What is a Magnetic DPC?
A magnetic damp proof course (or magnetic DPC) is the latest technical development in solving rising damp non-invasively, based on the latest research about the mechanism of rising damp and electromagnetic phenomena affecting a damp masonry.
The Hygro-Thermal-Electromagnetic Environment
It is well-known that the moisture content of old walls is affected by ambient humidity and temperature changes (sunshine, heating, wind, rain etc.) – known as the hygro-thermal environment.
Recent research has uncovered a third important variable - the surrounding electromagnetic environment - which is also significantly affecting the movement and bonding of moisture to porous materials. The effect of EM fields onto water are well known in other areas of science, however in the field of architecture and building conservation this is a brand-new concept.
The Effect of the Electromagnetic Environment
To research the effect of the surrounding EM environment onto water, we devised the following setup: in the lab we have subjected two bricks – one with considerable salinity, the other one without any salt contamination – to periodic vapour wetting from an ultrasonic humidifier. 30 mins misting was followed by 90 mins wait, resulting in repeating two-hour cycles, 24/7 for several weeks. The logic behind the experiment was that water vapours, being the lightest form of water, are the easiest to be influenced by electromagnetic fields.
Using a professional 80-channel Tektronix data logger we have collected a multitude of parameters from each brick: temperature and humidity readings from the surface and depth, magnetic field readings as well as many electrical parameters.
Daily Periodic Variations – Day vs Night Humidity
Despite of the fact that the temperature and the wetting cycles from the humidifier were kept uniform throughout each wetting cycle, the moisture content of the bricks displayed periodic variations, increasing during the daytime and decreasing during the night.
We found that these periodic daily variations were in sync with the daily rotation of Earth around its axes and its relative position to the Sun. The Sun, in addition to light and heat, is also a source of electromagnetic (EM) fields. EM fields charge up the wall fabric, resulting in a stronger daytime bonding of water molecules to capillary surfaces.
During the night the opposite happens: the mass of the planet shields us from the Sun, resulting in less EM electromagnetic fields, less charge-up of the wall fabric, less capillary bonding, more evaporation, resulting in a drier wall fabric.
Monthly Variations – Full Moon vs New Moon Humidity
In addition to daily variations, we have also observed recurring monthly variations: during certain days of the month humidity levels went up significantly, while during others they came down.
These variations seem to coincide with Earth’s relative position to the Moon; humidity levels being at their monthly highest during Full Moon, and at their lowest during New Moon.
Around New Moon the wall fabric becomes the driest. During Full Moon the opposite happens, the fabric retains more moisture than usual, becoming the dampest (considering all other variables stay the same).
We can see that the external EM environment impacts the movement and retention of moisture inside the wall fabric.
Wetting Mechanism – Moisture Barriers
Walls retain moisture because of the existence of moisture barriers.
There are two types of moisture barriers:
- Physical barriers: any non-breathable material that hinders evaporation (e.g. cementitious plasters, plastic membranes etc.)
- Energy barriers: a less known fact is that the movement of moisture can also be blocked by the presence of electrical potentials inside the wall fabric, these acting as energy barriers.
For example, every time when a solid object comes in contact with water (either in liquid or vapour form), an energy barrier appears on the solid surface as a result of the electro-chemical interaction between the two materials. This energy attracts and bonds water molecules to capillary surfaces, starting the wetting process.
It is important to stress that this energy barrier – also known as the electrical double layer (EDL) – is natively present in all breathable materials, so the entrapment of water also occurs in perfectly breathable materials.
The presence of salts in the masonry can significantly strengthen the electrical double layer. Salt ions being much larger in size than water molecules, make the energy barrier stronger, increasing the wall’s ability to trap and hold onto moisture. This is known as the hygroscopic effect of salts, and it's an electrical moisture retention mechanism.
Moisture barriers reduce a wall’s breathability – it’s ability to let go of the moisture and dry out.
Here are some comparative figures on how various factors contribute to the bonding of water to capillary surfaces:
- Free vapours in the air [orange band]: have the most mobility. Between successive wetting cycles the moisture content of in the air varied between 65-96%, a 31% change. We can also observe the day-nightly variations of the moisture levels due to the rotation of the Earth.
- Wall surface [light blue band]: the mere proximity of wall surfaces reduces the movement and evaporation potential of moisture by a third (to 20%, 68-88%) – the effect of the EDL as an energy barrier on a breathable wall surface.
- Wall depth [dark blue band]: in depth the ability of moisture to evaporate is further reduced by another third (to 10%, 72 – 82%)
- Salts in depth [dark green band]: finally, the presence of hygroscopic salts in the fabric reduces the moisture’s ability to evaporate by a factor 5X, to a mere 2% (76-78%). This is a 15X overall reduction in breathability compared to the vapours in the air (2% vs 31% change – green vs orange bands).
As we can see, the presence of wall surfaces and salts significantly affects the ability of moisture to evaporate from a breathable wall fabric, also affecting the wall’s ability to naturally dry out.
These research figures give us a glimpse into the power and effect of energy barriers onto the evaporation of moisture – and these findings describe the behaviour of a highly breathable masonry without any physical energy barriers present.
The presence of any non-breathable materials (physical barriers) further compounds the problem, speeding up the moisture accumulation under the surface, making dampness problems much more severe.
The removal of non-breathable materials is important, as this allows a good amount of moisture to evaporate and the wall fabric to become drier. This, in many instances, brings about a significant improvement. However, when the wall fabric is salty – in case of farm/barn conversions, rising damp situation, old churches and chapels, buildings close to the sea etc. – breathability can only be regarded as a partial solution where the surface mostly dries out, but under the surface the wall fabric stays significantly damper – the moisture being held in the fabric by the energy barriers described above.
These findings explain why a wall fabric can dry out relatively easily after rain (intermittent wetting with little/no salts involved), and not dry out or keep deteriorating when rising damp is present (continuous wetting from the soil with no breaks, often lots of salts present).
Drying Out the Wall Fabric
What can be done to further improve the breathability of the wall fabric or to decrease the moisture trapping effect of the energy barriers inside the building fabric?
Being electrical in nature, the properties of the electrical double layer (and its ability to attract and retain moisture) can also be altered by changes in the ambient electromagnetic environment – some changes would increase, others decrease the adhesion of water to capillary surfaces.
The magnetic damp proof course (DPC) is a non-invasive green technology that slightly alters the electromagnetic environment in/around a building in a way to decrease the adhesion of water molecules to capillary surfaces thus also improving the breathability of the building.
The construction and working principle of the magnetic DPC system is described in detail on the next page, however these simple fundamentals also must be understood.
Additional Research Data
For those interested in more scientific research data, here are some additional findings
Moisture Accumulation vs Evaporation
During the initial wetting of a completely dry masonry we can identify two distinct phases:
- Moisture accumulation phase: when moisture first makes contact with a dry masonry, it starts accumulating inside the fabric. The incoming humidity is trapped by the electrical double layer (energy barrier) and the moisture content of the masonry in depth is steadily rising (blue line). During moisture accumulation the surface evaporation is non-existent, the moisture content of the surface (green line) stays at the same level as ambient humidity (pink line).
- Evaporation phase: once capillaries get filled with vapours a saturation point is reached. The masonry can’t take any more moisture.
These two distinct phases are shown on the chart below.
We can see that surface evaporation will not start (green line, surface humidity sensor) until the depth humidity (blue line) has reached 100% RH.
Magnetic Field Variations
As shown earlier, the surrounding electromagnetic (EM) environment is affecting the bonding and retention of moisture inside the capillaries.
For e.g. the variation of external magnetic fields can be visualized with magnetometers. Looking at Earth’s magnetic field, in addition to the regular slow changes we can also observe periods of very fast changes which carry a considerable amount of energy. These fast variations are known as geomagnetic pulsations, and they are fast variations of Earth's natural magnetic field.
The geomagnetic pulsations (orange) penetrate the walls, transferring their energy to the wall fabric, generating fast-changing voltages (red) and currents (blue) inside the wall fabric. Although geomagnetic pulsations are relatively small (about 1-2 nT), their effect onto the even tinier water molecules (about 0.1 nm) is significant.
The induced currents in the wall fabric, having very sharp fronts, injecting energy into the electrical double layer (EDL), charging-up the capillary surfaces. This increases the EDL’s ability to bond and retain much more water molecules than in a less charged state, keeping the masonry damper.
Because geomagnetic pulsations originate from the Sun – which in addition to light, heat, UV rays etc. also emits magnetic energy – their charging effect on the EDL is going to be much stronger during the daytime than during night time.
This results in a stronger bonding of water molecules to capillary surfaces during daytime and less bonding during night time. This explains the gradual increase of humidity levels during the day and their gradual decrease during the night – most significant changes being visible in the depth of the fabric (dark blue line) as opposed to the surface (light blue line).
Electrical Phenomena vs Humidity Changes
Finally, humidity variations (blue) go hand-in-hand with electrical voltage or current (gold) variations in the wall fabric, as shown below.
Wall voltages (red) in an old damp wall also follow both depth (thick blue) and surface humidity (thin blue) variations closely, showing a strong interdependence between them.
The cause-effect relationship between the main variables of the problem are summarized in the flow chart below. Changes of the ambient electromagnetic environment causes electrical variations inside the masonry; this interferes with the electrical double layer, affecting the bonding of water molecules inside the capillaries.
The reason why these effects have not been detected in damp walls sooner it can be attributed to a combination of several factors:
- Multidisciplinary knowledge: in order for someone to look for and find this data, in addition to architectural and building knowledge, must also be very familiar with Electronics and geomagnetic phenomena, having a thorough understanding of several seemingly unrelated disciplines.
- Sensitive instrumentation: while basic detection of some of these signals can be done with hobby grade multimeters, for accurate mapping and in-depth understanding of the variables, expensive professional measurement instrumentation is necessary.
- The data only become visible at fast data sampling: most building-monitoring focuses on long-term trends, taking readings at 5-60 minute long intervals. The magnetic pulsations described above are very fast, short, transient phenomena which can only be detected with very fast measurements; at slow data sampling rates these transient pulses remain undetected.
Without the ongoing daytime re-charging of the wall fabric, the walls would most likely discharge themselves through the ground, reducing the moisture-holding effect of the EDL as an energy barrier, allowing water to easily evaporate from the capillaries, resulting in a much drier fabric.
The magnetic DPC system reduces the charging effect of the electromagnetic environment, allowing the wall fabric to discharge itself and thus to get rid of most moisture trapped by the energy barriers.