Author of article Dr. Joan-Albert Vinyes
Efflorescences are the white crystals that appear on walls and surfaces, consisting of salts that water has dissolved while in contact with the construction materials. These efflorescences progressively deteriorate walls and floors, and if not completely removed, they prevent proper rehabilitation, as they hinder the good adhesion of construction materials such as mortars, plasters, and paints to the walls.
1. What are efflorescences?
Efflorescences on walls appear when the water that had dissolved them evaporates. They are formed by the powder or white crystals that emerge on the interior or exterior surfaces of a building's walls as the water within the wall evaporates, carrying dissolved construction materials.These salts are generally sulfates, carbonates, or nitrates, which are corrosive to the surrounding materials and cause stains on the wall surfaces.
The origin of the moisture that causes efflorescences can vary, such as:
- Capillary moisture from the surrounding ground, which penetrates walls and floors, dissolving the salts in the construction materials.
- Condensation moisture occurs when ambient humidity settles on cold areas, potentially penetrating walls made of materials that absorb moisture.
- Moisture from leaks, such as water pipe leaks, cracks in walls or ceilings, or underground water currents, saturating the construction materials and consequently dissolving their salts.
- Rainwater that impacts the exterior walls of a home. If these walls are water-absorbent, the surface construction materials may dissolve, leaving behind whitish residues on the surface as the water evaporates.
2. Causes of efflorescences
Efflorescences on walls appear when the water that had dissolved them evaporates. The cause of efflorescences is always water that has dissolved the salts in the construction materials of the walls. Each type can be differentiated by the origin of the water that has penetrated these materials, and the main causes are:
Deficiency in drying or finishing exposed brickwork can cause excess water to dissolve the brick's components, leaving white stains on the wall and the surface of the exposed brick.
Mortar containing sand with sea salt can, when mixed with water during application, dissolve these salts, leading to whitish stains on the exposed brick wall.
Efflorescences on concrete walls not only cause aesthetic damage but can also lead to cracks. In concrete walls, surrounding damp ground or rainwater can dissolve the sulfates in the sand used, resulting in saline efflorescences on the surface and causing cracks in the concrete due to the expansion of these salts when they absorb water.
Capillary moisture is the most common external cause of efflorescences on walls. Water rises from the subsoil through the pores of construction materials, dissolving them as it ascends. These dissolved materials travel up the walls with the water and remain on the surface as the water evaporates.
Condensation moisture tends to generate more mold than efflorescences if the surface materials of the walls do not easily absorb the moisture that settles on them
The most aggressive and rapid cause of wall destruction is leaks. When resolved and dried, they leave a superficial trace of efflorescences on the brick.
3. What are the consequences of efflorescences?
Efflorescences on walls can appear both on the mortar joints and on the bricks. The consequences include:
- On exposed brick walls, efflorescences manifest as white stains that cover the surface, leading to aesthetic deterioration and gradually weakening the brick over time.
- If mortar contains traces of sea salt, it dissolves in water and eventually covers the joints between bricks or the exterior or interior finishing stones.
- On walls with a plaster or mortar finish, the dissolved salts cause the plaster to peel off, resulting in unsightly flakes.
- Even high-quality finish paints can develop bubbles and unsightly peeling due to efflorescences.
- On concrete walls, white stains may appear, and if the sands used contain high levels of sulfates, these can expand when absorbing water, leading to cracks that compromise the structural integrity of the construction.
4. How to Treat Efflorescence Problems?
There are various methods for removing salt efflorescences from walls, but if the underlying moisture issues are not permanently resolved, the efflorescences will inevitably return.
- Lime-based mortars can slow down the process for over a year, but if the moisture is not eliminated within that time, the problems will reoccur.
- The most common method is to remove efflorescences from bricks using high-pressure water and then dry the wall with a heat convector. This process may need to be repeated after a few days.
- Diluted acid treatments require protecting your eyes and hands to avoid damage to skin and eyes. For small areas, you can use vinegar or citric acid diluted 1/10. Another method involves using muriatic acid diluted in water at a ratio of 1/12.
- After application with a brush or roller, it is advisable to let the area rest for 2 days and then rinse the wall with some warm, pressurized water.
5. How to Eliminate Efflorescences
To permanently eliminate efflorescences and prevent them from reappearing, it is essential to address the underlying moisture issues.
Capillary Moisture: This type of moisture originates from the ground, rising through the soil or walls, and can also penetrate walls laterally. The guaranteed solution is the HS-221 electro-physical system.
The HS-221 systemis straightforward to install, requiring no construction work. It can be mounted on a wall in less than 3 minutes.
The HS-221 emits very low-frequency waves (1kHz) through walls and floors, which are certified to be harmless to human health, animals, and plants.
-Condensation Moisture: This type of moisture appears in corners, edges, and the junctions between walls and ceilings. It is caused by the inability to expel interior-generated vapor, which accumulates from activities like cooking and showering.
To address this issue:
- Install Extractors: Place an extractor fan in the bathroom and another in the kitchen. Use them for a few minutes to remove all the excess moisture from the air.
- Forced Ventilation System: Another solution is to install a forced ventilation system. This system draws in outside air, warms it if necessary, and circulates it throughout the house.
-Moisture from Filtration: If the moisture saturating the walls is caused by a leak in a crack in the wall or ceiling, it is crucial to repair it immediately to prevent further damage.
-Moisture from a Drain Leak: If the efflorescences are nitrates and have a foul odor, urgent repair is necessary as the destructive process intensifies daily.
-Rainfall on Water-Absorbing Walls: To prevent this, it is advisable to install a waterproof stone base (about 50 cm high) and apply a water-repellent paint to the wall to repel the water that falls on it.
6. How to Prevent Efflorescences
Several measures can be taken to prevent efflorescences.
- -Use Dry Construction Materials: When building, it’s crucial to use bricks or concrete blocks that do not contain residual moisture and are surface-treated to resist water absorptiono.
- -Select Appropriate Mortar: Use mortar with sand that is free of marine salts or sodium chloride, as moisture can dissolve these salts and cause stains on the exterior when the water used in the mortar evaporates.
- -Install a Waterproof Base: The exterior of walls should be protected with a waterproof stone base, such as slate, to prevent moisture ingress.
- -Apply Water-Repellent Coatings: Exterior walls exposed to rain should have a water-repellent coating to prevent rain from soaking into the finishing materials.
- -Eliminate Indoor Moisture: It is essential to remove any existing moisture inside the building, following the precautions outlined in section 5 on de how to eliminate efflorescenses.
7. Humitat-Stop: Specialists in Capillary Moisture Problems
To address efflorescences on walls and floors caused by capillary moisture,the solution involves drying with the HS-221 and removing the remaining efflorescences using the methods described in section 4.
The HS-221 eliminates capillary moisture and, consequently, the insects associated with it.
The most effective solution for eliminating capillary moisture rising through floors and walls is the installation of the HS-221 system by Humitat-Stop.
Once the floor and wall are dry, the remaining efflorescences can be removed using the previously described methods.
If you suspect you have moisture issues in your walls, contact us for a free diagnosis.
Created by Humitat Stop SL