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What is Rising Damp and how to solve this issue?

Rising damp occurs when water from the ground ascends penetrating the walls. Discover causes, effects, and remedies to prevent structural damage.


Rising damp represents a widespread issue that can significantly compromise the quality of indoor spaces in buildings, causing both structural and aesthetic damage.

This phenomenon can be exacerbated by other forms of moisture such as condensation or by improper calculation of thermal bridges, which promote mold formation. To identify thermal bridges that can exacerbate rising dampness, you may find it useful to use thermal bridge calculation software that guides you in careful planning, aimed at minimizing the impact of thermal bridges already in the design phase.

Explore in detail what rising dampness is, its causes, effects, and methods to prevent the problem.

What Is Rising Damp?

Rising damp, also called capillary ascending moisture, is a phenomenon in which water from the ground rises along the walls of the building, carrying soluble salts that can deposit on the wall surface, causing salt efflorescence, stains, halos, and other damages.
This phenomenon is made possible by capillarity, which allows water to pass through the pores of materials such as concrete, brick, and plaster.

Its origin often lies in the building’s foundations and can be caused by the lack or ineffectiveness of the waterproofing system of structures in contact with the soil.

Which Areas Are Affected by Rising Damp?

The problem of rising dampness originates in the foundations, and typically affects the external walls of ground floors and basements, but can also affect other parts of the building, such as horizontal floors, causing problems to floorings.
The height reached by rising damp depends on the material of the walls; for example, concrete, which is usually less porous than bricks, absorbs less moisture.

Common cases of dampness include bathrooms, cellars, and garages.

In cellars and garages, for example, dampness can be worsened by the absence of light and ventilation: these areas, often without windows or located in basements, are subject to the accumulation of moisture over time, also due to distinct causes.

For more details, read How to design a garage.

Causes of Rising Damp

The true cause of the damage is not so much the water itself, but the mineral salts it contains, which crystallize during evaporation and increase in volume, causing capillary rise inside the walls.
Factors that can act individually or in combination, creating the ideal conditions for the formation of rising dampness on building walls, include:

  • absence or inadequacy of waterproofing of building foundations: waterproofing of foundations is essential to protect the structure from water naturally present in the soil and from rising dampness phenomena;
  • use of extremely porous building materials: materials such as concrete, bricks, stone, and blocks tend to absorb water, contributing to capillary rise;
  • buildings not raised from the ground or lacking proper ventilation on the ground floor: buildings that are not raised from the ground or lacking proper ventilation on the ground floor are more susceptible to rising dampness formation;
  • moisture problems or water presence in the ventilated crawl space: any moisture problem or water accumulation in the ventilated crawl space can contribute to rising dampness. To avoid this risk, it is essential to design and integrate the crawl space starting from 2D drawings (sections, construction details, etc.) and complete 3D models with specific indications on the execution methods and technical characteristics of the components to be used. To do all this, the use of 3D architectural design software can be of great support, allowing you to obtain executive graphic documents directly from the BIM model of the building.

Effects of Rising Damp

The effects of rising dampness are often evident and represent key elements for recognizing this phenomenon:

  • plasters peeling or crumbling;
  • evident moisture in the joints between floor and wall tiles;
  • disintegration of mortars;
  • yellowing or detachment areas in painting;
  • damage or detachment of wooden skirting boards;
  • appearance of mold and deposits of saline dust;
  • presence of halos and stains on walls;
  • unpleasant odors of must, mold, and staleness;
  • damage to furniture and upholstery.

How to Recognize Rising Damp on Walls

Rising dampness appears in parts of the wall that are in direct contact with the ground.
Other phenomena may manifest similarly and may be easily confused with it, including:

  • lateral infiltration dampness, caused by rain hitting the external walls of the building or by water splashes from puddles generated by vehicles;
  • leaks from plumbing;
  • damage to internal rainwater pipes;
  • groundwater dampness, similar to capillary rising dampness but influenced by specific atmospheric phenomena such as snow melting in the mountains or heavy rains.

There are unique characteristics that allow identifying rising dampness compared to other forms of wall moisture, such as condensation. These distinctive features include:

  • the presence of a uniform stain that develops from the floor upwards;
  • the clear definition of the edge of the stain, usually limited to a height of less than a meter;
  • the persistence of the stain despite climatic and relative humidity variations;
  • the presence of salts during periods of high environmental evaporation.

Among the contrasting diagnostic methods for this phenomenon are thermographic investigations capable of determining the temperature of a surface through the measurement of emitted infrared radiation and diagnosing rising dampness issues. Thermography also constitutes a valid means for investigating and identifying thermal bridges that can exacerbate the phenomenon of rising dampness, for which the use of a thermal bridge calculation software can be useful for careful planning aimed at minimizing the impact of thermal bridges already in the design phase.

Consequences of Rising Damp

Rising dampness brings with it a series of problems that can have a significant impact on habitability and structural stability.
In general, the main consequences caused by the phenomenon are:

  • long-term structural damage: water infiltration can cause significant damage to foundation structures and can compromise the strength of building materials over time, leading to cracking, deformations, and, in severe cases, loss of structural integrity. To verify the stability of structures, it is useful to rely on and use specific software for checks on existing buildings;
  • esthetic damage: presence of stains, halos, flaking, and bulges of plaster, paint, or wallpaper, salt efflorescence, and appearance of mold;
  • hygrothermal problems: thermal fluctuations caused by moisture can affect the thermal comfort of indoor environments. These hygrothermal problems, caused mainly by temperature fluctuations due to moisture, can make environments less comfortable and contribute to the deterioration of living conditions.

The presence of moisture in foundations not only poses a threat to the structural and thermal stability of the building but also leads to a series of related health and economic risks and problems, including:

  • unhealthiness: moisture promotes the formation of mold and fungi, creating an unhealthy environment that can cause a range of health problems (colds, sinusitis, sore throats, arthritis, rheumatism, allergies) and worsen pre-existing conditions;
  • increase in costs and loss of property value: the insulating properties of damp walls decrease, making both heating and cooling the house more expensive. Furthermore, furniture, upholstery, accessories, and coverings are subject to damage, and continuous maintenance work is often necessary to try to hide the problem.

How to Eliminate Rising Damp: Remedies

The field of building restoration offers various remedies to effectively solve rising dampness, including:

  • mechanical interventions;
  • chemical interventions;
  • electrosmotic interventions;
  • evaporative plasters.

One of the most common techniques is the use of chemical barriers, obtained by injecting special resins into the masonry. This process involves continuous drilling of the wall horizontally to create a barrier against moisture. However, this solution may not always be effective if the masonry is excessively damp or if the injected liquid disperses, compromising the formation of a uniform barrier.
Another strategy involves the use of aeration and drainage systems to promote complete water drainage from the affected area. Subsequently, once the wall begins to dry, it is possible to apply a special plaster to prevent future moisture problems.

Among the more accessible solutions is the injection of silicone-based substances into the masonry, which seal the capillaries preventing the rise of moisture.

Another alternative involves the use of electro-osmosis and polarity reversal, which requires the installation of specific devices to redirect water into the ground through the application of an electric field opposite to the natural one. This method requires the installation of electrodes along the wall and may require time for complete wall drying.

In general, it is advisable to combine remediation interventions with the application of a macro-porous plaster, capable of promoting moisture evaporation within the masonry. However, it is important to note that this intervention alone may not completely solve the problem of rising dampness.

How to Prevent Rising Damp

To prevent rising dampness, it is essential to intervene under the floor with the application of a screed and the installation of specific membranes, along with the use of pumps to ensure proper drainage of excess water below the building. However, this intervention alone may not be sufficient and it is important to integrate it with adequate thermal insulation.
Furthermore, proper building maintenance is always advisable, therefore I suggest using maintenance management tools to optimize times and reduce costs that may arise from unwanted events.

Difference Between Condensation and Rising Dampness

When addressing the issue of rising dampness, it is essential to distinguish this phenomenon from condensation, which represents a different issue with specific solutions.
Condensation moisture mainly forms in indoor environments with high amounts of water vapor, such as kitchens and bathrooms. This phenomenon occurs when moisture in the air condenses on surfaces, causing moisture accumulations especially during colder months. In more severe cases, it may be necessary to identify and resolve thermal bridges in the building with the help of maintenance management tools that allow you to analyze finite elements and assess the risk of mold formation.

Furthermore, to verify the risk of interstitial condensation, it is essential to accurately calculate the thermal transmittance. Therefore, make sure to use specific tools for calculating thermal transmittance that allow you to determine real-time thermal transmittance and assess the risk of interstitial condensation through the Glaser diagram.

On the other hand, rising dampness is distinguished from condensation because it manifests with uniform stains along the walls, moving from bottom to top. The patches caused by capillary rising dampness are clearly visible and usually do not exceed one meter in height. These stains do not disappear over time, as they result from the presence of water inside the walls and do not dry easily.

 

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