Particle board is widely used in building industry (bars, floor and wall coverings, etc.) as it is in furniture industry. Due to the relatively low thermal conductivity it can also be used to improve the properties of the wall insulation. In doing so, we must watch what the density of the selected panel is. The density of the layer that can be changed by the share of the middle layer, has the main impact on the thermal insulation. We wanted to determine the influence on an individual layer of the particle board on its thermal insulation. We designed 3 particle boards with different shares of the middle layer. In 1st case the share was 30 %, in 2nd 45 % and in 3rd 60 %. We placed the particle boards on a hot plate. The temperature of the enviroment and the hot plate in 1st case deviated for 15 °C, in 2nd 25 °C and in 3rd 35 °C. The highest temperature change between the middle layer and the upper surface had a board with a 30 % share of the middle layer and the hot plate temperature of 60 °C, the lowest temperature change had a board with a 30 % share of the middle layer and the hot plate temperature of 40 °C.