What is Efflorescence?

Efflorescence is the white, powdery residue that sometimes appears on the surface of concrete, brick, or masonry. It occurs when water within the material dissolves soluble salts. As the water migrates to the surface and evaporates, it leaves those salts behind. The result is a chalky or crystalline coating that, while usually harmless, can be unsightly and indicate moisture movement through the structure.

Efflorescence is often a sign of excess moisture, poor drainage, or inadequate sealing. While it's not typically a structural concern, repeated or heavy efflorescence can point to underlying issues that may lead to long-term damage, such as cracking, spalling, or mould growth. Addressing it involves improving waterproofing, drainage, or ventilation—and in some cases, treating the surface with a mild acid or specialized cleaner.

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