In the area of ​​several cities in Poland, and, inter alia, in Bydgoszcz, Jarosław, Kłodzko, Sandomierz, there are specific ground conditions, which cause serious damage. Lots of buildings are breaking down, the scratches and cracks divide their body vertically into several segments. Damage to buildings is in most cases serious and puts public safety at risk. In some cases, the course of scratches and cracks in the walls, vaults and other elements, it is irregular, in others, the scratches and cracks are concentrated in specific parts of the building, widen upwards; in a number of cases it is found, that the load-bearing walls swing outwards from the vertical. Detailed building damage studies, including, of course, the historic ones, led to the finding, that their damage occurs as a result of deformations caused by periodic movements of the substrate. The danger of these phenomena is all the more dangerous, that they are hidden and occur unexpectedly, despite the fact that the soil apparently has good mechanical properties. The soils that cause these unpleasant surprises include loams and loess.

Clays and loess have very diverse and specific properties. The loams are soils of alluvial origin (sedentary). They are characterized by the smallest particle size composition. The mechanical properties of loams depend very much on their moisture content. In the plastic state, the strength of the clay is negligible. Lessa, in turn, belong to the finest-grained deposits of aeolian origin (wound). Loess plasticity increases rapidly due to moisture and hydration. They are permeable soils, water-absorbing and water-absorbing. Their plastic strength is minimal. Both types of land, when they are wet, under load significantly deform. As a foundation, they can only work under appropriate conditions.

Based on research and observation, it can be concluded, that they have an impact on changes in bearing capacity of these lands: Seasons, climatic fluctuation, intermolecular imbalance due to moisture migration and vegetation of some species of vegetation and others.