Bearing in mind a system construction and use, it is necessary to assess the thermal insulation material and effects on it. If a floor is thermally insulated above a basement with no heating, there should be a levelling concrete layer above the material; during the service time, the material could be exposed to significant mechanical loads and therefore one must chose polystyrene foam with elevated load tolerance (at least EPS 80). In cases when you thermally insulate a cover between a residential premise and attic with no thermal insulation, you can chose a material with lower load tolerance because the material will not be exposed to such a high mechanical stress. However, to prevent the flow of warm air through load-bearing structures in an upward faced direction, it is necessary to include a steam insulation layer. If the designed thermal insulation layer is not thicker than 100mm, it should be mounted in several layers, to avoid overlapping seams and creating cold bridges.