The conducted studies of the impact of thermal action of a high-temperature magnesium flame on construction materials for timber protection from atmospheric factors revealed a pattern of temperature transfer to timber. It was proved that depending on the thermophysical properties of the material, this can lead to its ignition or slowing down the thermal conductivity process. That is why there arises the need to study the conditions for thermal conductivity and establish the mechanism for inhibition of heat transfer to timber. In this regard, a mathematical model of the process of transferring heat flow on the surface of timber when protected by coatings was developed. According to the experimental data and obtained dependences, it was established that the density of heat flow through a steel plate increases to a value of more than 200 kW/m2, which is sufficient for ignition of timber. Instead, the density of heat flow through a vermiculite plate did not exceed 5.2 kW/m2, which is not enough for its ignition. It was established that the main regulator of the heat transfer process is the heat-insulating properties of a construction product, its resistance to high temperature, because certain construction products, such as an asbestos-cement product, are destroyed under the influence of magnesium flame. That is why a significant impact on the process of protection of natural combustible material when applying the protective coating is made in the direction of heat insulation of the timber surface. This makes it possible to argue about the relevance of the detected mechanism of the formation of heat-insulating properties when it comes to the protection of storage sites of explosive products and the practical attractiveness of the proposed technological solutions. Thus, the features of inhibiting the process of transferring heat to timber during the action of the magnesium flame include heat insulation of timber surfaces by thermally resistant material. Thus, the temperature of a magnesium flame was created on the vermiculate surface, and it did not exceed 100 °C on the surface of the timber