Natural stone exchange material for buildings is in most cases selected only according to esthetic criteria. To avoid long-term damage the exchange material must be compatible with the existing natural stone material concerning the hygric and thermal properties. The water-accessible porosity, the capillarity and the drying velocity, the heat capacity, and the thermal and the temperature conductivity are the most decisive properties, according to which a suitable natural stone can be assessed for the use as an exchange material in an existing masonry.