Magnetic Damp Proof Course

Non-invasive Rising Damp Remedy

In this section

Key Features

Here are some key features of this product.

Green Technology

Building-friendly, eco-friendly technology.

Improves the Walls' Breathability

The application of this product improves the breathability of the wall fabric.

Non-Invasive

This product does not damage the underlaying wall fabric.

Extremely long lasting

As it contains no moving parts, it is extremely robust and long-lasting. 

Suitable for Listed buildings

This technology is suitable for historic or listed buildings.  

Magnetic Damp Proof Course - Description

There are two main ways of preventing the rise and accumulation of moisture in the wall fabric:

  1. Inserting a physical moisture barrier in the walls (e.g. slate, membrane, chemicals etc.) to physically block the rise of moisture. This technology, in various forms, has been around since Victorian times, for over 150 years. Today, all new buildings are fitted a physical DPC, however retrofitting a DPC in an old building is challenging due to the invasive nature of the intervention.
  2. Improving the breathability of the wall fabric to the point that moisture can freely evaporate out of the capillaries instead of being trapped by them. If the evaporation rate of the wall fabric is higher than its moisture intake rate, the wall dries out even if no physical DPC is present.

The magnetic DPC is employing this second principle.

What is a Magnetic DPC?

A magnetic damp proof course (or magnetic DPC) is the latest technology that can solve the problem of rising damp by improving the breathability of the wall fabric to the point that most moisture evaporates out of the wall fabric and it becomes dry. It is a sympathetic, building-friendly, innovative technology suitable for all buildings, including listed buildings.

The magnetic DPC does not attempt to block the movement of moisture, but on the contrary: it makes it possible to very easily escape from the wall fabric by reducing the bonding power of water vapours to capillary surfaces. Less bonding = more evaporation = drier wall fabric. The magnetic DPC assists evaporation and makes the wall fabric more breathable.

Easiest way of understanding the concept is by watching this video, which explains in plain English the technical fundamentals of what is rising damp is, the factors that determine breathabilty (vapour permeability) and the research trail that led to the formulation of the magnetic DPC.

Working Principle - Simple Explanation

Moisture bonds to solid surfaces due to the presence of surface charges (also known as surface energies or adhesion forces). These are small electric charges present on all solid surfaces and attract small particles - such as dust or water vapour molecules. These electric charges are the primary mechanism behind the accumulation of moisture and wetting of the wall fabric.

The magnetic DPC reduces the adhesion forces between the water molecules and capillary surfaces, allowing the moisture to evaporate much easier. This improved breathability results in less moisture in the wall fabric, leading to drier walls.

The bonding of moisture is caused by electro-chemical charges

Working Principle - A More Detailed Explanation

Breathability is a very important concept in building conservation. It is a practical tool to manage the moisture content of old buildings. Keeping the wall fabric breathable allows the excess moisture to evaporate from the wall fabric.

Regarding breathability, it is generally believed that:

  • A breathable wall fabric stays dry as it can fully evaporate out all its moisture content and doesn't trap any moisture.
  • Moisture accumulation is caused by the presence of moisture barriers: non-breathable materials (e.g. cement. plastics) applied on the surface.
  • If the moisture barriers are removed and the breathability of the masonry is restored, the wall fabric dries out and stays dry thereafter because it can now breathe.
It is assumed that vapours just 'fly through' a breathable wall fabric
It is also assumed that moisture accumulation is caused by vapour barriers

These statements assume that a breathable wall fabric does not interfere with the passage of vapours - those just "fly through" the fabric without affecting it, meaning if 100% moisture goes into the fabric all 100% comes out on the other end, no moisture accumulation occurring in the fabric. 

Technical research, however, has conclusively demonstrated than none of the above assumptions are true.

In real life a breathable wall fabric does interfere with the water vapours and traps some moisture, which over time leads to moisture accumulation.

In real life, a breathble wall fabric accumulates moisture

Let's look at some basic research data to understand why.

In the lab we have built a small test wall from of "old-style" soft, porous, new bricks placed on drained damp soil. At the beginning of the experiment the bricks were completely dry. Then we removed the plastic foil from under the bricks allowing water vapours to move into the bricks. We have monitored the movement of moisture from the soil, through the bricks, to the surface with a large array of sensors, taking consecutive readings from all masonry areas and the environment.

Experimental setup with the drained soil, bricks and many moisture sensors.

Once the masonry has made contact with the damp soil - we noticed that the moisture build-up occurred in two distinct phases: 

  1. [Phase 1] Moisture accumulation: moisture started accumulating steadily inside, under the surface of a dry brick (blue line), reaching 100% RH in about 4 hours. During this time no evaporation took place through the surface, the surface humidity (flat green line) being low, matching the ambient humidity (pink line).   
  2. [Phase2] Evaporation: once the brick pores have filled up with vapours, the excess moisture started evaporating out, indicated by the steadily increasing surface humidity (green line).
surface-vs-depth2-core-conservation
Moisture accumulation in a dry breathable brick

This behaviour is caused by electrical surface charges (also known as surface energies or adhesion forces). These are small electric charges present on the surface of all solid materials which can attract light particles - e.g. dust to solid surfaces; or water vapour molecules to capillary surfaces. These charges attract and initially trap water vapours (Phase 1). Once the vapours have covered the capillaries with a thin water film, to some extent neutralizing the surface charges, subsequent water vapours can now fly through the capillaries, resurfacing on the other end, resulting in an evaporating flow (Phase 2).

These electric surface charges are the primary mechanism behind the accumulation of moisture and wetting of the wall fabric.

The low residual moisture content of the bricks in the lab is not a problem. However, a real wall outside of the lab, is constantly subject to multiple moisture sources from the environment. Perhaps, due to the presence of some rainwater, the fabric gets wet and the capillaries temporarily fill with water. This, near ground level, starts the upwards movement of salts. The accumulating salt ions lead to more electric charge accumulation in the fabric. As the masonry ages, its salts content increases and with that, the permanent surface charge of the masonry also increases. Salts attract more water, the water draws in more salts and a chain reaction starts in the lower part of the wall, in the so-called rising damp zone.

If, for any reason the masonry gets replastered with a cement plaster - as it often happens in real life - this speeds up the moisture accumulation tremendously. The moisture is the capillaries is now retained not only by the surface charges but also being blocked physically. Liquid moisture develops in the capillaries, carrying and spreading more salts. The accumulating crystallizing salts will eventually make the masonry crumble.

By this time many complex phenomena take place in the masonry, the explanation of which goes beyond the scope of this section. The point we are trying to make is that amidst all this, the fundamental bonding mechanism - the "glue" in the masonry - that bonds water to capillary surfaces and makes water accumulate are the electrical surface charges.

The fundamental bonding mechanism - the "glue" in the masonry - that bonds water to capillary surfaces and makes water accumulate are the electrical surface charges.

Reducing these surface charges, on the other hand, could reverse some of these processes. The evaporation of the masonry would increase, the liquid water from the capillaries would significantly diminish or disappear, leading to a drier masonry. This would stop the salt transport and salt accumulation, stopping or slowing down the ongoing crumbling and fabric decay, stabilizing the masonry.

Magnetic DPC - Operation

How could the surface charges in the masonry be decreased? Looking into the behaviour of surface charges, a series of experiments led to some important discoveries.

One key finding was that electric surface charges are affected by electromagnetic (EM) fields.

The EM environment is invisible to the human eye, but it can be visualized with magnetometers. Using high-end magnetometers which can detect very small changes of the magnetic field, we can observe that the magnetic variations in a room around the walls (orange) also shows up in the wall fabric in the form of small voltages (red) and currents (blue), these mirroring the surrounding magnetic fields very closely.

Although these magnetic variations in the room (orange) are relatively small (about 1-2 nT), they can create a substantial effect on the tiny water molecules of about 0.1 nm in diameter.

Magnetic changes in the air show up in the walls as voltages and currents

The fact that walls pick up EM energy from the  surrounding environment is not surprising as old masonry are surrounded swim in an "electromagnetic sea", being surrounded by energy. The longer term variation of currents in the wall fabric (blue) mirrors very closely the magnetic field variations from the air (orange), showing the cause-effect relationship between ambient magnetic fields and electrical effects in the masonry.

mag-vs-current-core-conservation
Electrical currents in the masonry (blue) follow closely magnetic field variations (orange)

What relationship has been found between the magnetic fields and electrical phenomena in masonry, and their effects:

  • Stronger magnetic fields in the environment cause higher surface charges resulting in a stronger bonding of water to capillary surfaces.
  • Weaker magnetic fields result  in lower surface charges, resulting in weaker bonding of water to capillary surfaces.

Decreasing or absorbing certain magnetic fields from the environment can decrease the electrical surface charges, resulting in weaker capillary bonding, better evaporation rate of moisture and ultimately drier walls.

The magnetic DPC system is an electromagnetic “drainage” system that absorbs certain EM fields from the building. Once installed, its internal circuitry absorbs some of the surrounding magnetic fields, diverting that energy away from the walls into the ground via an earthing connection.

Same as a pump that drains liquid water out the building, or a dehumidifier that drains the vapour moisture out of the room, the magnetic DPC system “drains” the room of some of its EM energy that "fuels" the bonding of water vapours to capillary surfaces. Less EM energy in the room leads to less surface charges and less vapour bonding, resulting in a drier masonry.

The energy collected by the magnetic DPC is sent to the ground

As a result, there is a constant energy flow from the DPC unit to the ground, the unit constantly "draining" the environment from its EM energy. The small decrease of the magnetic field in the building, in the active area of the unit, can be visualized with very sensitive magnetometers. Based on actual measurements the magnetic field decrease 5 metres away from the magnetic DPC unit is about 2.5 μT (micro Tesla) or 2,500 nT (nano Tesla), which is a very small amount.

magnetic-field-decrease-core-conservation
Magnetic field changes before and after the installation of the magnetic DPC unit

To put this value into perspective: here is some third-party data giving examples of typical magnetic field values from various applications:

  • A typical refrigerator magnet creates a magnetic field of about 5,000 μT (5 mT)
  • A pacemaker can be safely exposed to magnetic fields up to 500 μT 
  • Earth's "background" magnetic field varies between 30-70 μT, depending on latitude and location
  • The magnetic field caused by a shielded microwave oven 1 foot away is 4-8 μT
  • The magnetic field reduction caused by the magnetic DPC is about 2.5 μT

As shown above, the changes produced by a magnetic DPC unit are completely insignificant to the human body but very significant to the tiny vapour molecules in the walls (0.1 nm in size) which about 10 billion times smaller than the human body. Another comparative figure: 1 gram of water contains about 3.34 x 1022 (about 1 trillion x 10 billion) water molecules, so the behaviour of water vapours can be influenced by almost inconceivably small amounts of energy, of the right type.

The installation of the magnetic DPC results in allows the walls to reach a newer, drier state of equilibrium. It shifts the overall moisture transport pattern of the masonry in the direction of less liquid movement and more vapour movement, allowing the masonry to better breathe and reach lower and drier states of equilibrium which could not have been attained otherwise. Less liquid transport also results in less salt transport and accumulation, which from building conservation viewpoint is a very desirable outcome

The magnetic DPC  system can complement the removal of cement or other non-breathable materials and can improve the breathability of the fabric even when removal of other non-breathable materials would be unpractical, too intrusive or too costly.

Magnetic DPC - Internal Construction

The electromagnetic "drainage" of the masonry is achieved with the electronic circuitry of the magnetic DPC - a precision aerial system mounted in a protective case. The casing forms an integral part of the system, acting as a closed cavity resonator.

Inside the case there are a number of circuit boards with many spiral antennas etched onto them, each of them precisely tuned onto specific frequencies. These are responsible for absorbing certain EM fields known to influence the bonding of water to solid surfaces, while leaving other parts of the EM spectrum intact.

magnetic-dpc-construction-core-conservation
Internal construction of the magnetic DPC

Antennas (or aerials) are energy converters. They pick up electromagnetic (EM) energy from the environment and convert it to an electrical signal which is usually amplified or processed - just think of a TV or mobile phone.

The spiral antennas of the magnetic DPC system operate on the same principle. They pick up and convert the EM energy into electrical signals, which, instead of being amplified, are sent to the ground and discarded through the unit's earthing connection, bypassing the walls.

The active radius of DPC various units vary between 10-30 metres, depending on the size and type of unit, so in the majority of cases one single DPC unit covers the whole footprint of the building. The active range can be affected by the thickness and layout of the walls and the installation location of the unit in the building. Typically, they are installed on the ceiling of the ground floor in a service area (under stairs, hallway, pantry, utility room, cellar etc.) to keep them out of sight, but other installation locations can also be considered.

As the DPC units do not contain moving parts, they have an extremely long lifetime (several decades), the main limiting factor in terms of service life is the longevity of the internal circuitry, which can last for decades. These systems do not have running costs and do not need maintenance.

Being reception-only devices they  don't need a conventional power supply, only a good quality earthing connection. This allows the units to operate in buildings where the electrical supply is not yet operational (e.g. future barn conversions, ruins etc.)

The magnetic DPC system does not influence and creates no interference with any residential or commercial electronic or medical equipment or machinery.  

This tech has been around for a while, research lagged behind.

(see patents)

Safety

Nowadays the ever-increasing amount of electromagnetic (EM) radiation can be a cause of concern for some. This is because most telecommunication devices (such as mobile phones, Wi-Fi routers, smart appliances etc.) perform a dual function: they both receive and transmit EM waves. Because they transmit, they output a small EM radiation which can add up.

Zero EM Output, No Interference

It is important to understand that the magnetic DPC system, by design, only receives energy from the environment and does not transmit (outputs) anything. As such, it can't interfere with any telecommunication equipment from your household or workplace.

Here is the manufacturer's EC Declaration of Conformity, certifying that the system passes all relevant European Electromagnetic Compatibility (EMC) standards.

EC Declaration of Conformity

Moisture Reduction Effect

The dehydration effect of the magnetic DPC has been subject to extensive testing in various fabrics through embedded sensors by taking consecutive readings from the the depth and surface of masonry as well as from the surrounding environment – monitoring the movement of moisture in real time throughout the wall fabric.

Here are some photos of the experimental setup and some of the sensors used during the testing.

Here is the moisture content variation of the walls during the first 6 months, between November - April throughout a very rainy winter and spring, showing a consistent drop of the moisture content of the crypt walls.

Moisture reduction of the crypt walls during the winter months

Here are some additional research data and graphs about some of the changes observed in the crypt during the installation of a magnetic DPC system.

Here are some additional information showing the inter-dependency of magnetic fields, masonry surface charges and moisture content of the walls. 

Shortly after the installation of the magnetic DPC we can notice a drop in the surrounding magnetic field. The drop is about 2,500 nT (nano Tesla) or 2.5 μT (micro Tesla) - very significant to the 0.1 nm sized water molecules, but highly insignificant to an infinitely larger human body.

Changes in the ambient magnetic field (green) results in changes in the wall surface energy (red), resulting in increased moisture evaporation, leading to electrical charge movement and electrical current flow changes (orange) inside the wall fabric.

surface-charges1-core-conservation
Moisture reduction of the crypt walls during the winter months

The change in the magnetic field (green) and the increased vapour movement and evaporation leads to a gradual and consistent decrease in the moisture content of the wall fabric (blue) - measured by the embedded microwave sensor. The rate of the moisture change in this experimental setup amounted to about 0.1% by weight every 2 days - the equivalent of about 1.5% moisture decrease per month. This figure doesn't refer to relative humidity (RH) but to real liquid moisture content or absolute humidity change in relation to the weight of the material (% by weight).

moisture-drop-core-conservation
Moisture reduction of the crypt walls during the winter months

Composition

  • Aluminium casing: 99.8% pure aluminium. Paramagnetic (non-magnetic), permeable to magnetic fields.
  • Printed Circuit Boards (PCBs): fibreglass, copper, silver
  • Electronic components: various SMDs, capacitances, inductances
  • Mechanical components: selected materials with special electric and EM properties 
  • Paints, surface coatings: with special electric and EM properties

Technical Data

Resonance frequency (MHz)
1,420
Frequency range (MHz)
1- 2,500
Absorbed EM fields
2.5 μT
Emitted EM fields
None
Interference caused
None
System 1 — DELTA, PIRAMIS
-- Active radius (m)
10
-- Weight (kg)
1.6
-- Dimensions L x W x H (cm)
30 x 30 x 15
System 2 — MAYA
-- Active radius (m)
15
-- Weight (kg)
2.4
-- Dimensions L x W x H (cm)
30 x 30 x 30
System 3 — TURBO
-- Active radius (m)
25
-- Weight (kg)
5.1
-- Dimensions L x W x H (cm)
50 x 50 x 50

Awards & Nominations

This product has won / been nominated for the following awards:

More Information

Here are some related pages with additional technical information, giving you a more in-depth understanding of this topic.

Solutions

This material can be used in the following applications or solutions:

Videos

Here are some videos about the application and performance of this product. Please unmute the videos if there's no sound.

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Projects

Here are some of our projects where this product has been used:

Any Questions? Need Technical Advice?

If you have any questions about a project, a problem, a solution, or any of our plasters - please get in touch.

We understand that each project is unique. Using the contact form below feel free to ask us any question. Give us as much detail as you can about your project so we can get back to you with more relevant answers. 

Testimonials

Here are some client testimonials:

cottage

I had an ongoing and very persistent dampness problem in my 1860s flint and lime worker’s cottage. My builders and I had tried everything possible to remedy this, working within the restrictions of the age of the cottage and its building methods and materials.

Core Conservation came to inspect the problem very soon after contact. At the meeting they did undertake the analysis of the affected areas and explained to the builders and myself how their damp proofing system would work, which was installed shortly afterwards.

Despite a very wet winter I quickly saw a change in the damp areas, which seemed to be drying out quite rapidly. The damp proofing system was installed at the beginning of an extraordinarily wet period and the walls appear to now be more or less dry, six months later, which was confirmed by the 6 monthly follow-up testing. The team I have been working with has all been delightful and I commend their patience, politeness and spotless working procedures.

Susan F
cottage

We were recommended Core Conservation by some conservation professionals.

Following an initial consultation with an engineer, we installed the dehydration system into our Grade II listed Tudor cottage in October 2017. The Engineer returned only last week to evaluate changes to the severity of the rising damp in our walls since installation. After only 6 months there is a marked improvement in readings, some of which are 50% lower than those established at outset. We are very pleased with the findings and look forward to the next scheduled visit in 6 months’ time to learn of further improvement readings. Well done!

Kate S
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