This study presents the results of a critical analysis of the existing methods of selecting the values of ground deformation modulus used in calculating the settlement of designed foundations. The importance of improving the reliability of the determination of the modulus of deformation for ensuring the reliability, economic efficiency and safety of structures is highlighted. It is revealed that the determination of the deformation modulus is not performed at the full depth of soil samples, which can lead to the risk of accidents at facilities. To increase the reliability of deformation modulus determination, a method of interpolation of values based on data from nearby wells is proposed. A new model for determining intermediate values of the deformation modulus is presented, which can be used in calculating the settlement of designed buildings. The results of test problems confirm the high efficiency of the proposed method not only for the calculation of foundation settlement using the values of ground deformation modulus, but also for the control determination of refined values of ground deformation modulus at the stage of geotechnical engineering surveys.