This study was conducted to analyze the effects of the presence of rubble on soil porosity. Brick, con- crete, and aerated autoclaved concrete, 10% by weight, were added to soil samples. The changes in soil prop- erties were analyzed in the course of thermal stress – alternating the temperature of the soil samples between -20ºC and +30ºC. Humidity was kept at a constant 25%. The study was conducted on two groups of samples. Both groups consisted of soil mixed with building materials and one group contained an additional 6% by weight of peat as a reclamation factor. The measurement of the pore size distribution was performed on a mer- cury porosimetr AUTOPORE IV 9500, of MICROMRTRICS. In the course of the study it was demonstrated that the presence of building materials had a significant impact on soil porosity, and that the extent of this impact varied throughout the course of thermal stress.