During choosing a specific type of steel structures, the selection of the type of structure is usually made primarily according to the criterion of the weight of the structure, for the basic loads (permanent load, snow load, load wind...). In the majority of cases, the protection of the structure against the effects of fire is carried out by passive systems for the protection of the structure (coatings, cladding...). By choosing the type of structures more carefully already in the conceptual design phase, taking into account fire action, it is possible to obtain ultimately more optimal structures (not only from the costs aspect, but also from the aspect of use). Through the calculation of fire resistance of two types of steel structures (frame roof, and lattice roof ), for halls (spaces) of different uses (storage and office), we want to get the most economical solution for a particular situation. In addition to the weight of the steel structure, he introduces as a criterion for selecting a particular type of structure and the price of achieving a certain level of fire resistance of the structure, i.e. it is considered the optimality of choosing a particular type of structure through several criteria (weight of the structure, fire resistance...). As part of document, a simulation was performed, using the software package for structures calculations STAAD and SCIA, and a two-zone program package for obtaining of input temperature parameters for structure calculation and resistance analysis construction elements (Ozone). Results will enable a more optimal choice of structure type with regard to resistance to the action of fire, and with regard to its purpose.