What causes efflorescence on masonry units?

Efflorescence occurs when soluble salts present in masonry units or the materials used for construction are brought to the surface by moisture. When water moves through the masonry, it can dissolve these salts, and as the moisture evaporates, the salts are left behind on the surface of the brick or block as a white powdery deposit. This is primarily a result of moisture retention in the masonry during periods of humidity or after rain, and therefore, the presence of excess water is a direct cause of efflorescence. Proper drainage and moisture management are essential to prevent such conditions in masonry structures.