Which characteristic of masonry walls can lead to the appearance of efflorescence?

The characteristic of masonry walls that can lead to the appearance of efflorescence is saturation with water. Efflorescence occurs when soluble salts contained in the masonry materials are dissolved by water and then carried to the surface as the water evaporates. When the masonry absorbs moisture, particularly if it remains saturated for extended periods, the dissolved salts migrate to the outer surface. Upon evaporation of the water, these salts are left behind, manifesting as visible white, powdery deposits on the masonry surface.

The process is more likely to occur in environments or conditions where there is excessive moisture present in the walls, such as in poorly drained areas or during wet weather. Understanding efflorescence can help in diagnosing moisture problems and addressing potential issues in masonry construction.