The development of crack patterns in masonry structures is a completely normal occurrence, representing the capacity of the structure to find a geometric equilibrium configuration that is adapted to certain external conditions and caused, primarily, by its inability to sustain tensile forces. A major source of damage to masonry structures is foundation settlement, which can be caused by foundations standing on different types of soil as well as human actions such as excavations for the construction of underground parking lots or tunnels. Therefore, it is necessary to develop numerical tools to predict the settlement mechanism in masonry walls that may be caused by construction work being carried out in the neighborhood or, conversely, to identify the cause of pre-existing crack patterns. In this paper the specific case of masonry walls subject to foundation settlements is analyzed. A numerical tool based on a rigid block model with slightly compression-deformable joints is developed. Foundation settlement is entered as an inelastic distortion impressed on the joints at the base of the settled zone. The procedure allows horizontal, vertical, rotational or mixed displacements to be considered. Furthermore, since these wall structures are made of individual blocks, their behavior is highly nonlinear and, therefore, the proposed procedure is nonlinear and iterative. Iterations are used to satisfy the failure criteria assumed for the analysis, mainly the no-tensile strength and finite friction based on Mohr-Coulomb criterion. The reliability and robustness of the procedure are demonstrated by comparing experimental results with numerical outcomes.