What is the primary cause of efflorescence on masonry structures?

Efflorescence primarily occurs due to excess moisture within masonry structures. When water penetrates the masonry, it can dissolve soluble salts present in the materials. As the moisture rises to the surface through evaporation, it leaves behind these salts, forming a white, powdery substance known as efflorescence. This phenomenon is not only an aesthetic concern but can also signal potential underlying moisture problems that may need to be addressed.

While other factors such as cracking in the masonry, improper curing, and the use of low-quality materials may contribute to the conditions that allow moisture to remain trapped or penetrate more easily, the direct cause of efflorescence itself is the presence of excess moisture allowing the salt migration. Understanding this helps masonry professionals take preventative measures, such as improving drainage and ventilation, to minimize moisture intrusion and subsequent efflorescence.