Checking the compliance of fire resistance of building structures in premises of various functional purposes with fire safety requirements is one of the most urgent tasks of the State fire service. The existing calculation methods use empirical dependencies for approximate assessment of fire resistance of a building structure. The article describes the method developed by the authors for operational verification of compliance of design solutions of building structures with fire safety requirements. The authors use numerical methods of solving the problems of non-stationary heat conduction to determine the heating of enclosing and load-bearing structures under fire impact. The author's computer complex with automated input of reference information provides the efficiency of checking the compliance of fire resistance of building structures with the normative requirements. The computational complex is developed in Microsoft Office Excel environment with the use of Visual Basic for Applications. Modules of the computational complex with automated input of reference information allow not only to carry out numerical modeling of fire impact on each element of building structures, but also to assess the compliance of its actual fire resistance limit with fire safety requirements. The application of the computational complex allows at the stage of making design decisions to identify and promptly carry out the replacement of elements, which have revealed non-compliance of the actual fire resistance limits to the established standards (in relation to the conditions of internal fire in buildings). In this case, the efficiency is evaluated and the necessary thickness of fireproof coatings is calculated, for which empirically established regularities of changes in thermophysical properties in the non-stationary mode of fire exposure. No special training is required for program implementation of algorithms of complex fire engineering calculations.