Buildings must not just preserve the appearance and architecture. Besides optical demands our homes have to meet the requirements on the room climate and its associated level of comfort. A major contribution is made by the "outer shell" - protecting everything indoors from temperature or moisture. Particularly uncontrolled external moisture can not only disturb seriously the durability but also the room climate of a building. KEIM impregnations and water-repellent agents make a key contribution far beyond aesthetic demands.