1

A formal and comprehensive analytical case study on the

effectiveness of controlling rising dampness in buildings

using applied science and the PROsystem unit.

CASE STUDY

PROSYSTEM CONTROLING RISING DAMPNESS

Introduction

The Damp Proofing industry is a £200 Million commercial venture in the UK with

over 3,000 contractors and 6 major manufacturers of remedial products.

There has always been the problem of reoccurring dampness in the industry and

the chemical solutions currently offered have received much criticism from the

Royal Institute of Chartered Surveyors (RICS) with technical members even

questioning the effectiveness of the classical damp proofing materials and

techniques currently available. There has been further criticism from heritage

supporters suggesting that the cement and gypsum based plastering technically

endorsed by the industry traps moisture, and prevent substrates from breathing

naturally, itself creating further dampness issues.

The Damp Proofing Association (DPA) was requested by Damp Protection Ltd to

test the effectiveness of their product PROsystem in controlling vertical

transmission of moisture commonly referred to as rising damp. This document

provides the results and testing of the unit.

2

What is Rising Damp?

Rising damp is the common term for the slow upward transmission of moisture

molecules in the lower parts of property walls and other ground-supported

structures. It is an important cause of wetness in buildings and forms one of the

four elements of dampness along with condensation, penetrating and lateral

damp. It is a cause of decay, especially when in contact with timber structures,

and deterioration in standing stones, monuments and archaeological and

historical sites. Much has been written about rising damp, some informed and

some less so, it is probably the most misdiagnosed element in the entire building

industry, its detection should be limited to qualified individuals who will have

trained access to on site moisture analysis (quantitative), thermal imaging

cameras and moisture profiling devices to perform an accurate diagnosis of any

dampness issue.

Rising damp is a complicated process and much remains to be studied in more

detail, but we do now understand that the primary physical processes arise from

capillary forces at work within the pores of the materials. These forces are

responsible for the initial uptake of water from external sources, such as ground

water, driving rain or leaks, or through condensation. Lack or blocked sub floor

ventilation can substantially contribute to building dampness and often at the

lower parts of the structure that many unskilled Surveyors will term as rising

damp.

Capillarity is also the cause of moisture migration within the fabric, the

redistribution of water from place to place which is associated usually with the

local differences of water content. Eventually, water may leave the structure and

the only important means to do this is by evaporation (liquid water turning into

vapour). The liquid–vapour phase change may occur at a building surface or

inside the fabric to be followed by vapour migration within the material before

eventual entry into the atmosphere. These various processes all fall within the

scientific theory of unsaturated flow, the term emphasizing that the materials in

the building fabric are rarely fully saturated. If they were, capillary forces would

be absent and water movement could only occur in response to the external

forces. In practice, hydrostatic heads and gravity contribute to the overall rising

dampness equation.

The description of unsaturated flows can now be represented mathematically

with reasonable rigour. The mathematical models are often complicated and

frequently can be applied to particular cases only by means of computer-based

numerical methods. As a result, water transport modelling of building structures

linked to site survey and measurement is almost non-existent in building

conservation practice. But it is now technically possible and of course is

undertaken increasingly in the design analysis of heat, mass and air transfer for

new buildings carried out a brief but important exploratory analysis of water flux

in a standing stone at the Skara Brae archaeological site using numerical code

originally developed for modelling unsaturated flow in hydrology.

3

Fortunately, there is often a half-way house, where we can use simpler models,

which express the essential first-order features of the processes. This allows us

to avoid the use of numerical computation and highlights the important factors

and their physical interrelationships. There is a trade-off we obtain insight and

understanding, and reasonable estimates of the quantities we calculate, but less

detail than we obtain with numerical methods. In the field of unsaturated flow,

an important class of simplified models is based on sharp front (SF) theory.

Here, the important simplification is to ignore the rather fuzzy boundary between

wet and dry regions within a structure or fabric and to replace this by a notional

sharp boundary. We then ask how this boundary moves in particular materials

as water is fed into the structure from an external supply and perhaps removed

elsewhere by evaporation. These SF models are particularly good for dealing

with geometrical complications and with composite structures where two or more

different materials may be present.

PROsystem the Theory

PROsystem is an electronic control solution for rising dampness based essentially

on electro osmosis.

The theory of electro osmosis is covered in considerable detail in most text

books on physical or electro chemistry. A detailed treatment is beyond the scope

of this case study but the following outlines the principles and discusses the

factors influencing electro osmotic flow.

Electro osmosis is one of a group of effects known collectively as electrokinetic

phenomena. These are associated with the electrical charge frequently present

on the surfaces of two phases in contact with each other. The application of a

voltage (or electromotive Force) to such interfaces causes movement of the

phases in relation to each other. The movement of the two phases in relation to

each other produces the converse effect, i.e. the formation of a voltage. The

four electrokinetic effects can be simply stated as follows and motion caused by

applied voltage.

1. Electro Osmosis - Liquid caused to move through

a porous, static medium.

2. Electrophoresis - Solid particles caused to move

through a stationary liquid.

3. Streaming - Voltage produced by liquid Potential being forced through a

porous, static medium.

4. Sedimentation - Voltage produced by the Potential freefall of particles through

a liquid.

Of these 1 is the most important in the context of damp proofing, with the liquid

being the aqueous solution responsible for the dampness and the porous static medium being the wall. It is worth noting, however, that 2 electrophoresis, may contribute to damp proofing by moving particulate matter in the pores towards

the anode, producing blocking and a effecting capillary rise of water.

4

A streaming potential, 3, will also be produced during capillary flow of water

through the wall.

Physical Basis of Electro Osmosis

This represents a considerable over-simplification when compared to the real

situation at a surface, but is sufficient for present purposes, where the inner

charged layer can be regarded as fixed at the solid surface, while the outer

layer, which in practice is somewhat diffuse, can be regarded as mobile within

the solution.

If an electrical potential is applied across the ends of the pore, from an external

power source, the ions in the outer part of the double layer will move in a

direction dependent upon their charge and in so doing will cause the bulk of the

solution to move by exerting a viscous drag. Most solids acquire a negative

charge in moderately pure water, giving a positive charge in the outer layer.

The flow of water is thus generally in the direction of the cathode reversing the

rise of water molecules in wall structures often referred to as rising damp.

The PROsysten unit manufactured in four sizes

5

PROsystem Application pack

The Testing of PROsystem

The DPA technical manager supervised the testing of the PROsystem unit.

This case study has been compiled by the DPA. Neither the DPA nor the technical

manager has affiliations with our clients excluding discharging our duties in a completely independent and factual manner based on extensive experience and physical and chemical science.

No third party has attempted to influence this report and all parties having

cooperated completely throughout this process. Basis of providing professional evidence:

1. The information included within this report has academic support. The

technical manager studied Materials Technology at Hertfordshire University; with a final year research project and investigation into moisture diffusion in building products. This background is an ideal

technical foundation for the damp proofing industry. These professional qualifications should not be confused with “trade” qualifications such as

CSRT (non-University no entry qualifications required) that can be simply obtained by short term distance study.

2. The technical manager has undertaken over 20,000 surveys over the past 20 years in this specialist field; having produced technical reports for

courts, councils and dispute resolutions.

6

The PROystem unit has been tested in other countries but the manufactures

have requested an independent test in the UK to report and verify the

effectiveness of the system for controlling rising damp in buildings.

PROsystem approached a Church in Middlesex suffering from acute dampness,

the building is situated at close proximity to the river Thames and for reasons of

limiting unwanted visits we will not name the exact Church. The Church was

built in 1752 and the PROsystem unit was sited centrally. Before activating the

unit the DPA attended on 23/07/2014 and took 16 controlled measurements of

the comparative moisture content of the walls on all elevations along with all

associated thermal profiling.

The results are provided in the table below, but initially moisture readings were

within the range of 11% – 26 % with a strong profile of rising dampness. The

relative humidity was 65% on the day of the testing. There was visual evidence

of salt deposits and patches of dampness that can clearly be seen in the

photographs below.

The PROsystem unit was installed on 19/08/2014 and control initiated.

The DPA returned to the venue on 26/11/2014 and tested the same 16

measurement points and the moisture reading were all within the range of 2% -

6%. The Church had also repainted the walls and there was no evidence or

visual signs of paint flaking or staining. The relative humidity was noted at a

reduced level of 55%.

The church management committee also reported they had initiated a secondary

and further independent test and reported Calcium Carbide testing yielding

results of 2% - 4% within the church, and more importantly, these were

extracted from the fabric of the wall exhibiting complex salt deposits of

chlorides, Nitrates and sulphates which are wholly consistent with classical rising

damp.

The Calcium Carbide chemistry relied upon for site testing is essentially the

reaction between a unit quantity of material (in this case masonry and mortar)

and Calcium Carbide. The reaction liberates the gas acetylene which when

measured in a sealed unit called a “Speedy meter” provides highly accurate

moisture content of samples and subsequent results can be provided on site and

witnessed by all parties.

CaC2(s) + 2 H2O (l) ---> C2H2 (g) + Ca (OH) 2(s)

The DPA ordered further conclusive and analytical testing by extracting 16

samples from all elevations of the Church and these were confirmed by moisture

analysis yielding the range of 1.3% - 6.3% W/W. The analysis was conducted by

a technically qualified and competent analyst.

7

This wall was secondary independently tested by the Church

Flaking and Pealing Plaster before treatment

8

Table of moisture content results before and after testing

Church

Sample

Reference

Comparative

Moisture %

Pre-treatment

Comparative

Moisture %

Post-treatment

Analytical

Moisture %

Post-treatment

A 16 2 2.6

B 21 4 2.8

C 18 4 3.2

D 18 1 4.6

E 19 4 1.3

F 20 4 2.6

G 26 3 3.8

H 17 3 4.2

I 17 4 6.3

J 14 3 5.9

K 15 2 5.3

L 16 3 3.1

M 16 4 2.4

N 23 4 2.9

O 11 3 3.6

9

Rising Damp & salt Contamination

10

The Church being treated by PROsystem

11

More Rising Damp Damage

12

Moisture Content of 20% before treatment

Conclusion

The above is conclusive evidence that the PROsystem controlled the vertical

transmission of water molecules (within the fabric of the Church walls) in this

case study by reversing polarity and applying fundamental scientific principles of

Electro Osmosis, but projecting this science within an application unit has not

been achieved until now.

The importance of this system cannot be over stated, in this instance the

findings of the DPA albeit independent from the PROystem was fully endorsed by

the Church’s secondary independent testing, yielding the same analytical results.

13

The impact of these results for the industry is substantial because simplistically

put installing the PROsystem unit can control rising dampness in buildings

without the need to drill and inject potentially environmentally hazardous

materials to form a physical barrier to prevent the vertical transmission of water

molecules- which to date has been the only proven system to control this

damaging element. In addition the traditional damp proofing methods often

employ a system that requires the walls render and plaster to be removed which

can cause potential structural damage to the fabric of the building, and in many

cases involves expensive decorating costs.

The other key advantage of the PROsystem unit is when deployed in old or

historic buildings there is little or no need to remove lime or render plaster.

If these historic plaster systems were replaced with strong mixtures of sand and

cement finished with gypsum (a classical damp proofing requirement) and

therefore effectively replacing a “breathable plastering matrix” with one that

potentially traps moisture and prevents the building from naturally breathing.

Finally, the PROsystem costs are considerably less to supply and install and the

industry must consider costs along with the impact of damage to the

environment using classical systems. In this case study the classical costs would

have been of the order of £25,000 and of course the destruction of 200 year old

renders and all associated decoration costs. The PROsystem unit comes in four

sizes with a treatment radius of 11, 17, 27 and 67 meters.

The DPA has fully approved the PROsystem to control vertical transmission of

water molecules in buildings (subject to further testing).

Discussion

The PROsystem unit is unquestionably successful in controlling rising damp in

this case study, however we need to continually monitor its success in other

situations such as stone builds, concrete or cob construction properties and the

DPA is committed to confirming and publishing such results.

The DPA is currently offering a monitoring service for installations of the

PROsystem to the extent of taking wall samples for chemical analysis thus

confirming the performance of the PROsystem in preventing and controlling

rising damp in buildings and extend this to the entire UK. Readers should note

electronic moisture meters only provide a comparative reading of moisture and

must always be confirmed by chemical analysis to be exact as various

parameters can provide false readings and further lead to misdiagnosis of rising

damp by untrained personal.

Signed on behalf of The Damp proofing Association

Alan Johnson

On 17th Day of December 2014 © Copyright 2014. All Rights Reserved.

14