The working of buildings with load-bearing walls made of masonry has a significant difference from the working of buildings made of monolithic and precast concrete: the degree of damage, coefficient of variation, and overall stiffness differ. One of the most difficult issues in calculating load-bearing masonry structures for seismic impacts is determining the relative shear deformations of walls of rigid stone buildings. The calculation of these deformations on a straight line depends on the cross – section shape coefficient-a coefficient that takes into account the influence of uneven tangential stresses on the deformation of the bent element. This article presents the results of analytical studies of the dependencies of the cross-section shape coefficient. In conclusion, we present an analytical method for determining this coefficient, which allows us to determine the rigidity of a wall structure of any shape with a sufficient level of accuracy and, as a result, adequately take into account the shear forces in the vertical joints of the wall interface.