Currently, authors develop methods of calculating the probability of escape from unique buildings by the probability of input parameters, namely, the specific rate of burnout, the linear velocity of propagation of the flame of fire load, the number of evacuated people, the rate of people during movement a fire, start of the evacuation. On the basis of a stochastic simulation model that implements the Monte Carlo simulator 'Town Planning Code of the Russian Federation of 29.12.2004 No. 190' was developed by assessing changes in the height of smoke-free zone during the development of a fire in the atrium. Comparison of simulation results with experimental data on the fire in the atrium of the model shows coincidence between calculated and experimental data. The aim of future work is the perfection of the presented model and increase of the number of the model input parameters.