This diploma thesis focuses on theoretical categorisation and brief characterisation of building constructions, especially focusing on wooden constructions and on characterisation of their chosen properties. The work also deals with the importance of fire protection of building materials, evaluative criteria and testing methods.The results of laboratory testing procedures are provided in practical part of the work. Two types of retardant substances applied on spruce wood were tested (FLAMGARD and PLAMOSTOP D transparent). The main goal of the experiment was to observe effectiveness of both substances during 2 and a half years. The results are continuously connected to the results of the bachelor thesis. Observing of the ageing effect was therefore possible. Assessing criteria were weight loss and ignition time of spruce wood. Stability of properties during lifespan of retardant substances and the influence of retardant protection on cross section and longitudinal section of fibres in spruce wood were among the assessing criteria as well. The experiments show stability of fireproof coating protection.