Efflorescence: What It Is, Causes, and How to Remove It

Efflorescence refers to white, grainy, irregular stains that appear on surfaces exposed to moisture, such as brick walls, ceramic tiles, joints, and concrete. These stains are common on building facades and walls. Efflorescence happens when water moves through porous materials, carrying dissolved salts. As the water evaporates, the salts crystallize on the surface, leaving white marks.

While efflorescence usually affects the exterior surface and paint, it can sometimes damage the underlying structure by causing wear and tear.

Let’s explore what causes these white stains, the problems they can create, and how you can prevent and remove them effectively.

Why Does Efflorescence Occur?

Efflorescence occurs when water dissolves salts in porous materials and brings them to the surface. As the water evaporates, the salts crystallize and form visible stains. Key reasons for efflorescence include:

• Presence of Soluble Salts: Construction materials like bricks and concrete contain salts such as sulfates, carbonates, and chlorides. These dissolve in water and migrate to the surface.
• Water Exposure: Water from leaks, condensation, or capillary action moves the salts through the material.
• Water Evaporation: As water reaches the surface and evaporates, the salts are left behind, forming white stains.
• Construction Defects: Poor waterproofing, inadequate drainage, porous materials, or faulty construction make it easier for water to enter and cause efflorescence.
• Environmental Conditions: Temperature, humidity, and rain exposure can speed up or worsen efflorescence formation.

Example:

Brick wall in a garden where sprinklers are used daily. Over time the water from the sprinklers seeps into the bricks and dissolves the salts inside. As the sun dries the wall white stains appear. These are efflorescence caused by the salts being left behind when the water evaporates.

Types of Efflorescence

Efflorescence can be classified into two types based on its origin:

• Primary Efflorescence: This appears on newly built structures due to initial moisture. It often disappears after a few months without leaving permanent marks.
• Secondary Efflorescence: This occurs in older buildings, usually due to construction defects or unsuitable materials. High porosity and moisture problems can also lead to secondary efflorescence.

Example:

Homeowner notices white stains on the basement walls of an old house. Upon investigation they find a small crack in the foundation which has allowed water to get into the walls. Moisture has been present for so long it has caused secondary efflorescence.

Problems Caused by Efflorescence

Efflorescence often creates surface-level problems like stains or peeling paint. However, it can sometimes lead to more severe issues, such as:

• Cryptoflorescence: This occurs inside materials and can cause significant damage. The salts accumulate in wall pores, expanding their volume and causing surfaces to peel, bricks to crack, and coatings to fall off.

Example:

Efflorescence on the interior walls of a commercial building caused peeling paint and plaster. Further investigation found salts had built up inside the walls and required costly repairs.

How to Prevent Efflorescence

Preventing efflorescence requires a combination of good construction practices and regular maintenance. Here are some steps to minimize its occurrence:

• Control Humidity: Use proper ventilation, dehumidifiers, or fix condensation issues to reduce indoor moisture levels.
• Waterproof Surfaces: Ensure walls and surfaces are well waterproofed to prevent water infiltration.
• Improve Drainage: Ensure water drains away from your property to avoid pooling near walls and foundations.
• Seal Porous Materials: Apply sealants to bricks, concrete, or stone to reduce water absorption.
• Regular Maintenance: Inspect surfaces for moisture damage or cracks and fix issues immediately.
• Use Quality Materials: Build with water-resistant materials and follow best construction practices.
• Hydrophobic Materials: During construction, use water-repellent bricks, mortar, and coatings to prevent water absorption.

Example:

Contractor builds a new office uses water-repellent bricks and applies a sealant to the exterior walls. They also install proper drainage around the building so water can’t accumulate. And efflorescence free for years to come.

How to Remove Efflorescence

Efflorescence removal requires identifying and addressing the source of moisture first. Here’s how to handle different types of efflorescence:

1. Capillary Moisture

• Fix the source of moisture, such as drainage or waterproofing issues.
• Wash the surface with water and a natural-bristle brush.
• If the stains persist, use a mild hydrochloric acid cleaner to dissolve the salts.

Example:

Homeowner notices white stains on their garden wall. Fixes the drainage problem and scrubs the stains with a brush and water. Some stains remain so they use a commercial acid cleaner to remove them.

2. Condensation Moisture

• Reduce indoor humidity with better ventilation, dehumidifiers, or insulation.
• Clean the surface with water and soap to gently remove the stains.
• Dry the area thoroughly after cleaning.

Example:

Poor ventilation in a bathroom causes efflorescence on the tiled walls. Homeowner installs an exhaust fan and a dehumidifier. Cleans the tiles with soap and water and the stains don’t come back.

3. Leakage Moisture

• Identify and repair leaks in walls, ceilings, or roofs.
• Apply waterproof coatings or sealants to prevent future water infiltration.
• Ensure proper drainage around the structure.

Example:

An apartment complex experiences efflorescence on multiple balconies. A thorough inspection reveals small cracks in the balcony flooring, allowing water to seep in. The management repairs the cracks, applies a waterproof coating, and resolves the issue.

Guide to Efflorescence Removal

FAQs About Efflorescence

1. Can efflorescence damage walls permanently?

Efflorescence itself usually doesn’t cause permanent damage, but it can lead to structural issues if left unaddressed.

2. Is efflorescence harmful to health?

No, efflorescence is not harmful, but the moisture that causes it can lead to mold growth, which may affect health.

3. How long does it take for efflorescence to go away?

Primary efflorescence often fades in a few months, but secondary efflorescence requires fixing the underlying problem to stop recurring.

4. Can I prevent efflorescence during construction?

Yes, using water-repellent materials, proper waterproofing, and good drainage design can prevent efflorescence during construction.

Key Takeaways

• Efflorescence forms when water carries salts to the surface of porous materials, leaving white stains after evaporation.
• Preventing efflorescence involves controlling moisture, improving drainage, and using quality materials.
• Removing efflorescence requires addressing the moisture source and cleaning the affected area with appropriate tools and techniques.

Regular maintenance and proactive measures can keep your property free from efflorescence and its effects.