Introduction
White, powdery patches often appearing on the surface of walls are known as efflorescence. They may seem like a minor cosmetic issue, but they are actually a sign of moisture movement inside the wall. Understanding what efflorescence is, why it forms, and how it can be managed helps homeowners recognise the presence of damp more clearly.
What is efflorescence?
- Efflorescence occurs when water inside a wall dissolves salts from the building material.
- As the water moves outward and evaporates, the salts are left behind on the surface.
- It usually appears as white or greyish powder on plaster, brick, or stone.
Causes of efflorescence
- Rising damp (capillarity)
Groundwater carries salts upwards through masonry and leaves them behind when it evaporates. - Penetrating damp
Rainwater entering through façades or basements can also bring salts to the surface. - Construction materials
Some mortars and bricks naturally contain salts that are released when exposed to moisture. - Poor ventilation
Lack of airflow prevents quick evaporation, intensifying the deposits.
How to identify efflorescence
- White, dusty marks that can be brushed off with a finger.
- Reappearance of stains even after cleaning.
- Usually concentrated in the lower parts of walls, but can appear in basements or façades.
Possible solutions
Cleaning the surface
- Brushing or washing can temporarily remove the salts.
- However, stains often return if moisture persists.
Breathable plasters and renders
- Allow moisture to evaporate while reducing visible damage.
- Provide a longer-term cosmetic improvement.
Ventilation improvements
- Better airflow helps reduce moisture accumulation inside walls.
Non-invasive devices
- Electronic systems (ATE) → influence water movement through electronic impulses.
- Geomagnetic systems (ATG) → use natural fields to act continuously without electricity.
- Both aim to reduce rising damp, which is the main cause of efflorescence.
Conclusion
Efflorescence is not only an aesthetic problem but also a visible sign of moisture activity inside walls. While cleaning and special plasters may improve appearance, the root cause often lies in rising damp or penetrating moisture. Modern technologies like ATE and ATG devices are examples of non-invasive systems that target capillary dampness and help reduce efflorescence over time.
