Rising damp is the natural upward movement of water inside porous masonry.
A Standalone Phenomenon
Rising damp is a STANDALONE phenomenon that can occur on its own on both internal or external walls, even in well-maintained buildings, independent of any other dampness problems or building defects.
Rising damp is NOT CAUSED by various building defects or lack of proper maintenance (such as a bridged damp proof course, the use of cement plasters, non-breathable materials, improper pointing, higher ground levels, lack of heating etc.) – although such problems, by creating their own set of dampness issues, interfere with the dynamics of rising damp, often “amplifying” its symptoms, making it worse or bringing it into view.
Fixing any of these defects, if they exist, will improve the building; but rising damp - if unaddressed on its own - stays there and will create problems (years) later.
A very important but often less known or neglected aspect of rising damp are ground salts. The rising water flow draws up diluted salts from the ground, depositing them into the building fabric. Following the evaporation of water, salts crystallize, expanding 5-10 times in volume. The exerted mechanical expansion pressure (crystallization pressure) leads to the cracking, crumbling and flaking of the plaster and wall fabric – a combination of symptoms commonly known as rising damp.
Here are some examples of rising damp from old buildings, many of them perfectly well maintained with no other problems.
Electrical Charges in the Ground
Our buildings are built onto the ground, in direct contact with the soil, and as such an integral part of Earth's global electric ecosystem, known as Earth's Global Electric Circuit.
Our planet receives most of its energy from the Sun. The variable intensity solar wind keeps hammering Earth's magnetic field (the geo-magnetic field) creating smaller or larger variations in he upper atmosphere known as the ionosphere.
These magnetic variations cascade down to the ground, where they induce electric currents both near the surface (known as geomagnetically induced currents or GICs) and the deep underground (known as telluric currents, which literally mean earth currents). In addition, lightning, electrostatic storm charging and several other mechanisms also result in significant ground charges.
The effects of these earth currents are well documented in the scientific literature. It is well known that geomagnetically induced currents (GICs) can carry significant electrical charges through the soil and thus they can cause serious damage to the electric grid by overloading, overheating high voltage transformers to the point of collapse, causing blackouts) They can also affect underground pipelines by speeding up the corrosion of the pipes, resulting in a shorter service life.
Near the surface, these currents also flow into the building fabric, generating electric fields inside the wall, contributing to the electro-osmotic pumping effect in the capillaries that pumps water up the walls. The simplified mechanism of this is described next.
Capillary Pumping Mechanism
The wall fabric of old buildings - being built onto the soil at the soil-air interface - is affected by a number of electro / magnetic influences originating from both the soil and the air:
- Magnetic field variations [in the air]: which can be both natural or man-made. Variations in Earth's magnetic field are primarily caused by the variable intensity solar wind, creating larger or smaller magnetic variations, known as geomagnetic storms, substorms and magnetic pulsations.
Moving cars (traffic) or machinery intersecting Earth's magnetic field can also create significant magnetic variations near the surface. All these magnetic variations can be measured with magnetometers.
- Geomagnetically induced currents (GIC) [in the soil]: according to Faraday's law of induction a changing magnetic field induces an electric current in a conductor.
In case of Earth: the variations of the geomagnetic field described above- especially rapidly changing fields - can induce large electric currents in the conductive ground. These are powerful, extremely low frequency [0.001 Hz - 5 Hz] currents that can travel vast distances (hundreds or thousands of miles) without being significantly attenuated. These currents can be measured with ground electrodes.
- Man-made electromagnetic fields [in the air & soil]: with the explosive growth of telecommunications during the past 20 years (3G, 4G, 5G, WiFi, always-on-connectivity etc.) our buildings are more and more engulfed in electromagnetic pollution also known as "electrosmog". This can be regarded as an "electromagnetic climate change" which affects the fabric of our (old) buildings and the movement of water inside the capillaries.
Here is a simplified schematic of a wall built on the soil with an expanded view of a capillary showing the various electromagnetic forces influencing it.
Where the water and the capillary surfaces meet, a few nanometer thin transition layer is formed, known as the electrical double layer (EDL). In this thin layer various molecular forces are responsible for the adhesion of water to capillaries. This adhesion is of electrostatic nature.
The water column inside the capillaries contains diluted salts from the ground, making the water column in the walls electrically conductive. As a result, the conductive capillaries act as (millions of) tiny antennas (aerials), all susceptible to electromagnetic influences from the environment.
Changing electromagnetic fields in the environment (both natural and man-made, as shown above) induce an electrical voltage and field (E) inside the conductive water, creating an electroosmotic flow or electroosmotic pumping effect inside the capillaries, which starts, stops or varies based on the intensity of external fields.
The induced electroosmotic flow opposes and overrides gravity, pumping water up inside the capillaries. This is the fundamental mechanism of rising damp.
These induced voltages and currents in the masonry are indeed present. They can be measured in any damp wall with a good quality multimeter.
The voltages and currents rise and fall in time, as driven by external factors, as shown below by our in-house lab experiments. Typical voltages are in the 100-500 mV range, typical currents in the nano ampere (nA) to micro ampere (µA) range.
Solving Rising Damp
Rising damp is typically tackled by builders by installing a damp proof course, which in most cases is a chemical DPC. In listed buildings or conservation areas, where invasive solutions are not an option nor desired, the possible remedies typically include:
- Replastering with lime
- Improving the drainage, ventilation and heating
While these solutions often create a positive change, none of them solves rising damp long term.
For a long-term solution the electromagnetic aspect also needs to be known and addressed, otherwise - with them acting in the background - the problem will return within a few years.
To reduce or nullify the effect of external fields responsible for driving the water up, those need to be somehow collected and absorbed, so their effect can be canceled. One way of doing this is by using a compact antenna or aerial system. Antennas are commonly used to collect electromagnetic signals, usually TV and radio signals.
A wide-band aerial system - placed in a protective case, specifically designed to filter out those specific frequencies that are known to drive rising damp the most - can be installed in the building, to collect and absorb the offending frequencies, acting as a bypass circuit, channeling the electromagnetic wavelength away from the walls. Without the electrical drivers the electroosmotic pumping effect stops, the water from the capillaries flows back into the ground and the walls gradually dry out.
Utilizing a receiving antenna, which only collects energy from the airwaves without emitting out anything, such a system does not create electromagnetic pollution (in fact, it reduces it by absorbing some of it), so it does not have any health-related side-effects nor affect WiFi or household electronics.
Magnetic damp proof courses, the newest development in dealing with rising damp non-invasively, utilize this exact principle.
- Rising damp is a standalone phenomenon that can occur in any well-maintained old building. It is not caused by various building defects or lack of maintenance, however other problems creating their own set of dampness issues, overlaps rising damp resulting in a combined problem.
- Fixing any such building defects (drainage, pointing and plastering, ventilation, water ingress etc.) will improve the overall situation, but rising damp needs to be addressed on its own.
- Houses are built onto the ground, thus they become part of Earth's global electrical environment.
- The soil and the surrounding air contains significant electrical charges, that drive / heavily influence the movement of water in the masonry by inducing electro-osmotic flows in the capillaries. Capillary attraction is also an electrostatic phenomenon, hence it can easily be influenced by other electro-magnetic processes.
- Collecting and cancelling out certain electro-magnetic influences from the surroundings of a building stops the fundamental cause of rising damp, solving the problem permanently and non-invasively.
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