White efflorescence on brickwork: causes, prevention, and solutions
- Dutchbricklayers
- Apr 20
- 3 min read
What is white efflorescence?
(The following information is specifically tailored to the Dutch climate and construction practices)
White efflorescence is a white, powdery or blotchy deposit that appears on the surface of brickwork. It commonly occurs on new facades but can also appear years later. While usually harmless, it can affect the appearance of a wall. In some cases, the efflorescence is persistent and keeps returning if the root cause isn’t addressed.
The efflorescence occurs when water-soluble salts—originating from bricks, mortar, or concrete—dissolve due to moisture and migrate to the surface of the wall through evaporation. Once the water evaporates, these salts are left behind as a white haze or crust on the brick or joint.
Causes of white efflorescence
White efflorescence is almost always the result of moisture movement combined with soluble salts present in the building materials. These are the main causes:
Soluble salts in bricks and mortar Natural materials like clay and sand naturally contain salts such as sodium, potassium, and calcium sulfates. These salts can be activated during manufacturing or processing.
Moisture during and after construction Rain, construction moisture, or condensation can penetrate the masonry and dissolve the salts. This moisture then migrates to the outside surface, carrying the salts with it.
Insufficient drying or protection brickwork that isn’t well protected from rain, or bricks that get wet on the scaffolding, are more susceptible to efflorescence. Long-term exposure to moisture, such as from planters or leaks, also often leads to white staining.
Poor detailing or water drainage Facades without proper flashings, drip edges, or those in frequent contact with wet soil will develop efflorescence more easily.
Different types of efflorescence
Not all white staining is the same. The most common types include:
Salt efflorescence: A light, white haze that often disappears after the first rainfall but may return. This is the most common and usually harmless.
Calcium efflorescence: More persistent and harder to remove. Often caused by cement-based materials such as concrete or mortar.
Crystalline efflorescence: Looks like sugar crystals. This typically forms from calcium carbonate or sulfate and often penetrates deeper into the material.
How to prevent white efflorescence
While white efflorescence can’t always be entirely prevented, the following measures can significantly reduce the risk:
Use the right materials Choose bricks and mortars with low soluble salt content. Use low-efflorescence mortars. Check for certifications and ask manufacturers for product data.
Keep materials dry on site Store bricks and mortar protected from rain. Do not use materials that have become wet.
Work in suitable weather conditions Avoid bricklaying work during wet weather or frost. Ideally work between 5 and 25 °C, without direct rain or sunlight.
Protect fresh brickwork properly Cover freshly laid walls with waterproof sheeting to prevent rainwater from soaking in before the structure has cured.
Ensure proper detailing and water drainage Install drip edges, correct roof overhangs, and a wall design that prevents water from running down over bricks and joints.
Waterproofing (Hydrophobing) In some cases, a facade can be treated with a water-repellent agent after cleaning. This prevents further moisture absorption and future efflorescence.
How to remove white efflorescence
If efflorescence has already appeared, there are several methods to remove it:
Brushing Dry salt efflorescence can sometimes be brushed off with a soft, dry brush. Ideally do this in dry weather.
Chemical cleaning Stubborn calcium-based efflorescence may require an acidic cleaner, such as a diluted solution of sulfamic acid. This should be done professionally with proper safety precautions. Always test on an inconspicuous area first.
Professional facade cleaning If the efflorescence has penetrated deep into the brick or keeps recurring, it’s advisable to consult a professional facade cleaning service.
Is white efflorescence harmful?
In most cases, white efflorescence is purely aesthetic and not harmful to the masonry itself. However, if the root cause is moisture-related (such as leaks or rising damp), it can eventually lead to structural damage. Regular inspection and maintenance are therefore essential.
Summary: tips for clean facades
✔ Choose low-efflorescence materials – this is also available for pointing mortars nowadays
✔ Store bricks and mortar dry on site
✔ Protect new masonry from weather for at least 48 hours
✔ Only work in suitable weather
✔ Clean facades carefully using appropriate methods
✔ Consider water-repellent treatment in case of ongoing moisture issues
White efflorescence isn’t something to panic about, but it is a sign that moisture has found its way into your wall by making the right choices in design, during construction, and through proper maintenance, many problems can be avoided—allowing you to enjoy a sleek, clean facade for years to come.
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