The study examined 15 samples of basalt thermal insulation covered with foil. These materials are widely used in construction for thermal insulation and to increase fire resistance of building structures. The main objective was to identify non-combustible materials among the samples presented. Non-combustibility testing was carried out in accordance with the provisions of ISO 1182-80 “Fire tests. Building materials. Non-combustibility test”. Due to the layered structure of the materials under study, each layer (basalt fiber and foil with adhesive residues) was subjected to a separate study. The tests were carried out twice. The results of tests in a combustion chamber showed that 13 of the studied materials (87%) did not meet the non-combustibility criteria, and only two materials (13%) demonstrated compliance with fire safety requirements and can be used without any restrictions. To improve safety, an amendment should be made to the regulatory documentation, providing for the need to test multilayer materials for non-flammability not only by layers, but also as a whole. The combination of two non-flammable substances does not always guarantee the non-flammability of the final product.