Harmful Effects of Moisture and Salts

Moisture Issues and Salt Efflorescence in Your Home

Excessive moisture and the presence of harmful salts are the two main destructive forces threatening the durability of your home's walls. Moisture, in various forms, can negatively affect the capillary-porous structure of building materials such as stone, brick, and plaster, leading to their degradation. The longer the walls remain damp, the more evident salt efflorescence and material degradation become. This article will help you understand the dangers posed by moisture and salts and how to address these issues.

What You’ll Learn in This Article:

1. What Are the Main Threats to Your Home?
2. Distribution of Salts in Walls
3. What Causes Salt Efflorescence on Walls?
4. Damp Walls – What’s the Cause?
5. How to Deal with Damp Walls and Salt Efflorescence?
6. Selection of Technology and Materials
7. Technology and Materials Consultation
8. Summary of the Article

What Are the Main Threats to Your Home?

Excessive moisture and the presence of so-called harmful building salts are considered the two primary factors contributing to the degradation of wall durability. Water, in its various forms, can negatively affect the structure of capillary-porous materials such as stone, brick, mortar, and plaster, leading to their destruction. The longer the wall remains damp due to capillary absorption, the more noticeable the accumulation of salts and the material degradation process become.

What Are the Main Threats to Your Home?

Salts can occur as natural components of building materials or infiltrate wall structures in the form of water solutions from the surrounding environment. The three main groups of salts that pose the greatest destructive potential and threaten wall durability are chlorides, nitrates, and sulfates.

• Chlorides typically originate from substances used for de-icing roads and sidewalks during winter.
• Nitrates can result from the oxidation of organic matter or fertilizers.
• Sulfates are often linked to air pollution caused by sulfur dioxide (acid rain). These compounds may also be present in groundwater.

From a construction perspective, the greatest danger lies in water-soluble salts, as they can only penetrate building materials when dissolved in water. Water plays a crucial role in transporting these salts through building structures.

The behavior of salts in porous wall materials and their effects on walls depend on several factors:

• Concentration
• Solubility
• Temperature
• Ambient humidity

Distribution of Salts in Walls

The distribution of salts along the height of a wall depends on their chemical composition.

• Calcium sulfates and carbonate salts are most often found at ground level.
• At heights up to 0.5 meters, magnesium and sodium sulfates, as well as potassium nitrate, are commonly present.
• Higher up in the wall, chloride compounds and nitrates tend to concentrate.

Nitrates are particularly dangerous due to their hygroscopic properties, which enable them to attract moisture from the air. This increases the availability of water within the wall structure, exacerbating damage.

In most cases, the risks posed by harmful building salts do not exceed a height of 0.5 meters above the ground.

What Causes Salt Efflorescence on Walls?

The most visible manifestation of salts in walls is efflorescence, which can appear both inside and outside buildings. On the surface of materials, efflorescence can take various forms, such as stains, droplets, salt deposits, loose white residues, or even shiny crusts. The appearance of efflorescence depends on the type and quantity of salts and the conditions under which the crystallization process occurs.

The Process Behind Salt Efflorescence:

1. Crystallization Within the Wall Structure:
   When the rate at which salt solutions are delivered to the surface is lower than the rate of water evaporation, salt crystallization occurs deeper within the wall structure. This process leads to surface degradation, including detachment of plaster and damage to deeper layers of the wall.
2. Stress from Crystallization:
   The stress caused by salt crystallization in the pores of the building material results in damage. Crystallization occurs when the concentration of salts reaches saturation. Importantly, this process does not stop once the pores are filled with salt crystals; it continues, causing increasing pressure inside the pores.
3. Material Damage:
   When the pressure from crystallization exceeds the tensile strength of the building material, permanent structural damage occurs. This leads to visible deterioration, such as cracking, flaking, or complete disintegration of the material.

Damp Walls – What’s the Cause?

The salt content in a wall significantly impacts its water absorption properties. Some harmful building salts exhibit hygroscopic properties, meaning they draw water from the surrounding humid air. This increased capacity for absorbing moisture leads to localized damp patches on walls and plaster, often appearing as dark stains.

Key Factors Contributing to Damp Walls:

1. Hygroscopic Salt Activity:
   Certain salts within the wall structure absorb water from the ambient air, resulting in damp areas on the wall's surface. These patches are more pronounced in environments with high humidity and in walls with high salt concentrations.
2. Moisture Uptake Influenced by Salt Concentration and Air Humidity:
   The amount of water absorbed depends on the salt concentration in the wall and the relative humidity of the surrounding air. In heavily salted walls, the moisture absorbed from the air can be comparable to the amount of moisture transported from the ground through capillary action.
3. Slow Drying in Salt-Laden Walls:
   Walls with high salt content retain moisture for extended periods, making them particularly slow to dry. This exacerbates the dampness problem, as the presence of salts continuously draws moisture into the structure.

The combination of hygroscopic salt activity and environmental conditions results in persistent dampness, significantly affecting the durability and aesthetics of walls. Proper remediation requires addressing both moisture sources and the presence of salts.

How to Deal with Damp Walls and Salt Efflorescence?

The renovation process for damp walls always requires a tailored approach, as every case is unique. The first step in drying out a building is accurate diagnostics, aiming to address the root cause of the problem rather than merely treating its symptoms.

Steps to Address Damp Walls and Salt Efflorescence:

1. Comprehensive Diagnostics: Diagnosing the building includes:
   • Analyzing the structure.
   • Identifying the causes of damage.
   • Determining the scope of necessary repairs. Proper diagnostics are crucial for effectively addressing moisture and efflorescence issues. A poor assessment or insufficient investigation is one of the main reasons renovation efforts fail.
2. Collaboration with Specialists: Success in remediation depends on close collaboration with qualified specialists, including designers, contractors, and suppliers of appropriate technologies and materials.
3. Tailored Solutions: A professional approach ensures that the specific needs of the building are addressed using the most suitable methods, materials, and technologies.