To do this, reduce the level of humidity in the room and provide the proper level of ventilation. You also need to pay attention to the insulation, since freezing the wall will cause moisture condensation. But not only the absence of insulation can be the reason — cheap insulation helps no worse the fungus to appear in the house. Knowing the root of the cause of mold, you can begin an active struggle. The most common way for destruction is antiseptic primer. It destroys the fungus and does not allow its reappearance.