Aim of the work presented in article is study of the effects of long-term working lifespan on the fire hazard of wooden structures with the assessment of temperature characteristics, measures of process of burning and charring of designs in standard temperature conditions of a fire in accordance with GOST 30403-2012. Carried out researches have allowed to establish features of the behavior in fire conditions and fire hazard of wooden structures of long term operation on the example of enclosing structures of uninhabited wooden object. According to the study it’s determined a significant influence of the long working lifespan of wooden structures on the rate of thermal burn-in sample, the values of speed of charring (the charring rate in combustion chamber is increased in 1.7 times), and heating intensity on the thickness of the sample. This suggests that long-term natural aging of wooden structures leads to facilitate the carbonization of the wood and accelerate the oxidation process of decarbonized balance. Special attention was paid to the temperature in the firing and thermal chambers test installation for testing samples of designs. In the experiment it was discovered that the fire activity for 45 minutes per sample of wooden structures with life of 81 years, throughout the experiment the temperature was actually more at 50 °C compared to a model of modern wooden structures in temperature test and combustion chambers. This may lead to a deterioration of the fire hazard and the environment, including improving the thermal regime and toxicological hazards in buildings and structures. Identified features needed during developing methods to reduce the fire hazard of wooden structures with long-life performance, including the development and application of fireproofing materials, selection of substances and compounds that reduce the intensity of the dissipation influence on the structure and oxidation capacity of the coal layer, as well as the intensity of the process of coal formation.