – it “takes away” from your premises about 7 centimeters of useful area on the side where you put the same heater.