Energy saving has become a significant concern in recent years due to increasing carbon emissions and environmental pollution. When examined from a global perspective, it is known that the energy consumed for heating and cooling of buildings is relatively high. In this regard, researchers attach great importance to energy efficiency issues. In recent years, an issue that has been given priority in heating buildings more efficiently is underfloor heating systems. Underfloor heating systems are composite structures of slab concrete, insulation material, hot water pipes, and screed. Here, the thermal performance of the screed is vital as the hot water pipes remain embedded in the screed. This study has produced a new composite and self-leveling screed type that can transfer heat easily. For this purpose, nine screed mixtures were prepared, including a reference (nearly conventional) screed mortar. The screed mortars’ flowability, density, and compressive strength were determined regarding physical properties. Thermal properties, thermal conductivity, specific heat, thermal diffusivity, and heat storage analyses were carried out. In the second stage of the study, a basic underfloor heating system was installed, and the temperatures of the water circulating in the system, the outer surface of the pipe carrying the water, and the outer surface of the screed were measured at specific periods. According to the study results, it has been observed that depending on the thermal properties of the screeds produced within the scope of this study, when used in underfloor heating systems, it can transfer heat from the hot water pipes to the surface with minimum losses.