Magnetic DPCs are the latest technical development in damp proof course (DPC) technology.
Magnetic DPCs appeared first during the 1980s in a need to address the shortcomings of previous DPC technologies. New scientific discoveries about Earth's energetic background, as well as advancements in antenna, radar and telecommunications technology paired with some clever practical electronic engineering resulted in a completely non-invasive solution, offering a permanent, efficient handling of rising damp.
They have nothing to do with magnets. They have been named after "magnetic fields" as these systems override or cancel out certain electro/magnetic fields in the building, responsible for the existence of rising damp. This concept is explained later in this section.
Evolution & History of DPC Technologies
The problems caused by rising damp have been documented in the UK since early Victorian times for almost 200 years, as a result various damp proof course (DPC) solutions have been devised to deal with the problem.
The technology of damp proof courses has constantly evolved. During Victorian times they used solid DPCs made of slate, vitrified bricks or lead sheets. After WW2 chemical injections became the new thing. In the 1970-80s electro-osmotic DPCs have been invented, then from the 1980s onward various electromagnetic or "wireless" DPC solutions have also been added to the list of available DPC technologies.
Each DPC technology was a natural evolution over its predecessors, attempting to improve and simplify the process, while also addressing the shortcomings of previous generations. Thus we have:
- Original solid DPCs were an attempt to solve the problem of capillary rise, when most buildings were built onto the soil, which after a few decades or centuries resulted in fabric decay, health issues etc.
- Retrofit solid DPCs made of steel plates or impervious bricks were the first attempt to repair aged, decayed DPCs that reached their end of life. This was a challenging task as retrofitting a DPC was an invasive and very labor intensive task.
- Chemical injections: technical advancements in chemistry made the retrofitting process simpler and less invasive by reducing the workmanship to a few holes placed every few inches. Nevertheless, the injection process was still fairly invasive while giving variable results.
- Electro-osmotic DPCs: technical research into molecular phenomena and a better understanding of electrokinetic phenomena made possible a newer, smarter, less invasive approach, by applying a small voltage to the walls through some embedded wires. But it was not all perfect, the main reasons why electro-osmotic DPCs failed over time were the corrosion or physical damage to the wires, and more importantly, later findings have shown that in high salinity environments (e.g. old, porous, salt-laden walls) electro-chemical effects rendered the system ineffective.
- Magnetic DPCs: appeared first during the 1980s and attempted to address the shortcomings of electro-osmotic DPCs. New discoveries about Earth's energetic background, as well as advancements in radar and telecommunications technology paired with some clever practical electronic engineering resulted in the elimination of the trouble-prone wires - providing a truly contactless, non-invasive and hassle-free solution to rising damp.
More information about the role, history and importance of damp proof courses in a building can be found here.
In order to understand how it is technically possible for an electronic circuit to affect remote wall structures located several meters away, we have to understand some basic concepts about Earth's electric environment and how this affects the movement of water.
Understanding Earth's Global Electric Environment
As our buildings are built onto the ground, in direct contact with the soil, they become part of Earth's natural energetic ecosystem, known as Earth's Global Electric Circuit.
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).
Lightning, electrostatic storm charging and several other mechanisms also result in significant ground charges.
In addition, water flowing through sand, gravel and different soil layers containing mineral salts that possess an electrochemical charge, generates measurable electrical currents on the surface of the ground. Even slow water seepage - water currents travelling at very low speeds of just a few meters per hour (e.g. water table variations during and after rain) - can generate on the surface measurable electrical voltages and currents, known as spontaneous potentials. Larger, faster water streams are accompanied by more significant electrical and magnetic effects.
Near the surface, these currents also flow into the building fabric, generating electric fields inside the walls, contributing to the electro-osmotic pumping effect in the capillaries that pumps water up the walls.
Basic Working Principle
These findings about Earth's electricity open the door to new technological remedies.
If rising damp is created and driven by various electrical and magnetic effects from the environment, magnetic DPCs solve the problem of rising damp from energetical standpoint. They override or cancel out (filter out) those electro/magnetic fields from the immediate vicinity of the building that create rising damp in the first place. Once the primary cause is gone, the osmotic pumping effect inside the capillaries stops, resulting in the cancellation of rising damp in the building. The building stays rising-damp-free as long as the magnetic DPC system is kept in the building.
Magnetic DPCs come in two versions: active or passive systems.
1. Active Systems
Active systems are powered from the mains. They consist of a wall mounted signal generator or oscillator. This outputs a combination of frequencies which OVERRIDE the capillary effect in the walls, breaking the bond between the wall and water molecules. The required energy to achieve this is very small, so there should be no safety concerns here.
2. Passive Systems
Passive systems take a reverse approach. They don't output or emit anything, but instead CANCEL OUT (filter out) from the immediate area of the building those wavelengths that create rising damp. Suppressing or reducing these frequencies results in the reduction / nullification of the osmotic pumping effect, leading to the cancellation of rising damp in the building.
Passive systems are technically more sophisticated. They have the added benefit that they can work in buildings with no power supply (e.g. basements, to-be-converted barns etc.)
A more detailed technical description of our passive magnetic systems is given in the next section.
Magnetic DPC Patents
Doing a search on Google Patents reveals a good number of magnetic DPC patents - both passive and active - going back several decades. Most development comes from Europe, with no development track record from the UK.
We have listed some of them here in chronological order (click on each title to expand its content):
This US invention from 1980 presents two passive (unpowered) resonant circuits, each of them comprised of a spirally wound flat coil (inductance) connected to a capacitor located in the center of each coil. The two flat coils [1, 11] are mounted perpendicularly to each other, all housed in a plastic boxlike container.
The energy of the apparatus is supplied from outside by the abnormally high electrical and magnetic fields (interference of stray fields) always present in areas of rising damp. This energy drives the two oscillatory resonant circuits, which according to Lenz's law - an induced current in a circuit opposes the cause that generates it - create a local electromagnetic field opposite (180° out-of-phase) to to the incoming field that generates the capillary rise, reducing its effects - resulting in the dehydration of the building over the entire area of action of the device.
This French invention from 1988 describes two parallel oscillating circuits made of 4 spiral inductors, 4 capacitors and 4 rigid dipole antennas, mounted on insulating supports - the whole device being housed in a protective box permeable to electromagnetic fields. The unit also features an energy discharge circuit that can periodically discharge the accumulated energy of the oscillating circuits to the ground.
The device collects electromagnetic energy from the environment. its oscillating circuits create a reverse-phased field to the incoming field, which results in the cancellation of the osmotic pumping effect inside the wall capillaries. In addition, when the incoming electromagnetic fields are intense, some of the energy is discharged to an earth connection.
This German patent from 1989 describes a non-invasive powered wall dehydration system composed of a pulse generator  and a passive LC oscillating circuit (resonator)  which is connected to an antenna, that emits low-powered electromagnetic pulses to break the capillary bond between the wall fabric and water molecules. According to the author, the range of the device is about 20 meters.
This German patent from 2005 describes a powered device consisting of a flat Tesla coil placed in the vicinity of a damp wall (without touching it). The application of a high-frequency weak pulsed electrical field that breaks the attraction between the capillaries and water molecules, results in the water falling back into the ground under the effect of gravity.
This French patent from 2008 is composed of 3 independent inductance-capacitance oscillator circuits for neutralizing electromagnetic wavelengths of telluric (Earth) origin in the VHF, UHF and microwave bands (30 MHz - 3 GHz). This invention is an improved version of a patent from 1988 from the same author, providing wider bandwidth and simpler construction.
This French patent from 2009 describes a passive (no power required) resonator type device, comprised of a set of electrical circuits, each of them made of a number of circular conductive concentric rings with opposite openings for the reception of telluric waves.
According to Lenz's law - an induced current in a circuit opposes the cause that generates it - these rings create a local electromagnetic field opposite (180° out-of-phase) to the disturbed terrestrial electromagnetic field, cancelling its action over the entire area of action of the device, which is about 10-30 m depending on the number and configuration of conductive rings used.
According to the author, old damp walls become dry within 6-18 months, after which the walls are protected from any capillary rise during the entire operating life of the device.
For wide scale adoption, technical research must satisfactorily answer the following two important questions:
- The technical description and working principle of the DPC units: this has been done to a greater or lesser extent by various patents (a handful of them presented above).
- The mechanism of wall dehydration: based on our knowledge, this question has not been in the past satisfactorily explained, impacting the wide-scale adoption of this technology.
Observing small scale (nano- to micrometer scale) phenomena in capillaries is almost impossible. In addition, some molecular interactions in damp brickwork are incredibly complex - some aspects of how water behaves along surface layers are still not fully understood today.
With our in-house research into the nature and drivers of rising damp, we hope we can answer this question in much more detail - we have already made some very significant discoveries in this regard.
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