Facilities and limits of the quantitative characterization of the durability of porous sedimentary stone exposed to urban atmosphere are highlighted. A reference point for simulation of corresponding processes is lacking. Instead of this an orientation at a general approach for weathering behavior is necessary, which one may draw near experimentally. This would be possible by means of such methods the results of which take account of the essential weathering factors and are independent of geometry and position of the stone on the facade of the building. In this connection and besides the well-known saturation coefficient, one can first of all employ a new kind of characteristic value for the mass loss during the sodium sulphate crystallization test. In addition, some material properties regarding pore space, mechanical properties as well as their combinations seem to be useful for such an attempt. Preliminary results encourage one to continue along the taken route in order to create finally an objective basis for estimating the relative weathering resistance of the different types of stone.