The master thesis is focused on the current issue related to thermal insulation of buildings. The master thesis is divided into two parts: theoretical and practical. The theoretical part deals with the analysis of issues related to building materials and their importance for the construction industry. Attention is focused mainly on those building materials that are part of the structural solutions of building envelopes. Since the work is thematically focused on the field of thermal insulation, part of the theoretical analysis is devoted to thermal insulation material (distribution, properties, use) and thermal insulation system.The practical part of the work is also oriented in the mentioned direction. It focused on the experimental evaluation of thermal resistance of materials used in the proposed thermal insulation system, especially thermal insulation materials. In first case, it is an evaluation of thermal insulation created of EPS (expanded polystyrene) board, at second case there is a combinate TWINNER insulating material (a combination of EPS and a layer of basalt fibers). in both cases of thermal resistance evaluation, a radiation panel was used as a heat source, temperatures in individual layers of the system were sensed by thermocouples, and the behaviour of the tested materials was visually monitored. The results of the evaluation showed that the TWINNER rest specimen withstood the ceramic radiation panel better than the Greywall test specimen. The TWINNER test specimen, using a fire basalt board, retained more of the EPS thermal insulation material than the Greywall test specimen.