The construction site geotechnical conditions are an important factor in the structures seismic resistance estimation. Based on the earthquakes consequences analysis to buildings with the same structural schemes and overall dimensions, the construction site estimated seismicity dependence on the base soil seismic stiffness and the transverse waves speed is fixed in the seismic building design code. In the research, a math modeling experiments for completely identical structures, but with different foundations types on identical soil conditions, were performed. The performed calculations analysis showed a significant discrepancy in the structures response under seismic impact for different foundations types.