The behavior of the building structures in case of the fire have many directions for study. The purpose of the research was to create a process of fire impact on the building constructions. In the theoretical part of the study, the main issue was to create method for numerical modeling for standard fire.This study was carried out in transient thermal processor for ANSYS and compared with real fire impact results.The study showed correlation of research data. The results can be applied to solve difficult goals of fireproof for spatial constructions and have use in practice.