The main decay phenomenon of Bernese sandstone is a granular disaggregation. Less frequent, but more specific to these rocks, is a swelling that can be observed in marl-free stones. In stones containing common marl clasts, this swelling is not observed. Marl-free and marl-containing Bernese sandstones behave differently with respect to water absorption through capillary forces, drying, and the location of salt precipitation.