What consequence might excessive moisture in a wall lead to with regard to efflorescence?

Excessive moisture in a wall can result in efflorescence, which is the white, powdery substance that appears on surfaces when water evaporates, leaving behind mineral deposits such as salts. The process starts when moisture penetrates the wall, usually through cracks or porous materials. As this moisture evaporates, it can bring these minerals to the surface of the wall, creating efflorescence.

More importantly, if the moisture problem is severe, it can lead to spalling. Spalling occurs when the volume of the moisture within the building material expands as it freezes or increases pressure from salt deposits, causing parts of the surface to break away, flake, or even crumble. This not only affects the aesthetic appearance of the wall but can also compromise the structural integrity of the building materials over time. Thus, the connection between excessive moisture and spalling highlights the potential damage that can occur due to ongoing moisture issues, making this the correct answer.