What Is Efflorescence and How to Treat it?

What is efflorescence?

Efflorescence is a type of white deposit that can be found on brickwork, concrete, and masonry. The white marks are actually crystalline salt that has formed when excess water dissolves the salts that are naturally found in construction material and mortar. The salty water is then carried to the surface, and when it hits the air, it evaporates away, leaving the salt behind.

Efflorescence is not dangerous, but it can be unsightly and cause paint and wallpaper to peel off the walls.
It also indicates that the surface where it has been found has been wet, suggesting a moisture issue that needs to be investigated and addressed.

While efflorescence doesn’t typically cause long-term damage, the presence of moisture could lead to further complications such as structural issues if left unchecked. It’s crucial to get to the root cause and fix the problem.

What causes efflorescence?

Efflorescence can occur for various reasons, including:

Water leaks: Damaged masonry, faulty guttering, or water intrusion.
Severe condensation problems that cause moisture to accumulate.
Improperly stored construction materials: Bricks or other materials left out in the rain may absorb moisture, leading to efflorescence when they dry out.

If you have efflorescence caused by wet materials, you will need to wait until the surface has dried completely before addressing the issue.

According to a 2025 report from the UK Green Building Council, building moisture issues are one of the leading causes of structural deterioration in older buildings, often linked to efflorescence. Proper treatment and regular maintenance can extend the life of your property by up to 30%.

Treating efflorescence

The best way to treat efflorescence is to:

Find the source of water ingress. This is essential to prevent the problem from recurring.
Clean the affected area. For external walls, a good scrub with a dry brush will help remove the salts and stop them from re-dissolving.

For internal walls, using a salt neutraliser is recommended. This special product prevents salts from reacting with water and can be used on:

Bare plaster
Stone
Brick
Render (not on paint or wallpaper)

Key tip: Be sure the source of the damp is properly fixed before using a salt neutraliser to avoid future issues.

Finding the source of the water ingress and a good scrub is the best solution for efflorescence that appears on external walls. Fixing the problem that has caused the excess water to leave salt deposits on external walls will help to prevent it from happening again and the visible staining should be removed by scrubbing the area with a dry brush to prevent the salts re-dissolving.

You can treat efflorescence on internal walls using a special product called salt neutraliser. This product is designed to stop the salts reacting with water and can be used on bare plaster, stone, brick or render – not over paint or wallpaper. However, you must be sure the cause of the damp has been found and fixed before using this product.

Croft Preservation: Your Local Damp Experts

Croft Preservation is Dorset and Hampshire’s leading expert in damp issues. If you are struggling with efflorescence or suspect you have a moisture problem, our experienced team can help. We will identify the root cause and provide you with a cost-effective solution that protects your property.

To get in touch with us, call 01202 737739 today, and speak with our friendly team for expert advice.

What is efflorescence?