The article describes the basic features of the lightweight floor system with heat-dissipating lamellas (LFS-L) that do not require screeds and are used in the design of radiant heating. It was assumed that reactive polyurethane adhesive constitute the connection layer between the ceramic tile floor and the thermal insulation substrate, which is covered with aluminium foil. This type of construction has not been fully tested for mechanical strength. To define it, for example, using the finite element method, strength indicators of the tested adhesives which were not used in any of the previous studies discussed in this paper should be determined, such as Young's modulus E, Poisson's ratio ν and linear thermal expansion coefficient 𝛼. This article presents research methods by which these data were determined. Module E and the ν ratio were determined in the compression strength test of cylindrical samples of polyurethane adhesive. Coefficient 𝛼 was determined by using digital image correlation in the Aramis system, placing the prepared adhesive samples in a thermal chamber.
