Clay-related damage in rainscreen walls built with natural stone coverings

Clay particles found in many building stones, when in contact with water, suffer aggregation–disaggregation and swelling–shrinking processes which can cause severe pathology. Whilst research has focused on historic buildings and masonry walls, studies regarding rainscreen walls are lacking. When using panels of reduced thickness fixed with punctual anchorage points, fissures or scaling phenomena can rapidly lead to rupture of panels, causing stability failure. This study aims to identify the causes of decay in a building with limestone rainscreen walls, in order to help to understand clay-related damage in this type of façade and its differences with regard to masonry walls.

▸ Undetected clay presence has led to removal and replacement of all stone panels. ▸ Heterogeneity leads to a different decay pattern in each sedimentary facies. ▸ Fractures parallel to bedding planes favor absorption, swelling and mass loss. ▸ Speed and magnitude of damage increase with wetting time. ▸ Inner surfaces are not affected; outer ones get more permeable, accelerating decay.