This diploma thesis focuses on providing knowledge about the use of wood in the building industry, its protection against insects, fungi and protection against fire with various means of fire protection. The main goal of the thesis is the experimental comparison of values of weight reduction on samples of chipboard and spruce wood treated with a fire resistant coating in various concentrations by means of a radiant heat test. The first chapter consists of the general understanding of the use of wood and wooden products, the second chapter contains the goal of the thesis, which is the fire resistance evaluation of the chosen wood types treated with a fire resistant coating. The third chapter focuses on the description of the testing method, the testing equipment and the preparation of the samples. The last chapters are dedicated to the evaluation of measured data from the conducted experiment and to the discussion. After the experiment and evaluation of the data, we came to a conclusion that two layers of coating with all concentrations caused a drop in the average weight reduction of both chipboard samples and spruce wood samples. This difference is the most obvious in the spruce wood samples where the additional layer of coating caused the weight reduction to decrease almost double with all concentrations. Lowering the concentration of the fire retardant caused an increase in the weight reduction of the samples. Combustion times have increased with every layer of fire retardant coating on each sample of chipboard with all of the concentrations.