Efflorescence
White crystalline deposits left on a surface when water moving through masonry or concrete evaporates and leaves dissolved salts behind.
On an actual building
It is not the problem — it is evidence of one. Efflorescence proves water is moving through the material and shows you where it is leaving. Recurring deposits after cleaning mean the water path is still open.
What we most often have to correct
That it is a surface stain to be cleaned off. Brushing it away treats the symptom; the salts return every season until the water is stopped.
Where this comes up in our work
Terms that come up alongside this one
- Rising Damp
Ground moisture drawn upward through the pores of masonry by capillary action, typically producing a horizontal tide mark and salt deposits..
- Capillary Action
The movement of liquid through narrow spaces against gravity, driven by surface tension.
- Salt Crystallisation
Damage caused when salts dissolved in moisture crystallise within the pores of masonry or plaster, exerting pressure as they grow..
More deterioration terms
Efflorescence — questions we get asked
What does efflorescence mean in waterproofing?
White crystalline deposits left on a surface when water moving through masonry or concrete evaporates and leaves dissolved salts behind.
Why does efflorescence matter on a real project?
It is not the problem — it is evidence of one. Efflorescence proves water is moving through the material and shows you where it is leaving. Recurring deposits after cleaning mean the water path is still open.
What do people commonly get wrong about efflorescence?
That it is a surface stain to be cleaned off. Brushing it away treats the symptom; the salts return every season until the water is stopped.
Have a building showing this?
If a term on this page describes something you are looking at, a site inspection will tell you how far it has gone and what it needs. It costs nothing.
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