The first objective of the research was to determine the thermal and moisture conditions around slab-on-ground structures and to define the related boundary conditions for design purposes. The second objective was to examine the general moisture behaviour of typical slab-on-ground structures in changing climatic and indoor conditions throughout their life-span. The moisture-related parameters and behaviour of typical fill materials – capillary (vertical, horizontal) and hygroscopic moisture equilibrium – were determined. The thermal behaviour of the subsoil under a heated building was also determined by long-term in-situ tests and numerical modelling.