Abstract
Frost damage occurs especially if damp building elements are subjected to frequent freeze-thaw cycles. The observation that frost damage can also be frequently observed in warmer winters - for example in the winter of 98/99 confirms that one cannot use the outside air temperature level as the only criterion, but that the combination of the number of freeze-thaw cycles in the building element's interior and the moisture content in the material at those times must also be considered. The number of zero crossings on a Celsius scale during each half year of the winter, and the corresponding moisture content profiles were calculated using the PC program WUFI for the example of a calcium silica brick wall construction. The effect of different meteorological conditions on zero crossings and material moisture has been determined using meteorological data measured during several years at the Fraunhofer-Institute for Building Physics (IBP) outdoor testing field. From the results, it is possible to assess the frost damage risk.