The purpose of the thesis was to study and model the foundations of buildings. In the study the aim was to model three different structural layers commonly used in the foundations of buildings. The modellings were done to study freezing, sealing and capillarity. First the study dealt with the basic investigations of foundations, then factors affecting the soil layers were discussed, which was followed by a closer research about soils and their properties. Then surveys and measurements of supporting soil layers were made. After that the results were studied. Finally, reflections and conclusions on the results of studies, their causes and effects were made.