Posted: 06 June 2025
Explaining Efflorescence in brickwork and how to combat it.
What Is Efflorescence in Brickwork?
Efflorescence is most prevalent in the early life of a building, particularly appearing in the first year after construction. Often mistaken for mold or dust, efflorescence is a powdery deposit formed through a chemical process that appears on brick surfaces. It forms when water moves through the brick, bringing salts to the surface. As the moisture evaporates, salt is left behind.
At its core, efflorescence is a crystalline deposit of salts. It is not harmful in the way mold or mildew can be, but it’s an eyesore and a clear sign that moisture is present where it shouldn’t be.
The salts can come from several sources:
The Clay Bricks - Clay bricks are particularly prone to efflorescence. During manufacturing, certain salts are naturally embedded into the bricks. Please see a handy guide to how bricks are made.
Mortar mix - especially lime or cement based mortars. These mixes can contain various soluble compounds that when exposed to moisture can easily leach out and appear as surface deposits.
External factors - such as soil, groundwater or the UK weather, frequent rain and the mixture of high humidity and cold winters all contribute to the likelihood of efflorescence.
The process relies on three things: soluble salts, moisture, and evaporation. Eliminate any one of these, and you’ll reduce the likelihood of efflorescence.
Visual Signs of Efflorescence
You can spot signs of efflorescence in brickwork in a number of ways:
Chalky white or greyish stains on the surface of the bricks
Flaky surface texture when brushed
Stains appear after rain or during winter.
This effect usually starts small but can spread fast without attention. It’s important to distinguish efflorescence from mold, which feels softer and may darken when wet.
How to avoid Efflorescence in brickwork.
Little if any brickwork is immune from efflorescence, factors which can cause issues include:
Design and detailing - Lack of protection in cills and copings.
Brick Storage - Bricks should be stacked onto a clean level surface and should be protected from rain and mud splashes.
Construction Practices - Newly erected brickwork should be covered to protect cavities and stop masonry becoming saturated.
Site Exposure - Specific building elevations can be more at risk than others due to their position in relation to prevailing wind and rain conditions. Also particular areas of exposed brickwork e.g. parapets.
Salt Rating - All of Traditional Brick & Stone brick range have a S2 salt rating, the lowest level of soluble salts.
Treatment of Efflorescence
Efflorescence should preferably be allowed to weather away naturally however, below there are some DIY cleaning methods that we recommend:
Dry Brushing - Use a stiff nylon brush, this is often enough for light deposits. Please not use a wire brush.
Rinse with water - Wash the area with clean water, avoid pressure washers as this can force salts deeper into the brickwork.
The use of a silicone treatment should be avoided since this can result in more permanent problems.
Conclusion
Efflorescence is a common issue on new brickwork in the UK and a sign of moisture and salt interaction.
Ensuring use of quality materials, good site practices, and maintenance, your brickwork can continue to look as good as new!
You may also like...
