This example from a damp survey and investigation, where the repairs were carried out by Complete Preservation. You can see where I take you through my thought process of the issues, along with why I can justify the repairs needed. Traditional lime based materials will promote evaporation, and help to control rising damp issues. Unfortunately it isn’t unusual for somebody to have had a go before. If you need sympathetic rising damp solutions to include lowering high ground levels, removal of modern materials, and replacement with lime render and lime plastering, lime pointing, and modern paint removal this is the service we can carry out. We can also carry out CCTV drain surveys, drain lining, drain patching and all associated building repairs.
There will always be conflicting advice with repairing a traditional building. Fortunately the agreed joint damp methodology by RICS, Historic England, PCA, SPAB will be published very shortly, and I can only hope this sort some of this out. The new joint draft methodology – Investigation of moisture and it’s effects in traditional buildings joint damp methodology is explained here https://www.completepreservation.co.u…
Investigation of moisture and it’s effects in traditional buildings – RICS joint damp methodology. Sympathetic damp solutions to traditional buildings using lime based materials to promote evaporation. From CCTV drain survey, lime rendering, lime pointing, and modern paint removal
Damp investigations and advice will massively vary with what a client will get. This is simply because some damp investigations will not be thorough enough, and will be non invasive / non intrusive. Also it isn’t unusual to get different opinions on how to fix the issues. This is where it can get difficult especially if no data has been produced by taking plaster samples, as per BRE DIGEST 245 https://www.completepreservation.co.uk/what-is-bre-digest-245/ This then results on diagnosis confirmed just by an opinion, not by data…..If you need a damp survey that is based on opening up, data by sampling, to include drains surveys etc, please contact the office on enquiries@completepreservation.co.uk
RICS Joint Damp methodology Investigation of moisture and it’s effects in traditional buildings joint damp methodology
RICS JOINT DAMP METHODOLOGY,
Investigation of moisture and it’s effects in traditional buildings joint damp methodology, BRE DIGEST 245, BRE DG 245
Whilst this is still the draft methodology the new methodology will be published very shortly.
Do you know the questions you need to ask prior to instructing a damp specialist surveyor? This video explains and tells you the very basics that includes the facts from the British Standards
Bridged damp proof course or a bridged dpc (it’s also known as). How to repair a bridged damp proof course is only known once an invasive damp survey has been carried out. There can be many reasons why you have damp issues when a physical damp proof course has been installed, as per the diagrams in the video
Bridging of the damp proof course, or bridging of the dpc, is such a common cause of rising damp to internal walls, and also external walls. BS 6576, and BRE DIGEST 245 is the standards that all damp surveyors should be following. As per the video you need to ask your damp surveyor some vital questions. If you don’t ask these questions you might fall into the trap, and perhaps your root cause of rising damp will not be diagnosed correctly, that could result in expensive treatment and repairs. By getting the correct survey initially, it will add value long term.
1. First of all you need to make sure your damp surveyor is suitably experienced, and qualified.
2. You must ask for an invasive / intrusive survey if it’s anything to do with damp at the base of the wall, and possibly bridging of the dpc, like rising damp. Non invasive surveys will simply not be good enough.
3. An averagely competent surveyor will follow the guidance in BS 6576, as per what I have spoke about in the video.
4. They will also need to follow the methodology in BRE DIGEST 245. This is basically the only quantitative methodology to confirm rising damp, by using a carbide meter / speedy meter or better still gravimetrics.
5. Make sure all of the below are eliminated as a potential cause by your damp surveyor, as per guidance in BS 6576.
1. Condensation
2. Lateral penetration associated with ground and floor level
3. Leaks from roofs gutters, and downpipes
4. Faulty drains
5. Internal plumbing leaks
6. Water penetration through external walls
7. Water penetration around windows and doors
8. Mortar droppings in the cavity
9. History of flooding
I do find that if a physical damp proof course is present and there is damp on internal walls, there is a high possibility there could be drain issues, or a possible leak.
A rising damp survey is all about the damp investigation. The new RICS joint damp assessment methodology, which is to be published shortly goes through the stuff I go through in this, and my other videos about eliminating root cause. This video will show you how I go about some of my damp investigations, and some of the defects I find. At the end of the video I give a little bit of advice to any homeowners, on how you can potentially start your own damp investigation. Right at the end are the graphs of the gravimetric moisture profile following the guidance in BRE DIGEST 245. I explain about these in the video, and why this is important when moving forward with repairs. Any questions drop them in the comments below and i’ll do my best to answer when I get 5 mins. Have you seen the recent joint damp assessment surveying methodology by Historic England, RICS, PCA, SPAB? Click on the link below for more details https://www.completepreservation.co.uk/rics/
RICS, Historic England, PCA agreed joint damp methodology. Methodology for moisture investigations in traditional buildings. Investigation of moisture and its effects in traditional buildings.
A REVIEW OF JEFF HOWELL’S BOOK ‘THE RISING DAMP MYTH’
From ‘The Rising Damp Myth’ by Jeff Howell
“For the fact that rising damp is a mythical building defect, which only came to widespread prominence in the 1960s—-“
“The rising damp myth has become so powerful, and so deeply ingrained in the psyche of the construction professions, that you question it is to invite denial and even ridicule.”
Some recent quotes:
Architects Journal 2009:
“Rising damp is as rare as a rocking horse s**t!!”
Elaine Blackett-Ord, Blackett_Ord Conservation Architects, Cumbria: also chair of the Register of Architects Accredited in Building Conservation
Architects Journal 2009:
“Stephen Boniface, former chairman of the construction arm of the Royal Institution of Chartered Surveyors (RICS), has told the institute’s 40,000 members that ‘true rising damp’ is a myth and chemically injected damp-proof courses (DPC) are “complete waste of money”.
THE ORIGIN OF THE TERM ‘RISING DAMP’
In the book ‘The rising Damp Myth’ the author states,
“The earliest use of the phrase “rising damp” that I could find in official literature was from 1951 —“
However:-
Transactions of the Royal Institute of British Architects 1862-3
“The dry rot which had once required all the timbers to be removed, and was now again destroying them, will be prevented by the circulation of air, and the house will be as free from rising damp as if upon a gravel soil”
(from a paper on damp-proof courses and dampness in buildings)
RISING DAMP
We could define rising damp as:
The vertical movement of water up through masonry, the water originating from ground water. The water rises up through a series of interconnecting pores by a process called ‘capillarity’ – broadly, porous masonry acts like a ‘wick’.
Note: The rise of liquids from roots to leaves in plants is a process knows as ‘cohesion’ (‘transpiration pull’), not simple capillarity, and involves hydrogen bonding of water.
Rise of liquids in plants is NOT simple capillarity as indicated in the book ‘The Rising Damp Myth’!!
(Also his calculations and decimal points for heights of rise are wrong!)
RISING DAMP
Ground water contains a proportion of soluble materials, both organic and inorganic.
Of the dissolved soluble inorganic materials the most prevalent are:
Chlorides
Nitrates
Sulphates
Most building materials are, forpractical purposes, free of chloride and nitrate (<0.01% – such levels are of no consequence). However, sulphates can be present naturally at much higher levels.
So if soluble chloride and nitrate are present at readily identifiable levels they must have originated from some source.
HEIGHT OF RISE
One major factor in rise is pore diameter. Pore size in bricks/mortar can be as small as 0.001mm radius
Average size is around 0.01mm radius
A pore size of 0.01,, radius gives a theoretical height rise or around 1.5m!
Thus rising damp can rise WELL in excess of 1m, the height frequently claimed to be the maximum!
RISING DAMP
It must be fully appreciated that no walls without a physical damp-proof course will be subject to rising damp!
Therefore taking an old wall and immersing it in water will not prove or disprove the existing of rising damp as implied in ‘The rising damp myth’!
Similarly, structures built into water may not have rising damp; again, no ‘proof’ that rising damp doesn’t exist as some suggest.
LABORATORY SIMULATION IF RISING DAMP
Architect Journal 2009:
“Jeff Howell, a qualified bricklayer and author of ‘The Rising Damp Myth’ (2008) said trails in the laboratory [1993-96] confirm the falsehood [RISING DAMP]. If you build a brick pillar and stand it in a tray of water, the bricks in the water will get wet, but the water doesn’t rise by capillary action, ‘ said Howell. ‘Cement-based and most lime-based mortars will not allow water to go through.’”
BUT Letter from Jeff Howell to one sponsor in 1994:
“ In the foreground are two pillars of ibstock Red Leicester facing bricks (14% porosity) which are nicely wet up to five courses, and starting to show a pattern of efflorescence at the evaporative surface. Behind then two pillars of LBC Flettons, not so damp but, interestingly, the mortar is visibly damp up to the sixth course.”
— and Jeff Howell to sponsor in 1995:
“This wall had been standing in water for eight months, and had some hygroscopic salt contamination. It had rising damp which was visible up to a level of approximately 500 mm (six courses). It therefore represented a typical rising damp complex.”
(If it was “typical”: then, by definition, it was “characteristic/representative” of a commonly observed phenomenon, ie, it is well recorded and therefore he must have GOOD experience of it!)
On Howell’s quote:
‘Cement-based and most lime-based mortars will not allow water to go through.’
This is partly true for fresh, uncarbonated materials – but not for 80+year old materials – their permeability changes: it also depends of the strength of the mortar mix. (However, note that recently applied cement renders following dpc installation can fail in a short time, ie, let water and salts through!! Old and moderately recently lime mortars are distinctly permeable)
Cement/lime mixes in the laboratory cannot readily be aged to replicate the physical properties of the old materials – therefore the tests need to simulate the old materials!
MOISTURE METERS
IMPORTANT!
When used on a masonry substrate Electrical Moisture Meters:
Do NOT record % moisture
Do NOT record % saturation
They record a relative reading NOT directly proportional to quantity – ie, their response is non-linear
– they are purely QUALITATIVE!!
IMPORTANT!
Conductance meters do not respond to any significance on most clean, uncontaminated inorganic materials in their air dry state even under conditions of high humidity, eg, brick, mortar, concrete, paint, wallpaper paste!! There are very few exceptions!
Different materials have different ‘air dry’ moisture contents; most are not significantly hygroscopic and will absorb only very little extra moisture with increase in humidity; this does not significantly affect meter readings as claimed in the ‘Rising damp myth’
Air dry moisture contents of some materials:
Brick: 0.1 – 1.0%
Gypsum plasters 0.5 – 1.0%
Old lime plasters up to 2.0%
Cement renders up to 2.0% (appears to depend on carbonation)
Wood (organic – hygroscopic!) max of 16 – 17% in a ‘dry’ environment
PROBLEMS WITH ELECTRICAL
MOISTURE METERS
They are too sensitive and it takes skill to interpret results
Erroneous results can be obtained by:
Contaminated salts, ie, hygroscopic salts only!
Some materials containing carbon or other electrically conducting material (rare and local knowledge)
Foil backed paper (experience)
Surveyor’s fingers on the probes!!!
BUT over 99% of high figures will be the result of water and/or hygroscopic salts, neither of which should be in the masonry and must have therefore arisen from somewhere!
In the book ‘The Rising Damp Myth’ it is reported that one RICS Surveyor’s notes state, inter alia, the following:
“Older properties tend to have an accumulation of surfaces salts due to years of evaporation. These salts, whether hygroscopic or not, will lead to readings on a protimeter a zone or two higher than the actual amount of water present.”
BUT
Only hygroscopic salts will cause high readings. Efflorescent salts alone in an air dry substrate DO NOT!!!
Where did the water come from to result in “years of evaporation”??
Only a very few building material will cause an electrical conductivity meter to respond significantly in the absence of free water and/or hygroscopic salts!
Over 30 years of sampling experience has shown that this reported ‘natural’ surface salt problems is not the case.
DIAGNOSING RISING DAMP
TOTAL MOISTURE CONTENT
of brick/mortar/plaster, etc, is potentially
the sum of 2 components:
AIR DRY (HYGROSCOPIC MOISTURE CONTENT
Moisture in a material when it is in equilibrium with the air. It is what we
would regard as a ‘dry’ material, ie, when there is no water ingress. It is a
material’s ‘standing’ level of moisture.
CAPILLARY (OR FREE) MOISTURE CONTENT
Moisture that fills the capillaries of the material. It is only present what there
is an active source of water ingress, eg, rising damp, water penetration, etc.
It is this water that usually causes problems.
Principal:
If the sample loses weight it has dried out
ie, it contained capillary (free) moisture and therefore it was subject to a source of water ingress at the time of its removal
If the sample does not change in weight (or gains) it was ‘dry’ (not subject to water ingress) at the time of its removal.
Note: the method basically identifies the presence of water ingress, or not –
it does not necessarily, on its own, identify specifically rising damp-and certainly not from a single sample!
The author explains the Building Research establishment Digest 245* method in ‘The Rising Damp Myth’but he has completely misunderstood how the results are interpreted!
He states that if the sample gains weight then:
“— it was contaminated with salts (and therefore possibly affected by ground water)”
(Note: could “ground water” and salts be from the ‘mythical rising damp’??)
If it loses weight the:
“–it’s moisture content was more likely due to a non-salt contaminated moisture source, such as rainwater or condensation”
The above interpretations are WRONG! For example, if the sample loses weight it simply shows that it was subject to water ingress FROM SOME SOURCE, eg, water penetration, rising damp. If it gains then it was ‘dry’ (no water ingress) and removed from a relative humidity lower than that of the test – it does no necessarily reflect salt contamination!
This could explain why the Author has never found rising damp (and never would on his interpretation), and begs the question, has he ever used the method??
*BRE Digest 245: ‘Rising Damp in Walls: Diagnosis and Treatment’
THE GROUNDWATER SALTS
(HYGROSCOPIC SALTS)
Hygroscopic salts absorb water from the air
They are rarely seen on surfaces BUT their effects are on the form of visible dampness/high surface moisture meter readings.
Their most common origin is rising damp, and sometimes around old chimney flues where they arise from the long tern combustion of fossil fuels
Hygroscopic salts are frequently referred to by those who state rising damp is a myth, and blame these salts, in part, for misdiagnosis or rising damp using moisture meters.
– but given that almost all building materials are effectively free from such salts, those that support the ‘myth’ never seem to explain how they only contaminate and are distributed in the lower parts of the walls!
MANIPULATING THE MYTH
Jeff Howell in ‘The Rising Damp Myth’ quotes the following:
“Bob Sharpe (1978) found that pressure injected of the damp-proofing fluid into his test pillars “ – was completely ineffective in producing a damp proof course-it was clear that no damp proof course had been established in either brick or mortar at any stage”
Sharp found that “-this had not been enough to produce an effective damp proof course”.
However, under both ‘Abstract ‘ and ‘Conclusions’ in the same paper Sharpe concluded:
“ 4. A test wall was constructed using a particular grading of washed sand in which a substantial moisture gradient was created. When this wall was injected an effective damp-proof course was formed. This could well form the basis of a realistic performance test of damp proofing treatments,”
So why the difference from the same paper?
The author of ‘The Rising Damp Myth” chose to quote from the mid-part of the paper where the test was being developed – not the final evaluation and “Conclusions”!! This is distinctly false and grossly misleading!!!
LUDICROUS OR JUST A ‘GOOD STORY’?
From ‘The Rising Damp Myth’:
“I had told him [Sharpe] that I had been unable to find a single case of genuine rising damp. His reply was short and to the point. “Well”, he said, “Neither could we”
Howell continues:
“And Bob Sharpe was the BRE’s top expert on dampness in buildings. He was the author of many papers, reports, and digests on the subject, including the landmark BRE Digest 245*, which presented the definitive official view of the diagnosis of rising damp. To hear him say that he never found a genuine case of rising damp in the British house was astonishing.-it was still odd to hear from the top expert that the whole subject of “rising damp” and – by definition – the entire workings of the British damp-proofing industry, were based on the myth.”
Note: If Howell had never found a case of rising damp then how did he describe earlier it as “typical” during his experiments in 1995?
*BRE Digest 245: ‘Rising Damp in Walls: Diagnosis and Treatment’
But:
If, as alleged in ‘The Rising Damp Myth’, that Sharpe and hence Building
Research Establishment
“had never found a genuine case of rising damp in the British house”
then one must ask:
How did Sharpe and BRE manage to develop tests and publish “-many papers, reports and digests on the subject” for years including Digest 245 (and earlier TIL 29) for diagnosing rising damp, about something they had never found out? (also note the author of ‘The Rising Damp Myth’ describes the Digest as “landmark” and the “definitive official view of the diagnosis of rising damp”!!)
Who forged and labelled the photos and data in the Digest? And who fabricated the whole story in the Digest and other BRE papers and publications over such a long period (OVER 40 YEARS) – and still going?
And, of course, what Government Departments authorised the funding for the BRE research, publications and their circulation over many years knowing that resulting publications by BRE where fabricated?
And from the RICS:
Jeff Howell tells us that, “__ Bob Sharpe — was the author of many papers, reports and digests on the subject, including the landmark BRE Digest 245*, which presented the definitive official view of the diagnosis of rising damp.”
* The diagnosis described in the Digest is based on destructive testing and lab facilities to produce vertical moisture profiles of 6-8 samples per profile, to determine the distribution of water (hygroscopic and free in each sample). In essence this is the only definitive method of diagnosing rising damp.
So in a statement from Stephen Boniface, Chair of the RICS Building Surveying Faculty, recorded in the book, Boniface reports, inter alia, “-I and others within the RICS have been lecturing for years now that rising damp is misdiagnosed in over 90/95% of cases —“ [so he says 5/10% are correctly diagnosed – but he’s previously stated rising damp is a myth!]
Given that to positively identify rising damp it requires a combinations of destructive sampling and laboratory facilities, one must ask on what objective evidence does Boniface and the others base this statement given that it is highly unlikely that they have sampled and analysed anything like sufficient properties (if at all) to objectively evaluate different forms of dampness to draw that conclusion.
Boniface’s figure is pure conjecture with no substantive validation provided!
Yet another good ‘story’?
In ‘The Rising Damp Myth’ the Author states that at Audley End in Essex, “Drilled samples shows that the wall was wet, and with the pattern of moisture distribution – wetter at the bottom and with a band of salt staining half way up it seamed to bear all the hallmarks of being affected by rising damp”
He continues, “The Building Research Establishment thought they had found rising damp in the boundary wall, but once it was covered with a tarpaulin to keep the rain off, it dried. “and” – The “rising damp” had been nothing of the sort, and the wall had simply been getting wet from the rain.”
[Note: Howell states that BRE “— thought they had found rising damp –“!!
But previously he extols BRE for producing the, “ landmark BRE Digest 245, which presented the definitive official view of the diagnosis of rising damp.”
Fact:
BRE had fully identified rising damp in this wall by analyses. They found the distinct ‘salt band’. (If it was just rain penetrating then from where did the salts and the ‘salt band’ originate in the lower part of the wall?)
During the long drought of 1984 the ground water dried out as did the wall – rising damp did not recur even through BRE wetted the ground.
Note: again, the version of events described by the Author suggest that BRE were not competent at identifying rising damp even after all their years at work in producing Digest/papers on the subject, and notwithstanding he states that, “- Bob Sharp was the BRE’s top expert on dampness in buildings.!
Finally, a full technical review of Rising Damp has recently been published
‘A review of Rising Damp in Buildings’
Dr Zongyi Zhang
Advanced Polymer and Composites (APC) Research Group
University of Portsmouth
A review contains over 50 worldwide references to
Rising Damp in Buildings
British Standard 6576:2005:
‘Code of practice for diagnosis of rising damp in walls of buildings and installation of chemical damp-proof courses’
The Author of ‘The Rising Damp Myth’ quotes the following:
“Bob Sharpe told me that there were two main reasons why the BRE was under pressure to produce rising damp in the laboratory.
The other reason was to contribute to the writing of British Standard 6576. The British Standard committee for this purpose included representatives from the major damp-proofing companies, who had themselves been unable to reproduce rising damp under laboratory conditions.” (my note: yes they did!!)
BS Committee responsible for BS 6567:
Association of Building Engineers
Autoclaved Aerated Concrete products
Brick development Association
British Board of Agreement
British Masonry Society
British Precast Concrete Federation
British Wood Preserving and Dampproofing Association
Building Research Establishment
Concrete Block Association
Eurisol – UK Mineral Wool Association
Institution of Structural Engineers
Mortar Industry Association
National House-Building Council
Office of the Deputy Prime Minister (Building division)
Royal Institute of British Architects
Stone Federation Great Britain
It is unreasonable to have one representative out of 16 from such an industry for a British Standard on rising Damp and damp-proofing!
It also begs the question why would a group of such eminent and knowledgeable organisations, including BRE, RIBA, experienced in the built environment, gather and conspire and fabricate a British Standard (in 1985 and 2005) about a matter that is, according to Howell, a complete ‘myth’ and doesn’t exist??
Review and conclusion:
Based on practical and supplied evidence from a large number of sources,
Including peer-reviewed institutions:
Rising damp is a well understood and identified feature which can occur in some buildings – it is a FACT, not a myth, and NOT originated or perpetuated by the UK damp-proofing industry
Rising damp has some unique features which can be readily diagnosed using basic and authoritative analytical methodology
Rising damp does NOT affect all houses without physical damp-proof courses
‘Rising damp’ has been observed and reported from at least the early 1800’s, ie for nearly 200 years
Rising damp is well recorded in Australia, Belgium, Denmark, Hungry, France, Italy, Spain, indeed, across Europe, South Africa and the USA, all of which have produced authoritative peer-reviewed publications on this subject. It is not solely a UK problem!
Electrical moisture meters are extremely useful as an aid in diagnosing dampness and associated problems (hygroscopic salts) provided they are used intelligently and their limitations and performance well understood.
And the ‘Rising Damp Myth’ by Jeff Howell?
Very poorly researched – oblivious (or massive selective amnesia?) of authoritative worldwide peer review publications/investigations undertake by qualified scientist/engineers, and evidence of rising damp and its history.
Very poor science (where it even appears) and failure to understand it; no objective rigor to his ‘investigations’.
Non-supportable anecdotal evidence and grossly misleading ‘facts’ – some are nothing short of ludicrous and illogical.
Highly likely fictitious conversations/situations not consistent with publications/known history.
Lack of validation of so-called ‘facts’. Misquoting to support a ‘story’
Overall, the publication appears to reflect the author’s poorly research work in an attempt to disprove, for some reasons unknown, a well review, obvious, and a proven and readily diagnosed phenomenon recorded for at least nearly 200 years. His attempt to support his self proclaimed ‘myth’ by some ludicrous, illogical and decidedly misleading ‘facts’ is simply incomprehensible.
I was recently asked to carry out a damp investigation to a property where damp issues had persisted for many years. My client had received conflicting advice from a number of different damp and lime experts. Some of this advice was to remove any modern materials and replace with lime render and lime plaster. Remove modern paint, and repoint with lime pointing putty. Other advice was to use a modern guaranteed system and damp proof walls. Another free damp survey specified to increase the ventilation in the property by installing a positive input ventilation (piv).
In this instance this is where it can get very worrying, as potentially a serious amount of money is about to spent, and neither of this is actually going to fix the root cause. This is a common scenario when a homeowner is a layperson and has no knowledge of how a damp survey should be carried out. Lets face it most people that come around to a property have a service to offer, and im sure most people are just trying to earn a living without the intention of trying to rip anybody off.
This job could have gone horribly wrong if our client hadn’t been advised by a family friend just about before she was going to have the lime plastering and lime pointing carried out to her Wiltshire property. Her friend advised her to contact me as we’ve recently helped out another friend with a very similar conflicting rising damp issue.
The damp survey
The art of any damp investigation is all about elimination of the root cause before coming to a conclusion. The well documented BRE digest 245 methodology is what I would say an averagely competent damp surveyor should follow, and this should aid any survey findings. The reason I say this is because this methodology is recommended guidance in every British Standard in regards to damp. In this instance at this property the mortar sampling was very wet at the base of the wall (20% capillary moisture), along with a very low hygroscopic value (1.1%), with no high levels of nitrates or chlorides. By following this methodolgy and removing the plaster samples for analysis, I was able to confirm something that none of the previous surveyors, contractors, lime specialists had even mentioned.
All of this points to either a mains leaks, plumbing leak, or drainage leak. This high amount of capillary moisture, along with a very low amount of hygroscopic value, is indicative of rising damp caused by excess water from a defect. True genuine long term rising damp always has hygroscopic salts like chlorides, and / or nitrates present.
I used our signal generator Ridgid SR20 to actually locate and trace the mains water coming from the road and into the property. Because the property had been extended, the original main was hidden under new concrete solid floors to the side extension. Once this was located I was then able to use My Aquaphon acoustic leak detection equipment all the way along the pipe to listen for any possible mains water leaks.
The property had some older original drainage systems in place, and some fairly modern drainage. I used my Ridgid drain CCTV inspection camera to inspect all drains around the property.
What I found during the CCTV inspection was that the drains were in need of urgent repair, as these defects were directly related to the amount of moisture that was producing rising damp symptoms within the property. What was good, was that my client was there and could view the camera inspecting the drainage for all the issues that I noted.
I used a tracking dye and a bung to flood the drains to exaggerate the issue, to track the path of the water. What I also found was that this drainage issue also caused damp issues to the cavity construction part of the extension also, as I was able to see it within the cavity wall.
By using Complete Preservation for the initial survey, we were then trusted to specify the repairs to the building to resolve the rising damp issues.
As always budgets can be limited so quotations are really based on what needs to be done ASAP, and at what cost.
I specified drain patching, which was needed in numerous locations, along with connecting an old soak away to mains drainage, as this wasn’t draining as desired.
Ground levels were lowered as per our typical drawing.
Modern masonry paint is to be removed at low level (150mm from the floor) to aid evaporation at the base of the wall. Lime putty repointing was also specified for low level areas where pointing was needed.
Please see the below video of a 1 minute demo of how to remove modern masonry paint, and how to lower the high ground levels.
Top tip
Before you spend money on any damp proofing works, or even lime plastering, lime rendering, lime pointing in regards to damp issues, it would be worth paying for professional guidance to eliminate damp root causes. It would be prudent to have a CCTV drain survey, leak detection, and also mortar/plaster sampling following the methodology in BRE DIGEST 245 where needed. The reason I say this is because I’ve seen numerous lime plastering jobs fail because none of the above has been carried out. Lime plastering is a fantastic product, but it isn’t going to perform as desired when there are defective drains, and the walls are very wet. When walls are very wet it is also a good idea to use some drying equipment to lower the moisture content of the wall.
If you need further advice regarding damp issues and lime plastering costs please email enquiries@completepreservation.co.uk
First of all lets just agree that rising damp occurs. It might get mis-diagnosed by damp surveyors, and it also might not get resolved first time.
It isn’t unusual for people to have spent a few thousand on surveys and damp repairs and still have damp issues. Elimination of all potential causes before coming to a conclusion is essential to ensure the correct diagnosis, and move forward with options of repairs.
High external ground levels are a common issue when it comes to rising damp. High ground levels contribute to the height of which rising damp can rise, as it will restrict evaporation at the base of the wall.
General external basic defects like guttering leaks, and drip detailing also need to be rectified. It is always advisable for you to monitor your building during heavy rain to see how your building is dealing with rainwater. It is easy to spot guttering defects, and possibly a blocked drain.
French drains, or French moats as many people call them actually cause more of an issue in regards to damp. This is because they never get maintained, they can’t get inspected unless a CCTV drain camera is used. If a drain blocks, and surcharges these often get filled with silt etc, and even tissues if connected to a foul drain.
The pictures below from a recent damp survey highlight the above issues with flooded French drains, silt build up, along with root infiltration.
Drains are perhaps one of the biggest contributors to rising damp issues. These rarely get inspected as generally most surveyors don’t own any drain surveying equipment.
The picture below shows a CCTV drain survey picked up the cause of this long term rising damp issue in Wiltshire. As you can see there is a damage to the drain pipe that is connected to the toilet. This cause of rising damp and a rotten suspended timber floor couldn’t of been found without a CCTV drain survey.
We understand how to find and diagnose all types of damp issues, and also have the experience, and know how on how to repair any defects.
If you need a damp survey to help locate potential causes to offer a long term solution, please give us a shout.
Complete Preservation carry out CCTV drain surveys, along with drain repairs using our unique drain lining / patching system with fast cure times. Our drain patching system is a no dig system, which means most repairs can be carried out below ground, without any disturbance to above ground areas. This can save time and money if drives, paths, and even home internal floor finishes can remain in situ. The below image demonstrates a damaged drain pipe on the left hand side, and a drain lining system that has been installed on the right hand side.
Damaged drain symptoms
If you have rising damp issues on your external or internal walls, damp or flooding in your sub floor void that’s causing dry rot or wet rot, blocked drains, slow draining drains, walls that have cracking / subsidence, this is likely to be related to drain defects. These defects could be caused by root intrusion, and damaged/cracked drains, and need to be inspected and possibly be eliminated with a drain CCTV camera to prevent further issues.
We offer quantitative moisture analysis when it comes to rising damp, following the methodology in BRE Digest 245, along with all types of sympathetic damp repairs, dry rot and wet rot repair, to include drying of sub floor voids.
Contact us to discuss your issues, and we can offer you some professional guidance where needed.
It is part of Building Research Establishment (BRE) digests on authoritative summaries of state of the art on specific topics in construction design and technology. They draw on BRE’s expertise in these areas and provide essential support for all involved in design, specification, construction and maintenance. This particular document can be purchased direct from BRE for just £15.00 here https://www.brebookshop.com/details.jsp?id=287528
This Digest considers the causes of dampness in walls and offers a positive method for diagnosis of rising damp. It suggests possible remedial measures that can be taken to avoid rising damp such as providing a complete moisture barrier by insertion of a physical damp-proof course or the non-traditional method of chemical injection. The repair of plaster damaged by damp is also discussed.
Mechanism of rising damp
For water to rise in a wall, a supply must be available at the base. If the ground surrounding the wall is saturated, this condition is achieved, but if the ground is not saturated the soil will exert a suction that will oppose the upward capillary pull on the water in the wall. This suction is approximately equivalent to the negative pressure exerted by a column of water extending from the base of the wall to the water table. If the water table falls, the height of the moisture in the wall will drop to a new level provided there is sufficient time for equilibrium to become established. Each period of heavy rain on the ground at the base of the wall will produce a temporary condition of saturation and the water level in the wall will begin to rise again.
The level to which it rises depends on two factors: the amount of evaporation of water from a wet wall and on the resistance to the flow of moisture up the wall. If this resistance is high (as in a material with many fine pores), the effect of evaporation is most marked reducing the appearance of rising damp, but if the wall material has many coarse pores, the height of dampness will be only slightly affected by normal rates of evaporation.
Increasing the heat input to the structure will increase the rate of evaporation from the wall surfaces. The overall effect is to increase the rate of flow of water up the wall but because of the resistance to flow this is likely to be accompanied by a reduction in the height to which the moisture extends.
In addition, evaporation will occur from deep in the pores of the plaster so that the rising damp seems to disappear. In summer, hot weather will increase the evaporation rate and lower the water table so the effect of reducing the appearance of the rising damp can be even more striking.
Water drawn from the soil usually contains a low concentration of soluble salts and the rising water will also dissolve salts present in the bricks or the mortar. When evaporation occurs the salt solution becomes more concentrated at the surface and eventually the salts will crystallise out. This tends to block the pores, reducing evaporation and hence raises the level of dampness. These salts may also be hygroscopic and will absorb moisture from the air above some critical value of relative humidity so that the surface becomes wet during wet weather, although this dampness disappears when the air becomes drier again.
All this suggests that under real, dynamic conditions rising damp in a wall is often in a rather sensitive equilibrium which may be considerably disturbed by changes in the heating of the building and in the level of the water table. The presence of hygroscopic salts tends to obscure any drying associated with such changes by keeping the wall more moist than it would otherwise be. If such salts are removed from the surface by removing the old plaster, and the heating system is improved, it is likely that the apparent dramatic improvement in the appearance of the wall surface will give the impression that the rising damp has been cured when this is not actually the case. It is against this background that the correct diagnosis of rising damp becomes important.
BRE DIGEST 245 is the only way to offer quantitative moisture analysis to prove if a wall has rising damp. This is well documented in the British Standard, BS 6576, BS 5250. BRE digest 245 clearly shows multiple pictures of possible causes of rising damp where there is a physical damp proof course installed that has been bridged by one way or another.
The above image shows rising damp being caused by the damp proof course being bridged by the plaster
The above image shows rising damp being caused by the damp proof course being bridged by mortar in the cavity.
The above image shows rising damp being caused by the damp proof course being bridged by the path or just high ground levels
The above image shows rising damp being caused by the damp proof course being bridged by pointing over the damp proof course
The above image shows rising damp being caused by the damp proof course being bridged by the external render
The above image shows rising damp being caused by the damp proof course being bridged by the floor screed
Obviously solid wall properties built before a physical damp proof courses were installed can still have similar causes like high ground levels, modern renders rendered to the floor etc, that can cause rising damp issues. Many older properties also had land drainage incorporated around the property which were installed if an area was deemed to be very wet, which is discussed BRE DIGEST 245. I’ve personally noted this on many of the older historic local buildings I have worked on in the area. This is an extract from my local Bye-laws of the in Warminster Local Board from 1858. Drainage of subsoil and prevention of damp. The house drainage shall be constructed, either with additional eathernware pipe drains or otherwise, as to drain the subsoil of the premises, whenever the dampness of the site appears to the Board to render this necessary; and all the rain-water shall be so drained or conveyed from the roofs of the buildings as to prevent its dripping on to the ground and causing dampness in the walls.
In addition, evaporation will occur from deep in the pores of the plaster so that the rising damp seems to disappear. In summer, hot weather will increase the evaporation rate and lower the water table so the effect of reducing the appearance of the rising damp can be even more striking.
Water drawn from the soil usually contains a low concentration of soluble salts and the rising water will also dissolve salts present in the bricks or the mortar. When evaporation occurs the salt solution becomes more concentrated at the surface and eventually the salts will crystallise out. This tends to block the pores, reducing evaporation and hence raises the level of dampness. These salts may also be hygroscopic and will absorb moisture from the air above some critical value of relative humidity so that the surface becomes wet during wet weather, although this dampness disappears when the air becomes drier again.
All this suggests that under real, dynamic conditions rising damp in a wall is often in a rather sensitive equilibrium which may be considerably disturbed by changes in the heating of the building and in the level of the water table. The presence of hygroscopic salts tends to obscure any drying associated with such changes by keeping the wall more moist than it would otherwise be. If such salts are removed from the surface by removing the old plaster, and the heating system is improved, it is likely that the apparent dramatic improvement in the appearance of the wall surface will give the impression that the rising damp has been cured when this is not actually the case. It is against this background that the correct diagnosis of rising damp becomes important
Experience has shown that it is much more difficult to diagnose the source of dampness in a wall than is generally supposed. It is particularly difficult where the presence of some soluble salts greatly complicates the situation, especially when just a damp meter is being used.
BRE DIGEST 245 is guidance on the diagnosis of rising damp on a rational basis. The basis of the method proposed is to to drill samples, from the wall and measure the free water value and hygroscopic value of the said samples. The aim is to establish whether any dampness damage is caused by rising damp as opposed to other processes, then a location away from other sources like drains, gutter leaks etc. If visible damp or high damp meter readings are located on external and internal walls, ideally many samples should be taken as multiple causes could be causing the symptoms.
Once all of the laboratory analysis is finalised, then we can produce a graph detailing the moisture, and this will help determine the damp issue.
Whilst gravimetric sampling is far superior than using a carbide meter/speedy meter, it is imperative that the guidance in BS: 6576 is used to eliminate other potential causes. An example being that perhaps gravimetrics have proved that rising damp is a cause of the decorative internal spoiling, which is the actual sympton of rising damp. The actual cause of the rising damp could still be something like damaged below ground drainage that would need to subjected to a CCTV drain survey. Gravimetrics and hygroscopic salt analysis sometimes points to there being no nitrates or chlorides present, which then points to drain issues or leaks within the property. This means that finding the root cause, and drying of the building is all that is needed, rather than removing all of the plaster and getting it replaced.
Whilst it sometimes might sound like a slow process and unduly complicated, but no simpler procedure has proved to be reliable.
Some damp issues can cost a small fortune to fix, and so can the amount of errors in damp diagnosis by damp experts. This is why it is imperative that the diagnosis is correct first time.
If you need advice regarding damp issues, give us a shout.
I was recently contacted by a landlord to dry down a property after a leak on a new build property. There have been 2 previous plumbers that had been instructed to find the leak and rectify it. I was of the understanding they had carried out what they had been paid to do. When I visited the property to install our Corroventa drying equipment, it was obvious to me there must still be a leak as I could see water droplets on the ceiling. The ceiling seemed in pretty good condition with the possibility of being saved. I wanted to do the least amount of damage possible to keep the cost of the repairs down. By using my Sewerin leak detection equipment I found the leak, as I could hear the dripping noise ever so slightly. This isn’t something you could hear without the acoustic listening equipment. And by using a Ridgid snake camera I could actually see the leak, and dripping of the water in the ceiling void.
The leak was on the cold feed to the sink on the push fit connection.
The leak was fixed and drying equipment installed. The Corroventa drying equipment is controlled by SuperVision, which also offers real time data logging. This equipment is worth it’s weight in gold during the hot weather as I could turn off the system if it became too hot in the property, or the tennant wanted it switched off at night. I also set high threshold alarms to alert me of high temperatures within the property.
If you have a leak or a damp issues give us a shout.
This is a property I have previously surveyed last year, where there were issues with penetrating damp. We found external issues with rainwater goods, peeling modern paint, rotten timber lintels etc. We removed the modern masonry paint using our Thermatech super heated hot water system, repointed in lime, lime rendered the rear wall, and the client carried out the lime wash finish. We also removed and repealed the lintels. This year it was about getting the rising damp source identified, and some form of sympathetic damp repair. This video is a classic example of you get what you pay for, in regards to damp surveys. We don’t offer free damp surveys because we offer professional surveys, and reports. If you need to find the source of rising damp, penetrating damp, or condensation give us a shout. We offer quantitative damp diagnosis following the methodology in BRE DIGEST 245.
