Seismic pounding between adjacent unreinforced masonry (URM) façades remains an underexplored topic. A numerical investigation of pounding effects between adjacent URM façades using the discrete element method (DEM) is presented in this study. A validated quarter-scale numerical model was adopted to simulate the dynamic behaviour of clay-brick URM façades subjected to sinusoidal in-plane ground excitation. Model parameters were derived from the material characterisation test and calibrated against an experimental benchmark involving a two-storey URM building. Parametric studies were conducted to explore the influence of façade height variation, separation gap, and opening configuration on building responses subjected to pounding. Results showed that pounding at aligned storey levels produced greater acceleration amplification and displacement demand, particularly in stiffer façades. Narrow separation gap significantly increased pounding forces, with certain thresholds at which the effect became pronounced. Façades without openings experienced more severe damage due to their increased stiffness and lack of local deformation mechanisms. The findings of this study confirm the importance of façade configuration and spacing in controlling pounding-induced damage. Even modest increases in the separation gap were shown to mitigate pounding effects significantly. The outcomes provided insights into the seismic vulnerability of URM buildings constructed in a row and served as a demonstration of the DEM capability to simulate pounding interactions in adjacent masonry structures.