Many owners of country houses meet with such a problem as mold. The mold itself cannot appear, and especially on dry and clean walls. It appears when temperature drops and, if the walls are not well insulated enough, then mold occurs in them. You can of course warm the walls with polystyrene, but this is not enough, and mold will again make itself felt. First you should figure out where the mold comes from where. There are three ways to get molds of mold. The building material from which the house was built, whether it is a brick, concrete or stone.