It is well known that nonstructural infill elements have failed in many past seismic events, both for in-plane and out-of-plane actions. However, while the in-plane behavior is more investigated, as reported in scientific literature, the out-of-plane aspect needs further developments from modeling and experimental points of view. In this framework, the infill walls adopted in non-recent buildings in large areas of the south of Italy were not conceived to have optimal thermal or mechanical performances but only to fill the concrete frames. They are mainly made of cement-lime mortar and hollow clay-ceramic bricks, cast in place with horizontal holes. In this paper, in the context of the RETURN project, the results of a seismic fragility analysis of typical infill panels, as described above, are presented, accounting for the uncertainties associated with the boundaries, strongly influenced by the workmanship. Boundary restraints influence the demand through the wall period and the capacity according to the failure mechanism. The capacity was validated by incremental analyses on fully 3D finite element models, and the simplified models were characterized based on yield lines theory, scaling capacity to take into account the FE results. Failure probability is finally evaluated for given sites. © 2025 The Authors.