Whether it’s your own house or the rented house, the leakages and seepages are the common problems that are faced by most of the residents. Some of the examples of moisture sources are plumbing leaks, condensation, roof leaks, defective drainage, spillage, ground moisture, rising dampness, uncapped chimney, etc.; you may observe and wonder how the water is rising in a straw, through the sap of trees, through a cloth towel or the way the oil travels up a wick in oil lamps in your daily life. Yes. It is because of the capillary action that takes place. It is the process of the liquid flowing in the narrow spaces even against the gravitational force. In this article, we will be also covering common questions like What causes wall dampness?, What are the different factors that causes dampness in building?, Which method of damp proofing resist the capillary action of water?, Which method of damp proofing resist the capillary action of water?.
When the building materials like bricks, stones, concrete, or plaster come into contact with moisture or dampness, the water adheres to the pores of the material’s capillaries. This may rise to around 1m above its source. The narrower the bore of the capillary tubes is, the higher the water rises. It happens when the adhesion to the wall is stronger than the cohesive forces between the liquid molecules, and the height of the water rise due to the capillary action is limited by the surface tension and the gravity. Rising dampness in the concrete and masonry is also a result of the capillary action.
The capillary action or the rising dampness causes superficial damage to the internal walls and structural damages to timber and masonry. This happens at the ground level when there is an upward movement of moisture from the ground. The visual inspection of the wall exhibits specific changes like tide marks on the walls, crumbling of plaster, decaying of wooden structures close to the base wall, etc., which indicates the water seepage. If the moisture content rises, then the water leaks on the walls through cracks or gaps.
This rising dampness is often misdiagnosed in the existing buildings due to incorrect visual evidence. The rising dampness occurs when there is an upward movement of water through the permeable building materials. This water dissolves and carries the soluble salts (calcium sulfate) along and deposits on the walls or the evaporated surface. If the evaporation of the salt is restricted by a paint finish, then the salts are deposited as crystals, and hence the efflorescence occurs. If the evaporation occurs within the porous building material, then the expanding salt creates fractures and flaking on the wall surface.
The rising dampness affects the base walls, and if the moisture level rises, it destroys the property.
1. It leads to the growth of fungus and molds along the wall surface.
2. The built-in base materials like timber gets infected and decayed by rot or woodworms. 3. Under these damp conditions, the materials and the building lose their structural strength. 4. If the mold grows within the porous materials fitted to the walls like wallpaper or the carpets, it damages the finishes and creates an unaesthetic look.
5. The decay of organisms also pose a health risk/hazard to the occupants like causing allergies, respiratory problems, itchy eyes, etc.,
6. During evaporation of the moisture, the deposition of the soluble salt occurs on the walls and weakens the structure.
7. The peeling of paint or the flaking of the wall happens.
1. Damp Proof Course: As the bricks used for the foundation are porous, the provision of a DPC (1.5-inch thick concrete) on the foundation walls at the plinth level saves it from the ‘Rising Dampness.’ After installing the polymerized rubber-like bitumen rubber material, the brickwork goes up and beds both sides with mortar. This creates a bond between the damp proof layer, mortar, and the walling material that acts as a barrier to moisture and protects the structure.
2. Application Procedure: To achieve this, the damp proof course should be 40 mm thick and made up of cement concrete mix 1:2:4. A good quality waterproofing compound should be added to the concrete, and a uniform layer of bitumen is applied on the top surface. More this, the plastering of the external and internal walls can also be done using waterproofing plaster to avoid damages to the walls during the rainwater splashing.
3. Cavity wall construction: The key to control the rising dampness is allowing the property to breathe. Cavity wall construction helps to provide ventilation to the structure, and the moisture won’t retain anymore. Also, replacing the vinyl flooring or the carpets with any breathable materials reduces the dampness and stops from making it worse.
4. Creating a Moisture Barrier: There are some materials available in the market like treated paper or plastic sheeting that are impervious to water. This can be used on walls and other areas to prevent water penetration and the damages related to it.
5. Surface Water Drainage: The absence of drainage or the blocked drains are the common causes of rising dampness. The faulty drainage pipe spreads the dampness and wet rot and finally infiltrates the walls and the floors. So, the proper maintenance of the surface water drainage helps to prevent the rising dampness issue.
The cost of fixing the defects due to the capillary action depends on the extent of the damages and the most appropriate treatment used. The Dampness conditions can be easily avoided if there is a scientific understanding of the root cause of the problem or detecting the primary source of leakages or seepages. So it’s better to ask for a second or third opinion from the professionals to reduce unnecessary cost treatments and resources. Also, a rational approach is necessary for the proper treatment to protect the building and public health.