Efflorescence
Efflorescence: white salt deposits on masonry surfaces caused by water carrying soluble salts to the surface. A common indicator of moisture ingress or DPC failure.
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Efflorescence is the white or grey crystalline deposit that forms on masonry surfaces when water carries soluble salts (calcium sulphate, sodium chloride, potassium carbonate) through the masonry and deposits them as the water evaporates at the surface. It is a symptom of moisture movement through brickwork, blockwork, or concrete. In new construction, a mild bloom of efflorescence in the first year is common as curing water works its way out; persistent or recurring efflorescence after that is a signal of ongoing moisture ingress, a missing or bridged damp-proof course, blocked weep holes, or inadequate flashing.
Efflorescence is generally cosmetic in mild cases but indicates a moisture pathway that, left unaddressed, can cause mortar joint deterioration, spalling, and internal water damage. The source of moisture must be fixed, not just the surface deposit. Surface cleaning with dilute acid removes the bloom but does not address the underlying cause.
Also known as: white staining, salt staining, salt bloom.
Category: Masonry / defects / waterproofing.
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Last updated: 2026-05-10. Verified: 2026-05-10.