Uploaded June 2024 | Updated September 2026, 3 weeks ago
Understanding efflorescence
What is efflorescence?
Efflorescence refers to the unsightly white, chalky substance on concrete or other masonry surfaces. It is a natural process when mineral salts from within the material rise to the surface due to moisture.
When the water evaporates, it leaves behind these salts, primarily calcium carbonate.
The efflorescence process is often triggered by the chemical reaction between lime deposits in the cement and carbon dioxide in the air.
What causes efflorescence?
Three conditions need to exist for efflorescence to occur:
1) There are water-soluble mineral salts in the material.
2) Moisture is present to make the salt become a soluble solution.
3) As salts move to the material’s surface, the moisture evaporates. This makes the salts crystallise, which results in efflorescence.
Preventing efflorescence
Taking care of building materials before, during, and after construction can help prevent efflorescence.
Here at FP McCann, our concrete products are manufactured with a water-based acrylic sealer mixed into the concrete. This sealer helps slow the risk of lime deposits to the surface, significantly reducing the likelihood of efflorescence.
Dealing with efflorescence
If efflorescence appears on your roof tiles, it is usually just a cosmetic issue that won’t affect the roof's structural integrity.
You can also use an efflorescence cleaner (but it is important to choose the right one for your situation), rinse the building surface with water, or simply brush the surface to remove built-up efflorescence.
If you have any questions on efflorescence, don't hesitate to contact the team here at FP McCann; we will be happy to help.
Visit our website for full details on our concrete roof tile range fpmccann.co.uk/uk/concrete-roof-tiles
Understanding efflorescence
What is efflorescence?
Efflorescence refers to the unsightly white, chalky substance on concrete or other masonry surfaces. It is a natural process when mineral salts from within the material rise to the surface due to moisture.
When the water evaporates, it leaves behind these salts, primarily calcium carbonate.
The efflorescence process is often triggered by the chemical reaction between lime deposits in the cement and carbon dioxide in the air.
What causes efflorescence?
Three conditions need to exist for efflorescence to occur:
1) There are water-soluble mineral salts in the material.
2) Moisture is present to make the salt become a soluble solution.
3) As salts move to the material’s surface, the moisture evaporates. This makes the salts crystallise, which results in efflorescence.
Preventing efflorescence
Taking care of building materials before, during, and after construction can help prevent efflorescence.
Here at FP McCann, our concrete products are manufactured with a water-based acrylic sealer mixed into the concrete. This sealer helps slow the risk of lime deposits to the surface, significantly reducing the likelihood of efflorescence.
Dealing with efflorescence
If efflorescence appears on your roof tiles, it is usually just a cosmetic issue that won’t affect the roof's structural integrity.
You can also use an efflorescence cleaner (but it is important to choose the right one for your situation), rinse the building surface with water, or simply brush the surface to remove built-up efflorescence.
If you have any questions on efflorescence, don't hesitate to contact the team here at FP McCann; we will be happy to help.
Visit our website for full details on our concrete roof tile range fpmccann.co.uk/uk/concrete-roof-tiles
