May 15

Earlier this year Premier Heritage carried out a full damp investigation of a semi-detached Cottage in North Wiltshire following concerns by its owner relating to damp walls in the main Sitting Room. The property which was constructed around 1898 was built with walls of 228mm solid brick and from a stone foundation.

In discussion with the client she confirmed that following her purchase of the property and within a few months, mould and damp patches started to appear along the bottom of the north and east facing walls, she also mentioned that on occasions she could actually see ‘water droplets’ in the corners.

As a result of her concern she contacted a local damp proofing company who diagnosed Rising Damp and recommended a chemical injection damp proof course (DPC). She was advised that given the plasterwork was in good condition and to save her some money and mess within the sitting room, the DPC could be installed from the exterior of the building, thus eliminating the need to hack off and replaster, although he did state that if the walls didn’t dry out with 6- 9 months, then replastering may well be necessary.

Damp wall caused by seasonal Condensation, note traces of mould to corner

Damp wall caused by seasonal Condensation, note traces of mould to corner

The occupant of some 3 years was concerned that the walls within the Sitting Room were repeatedly being affected by Rising Damp, as they were incredible wet, particularly in the corners and always evidently during the winter months!

Following our extensive investigation of not only the internal walls, but also the exterior of the building, the most astonishing feature of this survey was that this Cottage had 3 damp proof courses (DPC’s), the original slate course, a (badly installed) Ceramic Syphon Tube System (circa 1970’s) and the chemical injected system installed by the owners contractor.

Silicone Injection System, with slate course clearly visible below


Silicone Injection System, with slate course clearly visible below.

Ceramic Syphon Tube System
Ceramic Syphon Tube System

However from our own investigation and the readings taken and other data recorded at that time, there was no evidence whatsoever to suggest that the Sitting Room (or indeed nay other walls) were affected by Rising Damp, but the walls were in-fact suffering from severe seasonal condensation, and in our opinion this was always the case, given that the walls had a low Thermal Rating (solid brick) and were north facing.

Given that there was no evidence to suggest that the slate damp proof course had failed, it has to be assumed that the two further systems installed, were recommended on the basis of misdiagnosis, ignorance or mis-selling, call it what you like. Unfortunately this is an all so common problem and our client told us that she “had fully intended to call back the original damp proof contractor (who incidentally was not a PCA Member) but found he was no longer trading” as such therefore his guarantee was absolutely worthless.

Interestingly, when we asked if she had a Full Building Survey undertaken prior to her purchase, she confirmed yes, although that no damp was reported; obviously not given that the survey was undertaken in May.

Having confirmed our investigation and diagnosis in writing we were able to provide our client with practical advice and guidance on dealing with the condensation issue, which didn’t on this occasion involve another damp proofing system!!

Note: Premier Heritage undertake specialist damp investigations using a variety of detection systems and instruments, including Digital Hygrometers/ Thermometers, Thermal Imaging and Carbide Masonry Testing for a quick ‘non-destructive’ evaluation of masonry in a building. But one should not rely on these instruments alone, but should be more reliant on the users experience, eyes (visual observations) and more importantly common sense, all of which will tell you far more than moisture measuring instrument’s alone. However these instruments are there to support and aid in the diagnosis of dampness (if used correctly) and as such their importance should not be overlooked.

Apr 17

Following the horrendous weather conditions of the past months, apart from those unfortunate people who have had their homes flooded, the significant rainfall has again highlighted the problems associated with Cavity Wall Insulation and its ability to transmit moisture between the outer and inner walls of traditional cavity brick built houses. Cavities are formed for the sole purpose of keeping the weather out, if not they would be constructed with a solid wall, as they would be a lot easier to construct.

The traditional cavity wall dates back to the early 1900’s and is commonly found in the coastal areas around Britain being constructed to reduce the risk of rain penetration. In the

Cavity wall insulation

Cavity wall insulation

1920’s, local building by-laws encouraged the construction of the cavity wall and by the 1940’s it had become the Industry Standard. The typical cavity wall is two leaves of brickwork (or block), forming an approximate 60mm cavity and tied together with a network of metal wall ties.

So why do people install Cavity Wall Insulation? Well, to keep warm and save energy seems to be the normal response.

But does it really keep you warm? Is a wet wall incorporating wet insulation material a good thermal insulator?

Answer NO, a ‘wet wall = a cold wall’, so how does that keep you warm and save energy?

In the UK we are currently experiencing some of the highest energy costs ever known and our leaders i.e. our government (past and present) continue to encourage property owners to insulate their houses to SAVE ENERGY and to SAVE the PLANET.

Even as long back as the 1970’s concerns were starting to be expressed over Energy Conservation so the debate is not that new, although may now be a bit of a reality considering most of our energy companies have been sold off and most of our energy comes from Europe and beyond.

Government lead schemes such as the Green Deal and many grant aided, encourage us to insulate our lofts and cavity walls and only this week there was an feature in a local magazine which read………

”Cavity wall insulation can save you on average £190.00 per year on your bills”, ………..

Tell that to the guy whose house we recently surveyed and identified the insulation as being responsible for significant dampness and has just spent £1,600.00 plus vat, having the wet insulation removed from his gable wall due to extensive dampness affecting the porous masonry on the weather prevailing elevation of his 1970’s detached house.

The mineral wool insulation which was reported to have been installed over 25 years ago by the previous occupants was saturated at the base of the wall and in areas to in excess of 2.mtrs even effecting the wall lights, causing extensive damage to the internal decorations, plasterwork, skirting joinery and also the parquet flooring which was starting to delaminate. More worrying however, was the extent of corrosion to the electrical back boxes and brass cover plates.

Here at Premier we have investigated a significant number of cavity properties over many years, all of which had one thing in common, that various walls (particularly those of the weather prevailing elevations) were affected by significant levels of internal dampness caused by the long term bridging of moisture (rain water) through the insulation materials.

Regular readers of this site will be fully aware of the various posts on the issues of damp caused by cavity insulation materials, and this whole process can take many years to develop and obviously doesn’t affect all properties, but certainly over the past few months Premier have seen a threefold increase in telephone enquiries relating to this particular problem, given the recent weather conditions we have experienced. That said, it has to be assumed that this problem will certainly get worst in the coming years given the predicted changes in our weather patterns.

Our personal opinion is that cavity wall insulation materials (of whatever type) retrospectively installed into an existing cavity wall doesn’t really make a great deal of difference to the overall Thermal insulation value of the wall, given that most of the cases we’ve investigated over the years many were clearly not installed to the required standards, with large areas void of any insulation material and with some systems (poly beads) areas of obvious settlement.

Wet insulation materials provide no Thermal benefit!  However despite the continuing number of horror stories on the Internet, the government continue to bang the drum on the benefits of Cavity Wall Insulation, which in our opinion is NOT FIT FOR PURPOSE.

We wonder if you can get a Government grant to remove insulation, we think not!

1970s block constructed house

1970s block constructed house

Extensive dampness to wall in sitting room

Extensive dampness to wall in sitting room

Decorative damage can just be seen below the light fitting

Decorative damage can just be seen below the light fitting

Light fitting corroding and rust marks running from underside

Light fitting corroding and rust marks running from underside

Damp bridged through to fireplace stonework

Damp bridged through to fireplace stonework

Parquet floor in front of fireplace delaminating

Parquet floor in front of fireplace delaminating

Carefully cutting out the stone blocks

Carefully cutting out the stone blocks

Extent of block work removal  to remove insulation

Extent of block work removal to remove insulation

Back of blockwork clearly damp

Back of blockwork clearly damp

Insulation wet when compressed

Insulation wet when compressed

Is it supposed to stick together like this?

Is it supposed to stick together like this?

Big squeeze equals puddle of water

Big squeeze equals puddle of water


Jul 21

When one starts to trawl through articles and the Internet, it becomes very clear that to some, the whole existence of the damp proofing industry, and indeed any person suggesting rising damp occurs, is based solely on the use of an on the electrical moisture meter. The electrical moisture meter is commonly blamed for ‘misdiagnosis’ of damp problems and one individual even suggested that it should be banned!


Scores of people persistently come forward waving, for example, a piece of clinker block and show that this material when fully dry causes good responses from an electrical moisture meter and therefore, hallelujah, we lesser mortals can all be fooled into misdiagnosing the problem. Of course we all know the same effect can be gained by sticking the probes into their heads! It appears that only those that have read the manufacturer’s instructions and brought our attention to this known phenomenon have ‘the knowledge’ which will lead the unknowing out of the darkness into the light!

They also point out that electrical moisture meters do not measure moisture but electrical resistance, capacitance (impedance) and radio wave reflection. Hence, put any electrically conducting material on the electrodes and you will get a ‘result’. Mind you a carbide meter doesn’t directly measure moisture either-it measures gas pressure in a sealed space.

Those ‘in the know’ usually point out that conductance meters also respond to certain salts, especially hygroscopic soluble chlorides and nitrates, which of course is indeed a fact and is also in the manufacturer’s instructions. Now they have ‘discovered’ the presence of these particular salts in tap water, salt, animal waste, flooring materials, washed sand and so on. And as these salts are so widespread in building materials we are told they can easily ‘fool’ the unwary if one relies on identifying their presence alone as an indicator as to the source of water ingress.

However, let us take a look at the reality and the science.

The table below illustrates responses of conductance type moisture meters to air dry materials:

Response of moisture meters

When a competent, experienced surveyor is investigating a building it is known that a very few types of material such as certain clinker blocks, and some black ash mortars, will cause electrical moisture meter to respond in a significant manner; this is well documented. However, it is highly unlikely that most investigations are undertaken by directly sampling such materials with a moisture meter should they even exist in the property – in other words these situations are rare. Most electrical moisture meter readings are taken from surfaces such as plaster, render and possibly exposed brick and mortar. If one does obtain moisture meter readings throughout the whole property then any moderately competent surveyor should readily identify that there is a particular problem and this may well be due to an electrically conducting substrate. Nevertheless, most investigations are made incorporating the use of moisture meter on surfaces such as described above and not these exceptions.

So what about the composition of some commonly encountered materials in buildings?

Mains water: Legislation dictates that mains water contains up to a maximum of 50 ppm nitrate but much higher levels of chloride are allowed, probably up to around 250 ppm. Groundwater may in certain geographical locations contain higher levels. The ratio of chloride to nitrate will vary according to the water authority and groundwater in which part of the country one samples. Look up your local Water Boards’ own analyses. What becomes obvious is that you cannot specifically rely on the ratio between the chloride and nitrate in diagnosis between mains water and ground water as their origin in buildings.

As far as building materials are concerned. Water used in their manufacture (bricks, etc.) or for gauging will have used one of the sources of water, probably ground (pond/river/well) in older buildings. Thus, even the small amounts of chloride and nitrate present in such water are insignificant with regard to affecting electrical moisture meter readings, and of course they are diluted even further when mixed with mortars, limes, plasters, brick, etc. As such they will not cause an electrical moisture meter to respond significantly: in this situation their presence is of no consequence whatsoever.

Where mains water has a long history of wetting masonry directly, not via soil, then such salts may build up to a greater level where they alone can start to cause an electrical moisture meter to respond to a greater extent in the absence of free water that lead to their origin-but this takes a considerable time and is usually localised to the vicinity of the leak.

Similarly, it is frequently argued that rising damp is the result of mains water leaks in the ground. If so, (1) for water to rise the wall must be sufficiently permeable and therefore any soil water can rise, (2) mains water would pass through the soil before rising up the wall and also pick up groundwater salts in its passage, (3) any rise of water into the wall will take a long time before any significant levels of salts accumulate from whatever origin given the rate of rise of water.

Unwashed sand: almost all ‘pit sand’ is washed – it is washed in water from which it was removed! This is to remove fines (clay and silt), not salts. If unwashed ‘sea sand’ is used then distinct and significant levels of sodium chloride would be present and this would have been readily identifiable for years causing problems throughout the property in which it was used. Analysis would reveal chloride alone.

Water additives containing chlorides: the additive is usually calcium chloride (deliquescent), which form insoluble complexes with cement and as such they do not result in hygroscopic problems or detected by simple water extraction. If, however, they are mixed with gypsum plasters then hygroscopic problems do distinctly arise. But this is a use for which they are distinctly not intended.

Seawater exposure: this will occur obviously in coastal areas and any surveyor worth his salt (excuse the pun) would be aware of this. Nitrate levels in sea water are very low and contamination would effectively lead to readily identifiable levels of chloride.

De-icing salt: this would only be present to lower part of walls immediately facing adjoining treated roads. The contamination would be effectively solely chloride-sodium chloride.

Animal waste: this usually contaminates buildings where animals are kept i.e. agricultural buildings. It may only directly contaminate lower parts of walls but it can provide ‘enhanced’ groundwater salt concentrations into a wall through rising water via contaminated ground due to the waste: a lot of chloride should be expected together with ammonium salts. Nitrate does not appear to be detected in urine (human) by commonly used techniques, i.e., those used in identifying nitrates in building materials; nitrite in fresh urine indicates a medical problem.

Stored fertiliser/salted food, etc: this is rare and in most cases probably present in agricultural buildings, old meat processing areas, old bakeries, etc. It is also likely to be very localised.

Chimney flues: the result of long-term burning of fossil fuels cause the build up over a long period of time of soluble chlorides and nitrates; these are often associated with staining of a chimney breast and it will also occur on upper levels and adjacent to the chimney structure. One usually finds excess chloride to nitrate ratio in these situations, and also possibly ammonium salts. If there is a sufficient build up of the salts they will also cause visible dampness and high electrical moisture meter readings due to their hygroscopic nature.

Washing-up liquid: this was distinctly not available at the time of building houses with lime mortars: there appears to be no free chloride or nitrate present in diluted ‘Fairy liquid’ or Morrison’s, but I have no idea about Tesco, Sainsbury’s, etc. own brand. If present they would have been significantly diluted by the water and the mortars/renders into which the water was added and as such they would be of absolutely no consequence.

Electrical cables: These do not affect electrical moisture meter readings as some claim – unless you penetrate through to the wire, and you won’t need a meter to tell you that!

In relation to the presence of certain soluble salts, it should be appreciated that soluble chloride and nitrate are almost certainly present in most building materials, especially where groundwater (including rivers and ponds)/tapwater are used in their manufacture/application. But at such levels they are of no consequence and for practical purposes can be totally ignored! It is not a case of presence -v- no presence but being present at sufficient levels beyond a ‘background’ level; in other words they will have been introduced following construction from some source.

In most clean building materials, including old bricks/mortars, they are present at levels of less than 0.01% wt/wt, often far less. In almost all cases where high levels are present, sufficient enough to influence moisture meter readings, they are introduced most often in solution and over a period of time. Some seem to suggest or imply their presence at any level is akin to, “All elephants are grey; if it is grey it is an elephant”

Finally, the most important feature is that when using an electrical moisture meter or any other method of potentially looking at salt/water problems, the area should be ‘profiled’-that is how the meter readings are distributed (This also applies to any moisture and salt profiling by destructive lab methods) – it is the level and distribution of the salts that are effectively the definitive key to diagnosis. For example, if using an electrical moisture meter all readings are related to the chimney area only, it may be due to a salt problem related solely to the chimney. If the high readings are restricted to lower parts of walls only, salt and/or moisture such as found in long term rising damp may be the result – further information may be obtained by the nature of the profile. If the meter readings are obtained throughout the property, this may possibly be inherent in the building materials, etc.

Basically, any investigation is the combination of simple common sense together with using ones’ eyes, and experience – realistically a very high proportion of significant electrical  moisture meter responses will be water ingress and/or reasonable hygroscopic salt contamination, neither of which should be in the material and must therefore have originated from somewhere subsequent to construction.

Feb 28

There have been some recent events where there has been confusion and dispute over quotes/reports relating to damp and timber problems returning (or not properly rectified) after specialist contractors’ work to eliminate the problem. In many cases where the problem clearly has not been alleviated the Contractor has relied on the documentation signed at the time of the acceptance of the contract.

The following guidance should be considered by the householder (‘layperson’) should they be seeking specialists for damp and timber infestation problems.
Always ask for a survey and written report – these should describe the problems in full, give any instrument readings obtained and the methods to be used to effect a solution.
Always ask if the system being offered will cure the problem you have – always get this in writing and a full report before accepting any contract.
Always ask if there are other damp issues in your property which the system cannot rectify – get the answer in writing.
Always ask if there are any ancillary matters that are your responsibility in relation to the problems you are experiencing – if the answer is yes or even no then, again, get this clearly identified and confirmed in writing, whatever the case.
Never accept a quote only without a full report, especially if offered at the time of the visit.
Always read the report fully and any small print/guarantees and other information provided prior to accepting any work.
If you do not know the company or surveyor always ask that he is suitably qualified, – for example – one of the following qualifications CRDS, CTIS or CSRT. For waterproofing (‘tanking’) it is CSSW. These are all UK nationally recognised qualifications.
If you do not know any company then it is prudent to look for one that is a member of the Property Care Association (PCA) – member Surveyors have to be qualified as described above.
Always determine if the person visiting is simply  a SALESPERSON, say responding to your enquiry to an advertisement and just there to get a ‘quote’ or simply to sell a product/system (distinctly not advised), or is  PROPERLY TRAINED AND QUALIFIED to undertake specialist damp/timber surveys – if in doubt then ask for a specialist (qualified) from that company or select another company.
By considering the above guide, any person having specialist works undertaken will reduce the risks of dispute should one develop where the argument finally relates to the documents and contract.

Feb 23

There has been much ‘debate’ in recent years over the existence of rising damp in buildings. Indeed, there has even been a book written on the subject, “The Rising Damp Myth” in which the author claims exactly that – rising damp is a myth.

Rising damp

By definition a ‘myth’ is 1. Any fictitious story, or unscientific theory, belief, etc, and 2. Person or thing whose existence is fictional or unproven account.
As part of the introduction the author of ‘The Rising Damp Myth’ also states:
“For the fact is that rising damp is a mythical building defect, which only came to widespread prominence in the 1960s —-” and “The rising damp myth has become so powerful, and so deeply ingrained in the psyche of the construction professions, that to question it is to invite denial and even ridicule.”
So what about the truth?

Does it or does it not exist?

And do the claims made in the book ‘The Rising Damp Myth’ stand up to scrutiny or is the author simply just making it up?

To find out the truth read the independent review of “The Rising Damp Myth” and draw your own conclusions.

Download an independent Review of “The Rising Damp Myth”

Aug 18

At Premier Heritage we see many different kinds of damp proofing systems installed in properties. The document link below is to an independent review of a European system of damp proofing that we have  now seen being fitted into properties in the United Kingdom.

The document is a must read for fellow damp professionals as well as  members of the public considering the installation of a damp proofing system.

European Damp proofing system

A European damp proofing system


A Review of an Environmentally Driven Damp-Proofing System

Sep 28

A recent inspection of a 1930’s mid terraced house in Wiltshire exposed a farcical series of events due to the incompetence of the Chartered Surveyor undertaking the Home Buyers Survey and also the damp proofing specialist who (on the recommendation of the Surveyor) followed him.

This traditional cavity brick built, mid-terraced house was subjected to a Home Buyers Survey, which identified dampness within the front living room and rear dining room walls, as a consequence of which recommendations where made to instruct a Specialist Damp Proofing Co to undertake a full survey (standard recommendation) and carry out any remedial works.

After an investigation by a local damp proofing company, rising damp was identified and recommendations put forward for a chemical injection damp proof course and re-plastering to the value of £1800 + Vat.

No visual evidence of dampness to the front bay window

No visual evidence of dampness to the front bay window

Apparently happy with this quote, the prospective purchaser’s builder expressed his concerns with the diagnosis, as the property had (what appeared to be) a perfectly good slate damp proof course (as was installed at the time of construction) visible to both the front bay and rear dining room external facing walls.

A second opinion was sought and Premier Heritage were invited to undertake a survey of the property for Structural Dampness which found the following;-

  •  No obvious external defects or sources of moisture
  • No apparent internal decorative spoiling (other than badly applied wall paper)
  • No obvious plaster deterioration
  • No surface mould growth
  • No significant levels of moisture within the skirtings or adjacent timbers
  • However, high and consistent damp readings to ceiling height on both walls.

Question………What type of dampness would cause this?

Answer……….  The Metal foil backed paper type of dampness. 

Lifting the wall paper expose’s the metal foil paper responsible for the damp readings!

Lifting the wall paper expose’s the metal foil paper responsible for the damp readings!

Wrong Diagnosis

The damp problem had been incorrectly diagnosed, as it was metal foil paper (under the wallpaper) that was interfering with the damp meter, causing it to give the readings. The user should however (if he had known what he was doing) been ‘put on notice’ to the fact that the readings were consistent throughout the walls height (unusual) and that there was no obvious spoiling of decorations / plasterwork etc.

This should have at the very least, made him suspicious and he should have looked beyond the damp meter readings. More importantly is the fact that the property had a fully effective physical damp proof course.

The Outcome

The survey and investigation of dampness in an occupied house can sometimes be restricted as destructive investigation cannot always be carried out or approved. The misdiagnosis of dampness in buildings generally results from the misuse of the ‘moisture meter’ as in this case, but one should not rely on the moisture meter alone and should depend on the surveyors experience, eyes and common sense, all of which will tell him far more than the moisture meter alone. But such instruments are there to support and aid in the diagnosis of dampness (if used correctly) and as such their importance should not be overlooked.

We were somewhat surprised that the Chartered Surveyor had failed to identify the problem and far too quickly ‘passed the buck’ to the damp proofing company. We were however not too surprised with the damp-proofing surveyors findings as he was not only inexperienced, but also held no formal qualifications in damp surveying.

The foil backed paper had been applied to the walls due to the colonisation of mould during the winter months, the mould clearly a symptom of a seasonal condensation.

The foil paper, marketed as an aid to ‘damp control’, was naively applied by the Vendor in an innocent attempt to eradicate the mould, which clearly was never going to happen.

Premier Heritage identified that no structural dampness existed within this property and therefore no works were needed. Following the removal of the foil backed paper and redecoration they all lived happily ever after, apart from the surveyor and the damp-company who were asked to  contribute towards Premier Heritages costs, which could have been avoided had they looked beyond the end of their noses!

Sep 04

When the owners of a farm house suffering with damp problems needed a damp proofing solution Premier Heritage were on hand to assist with a traditional solution to damp.

This detached, stone built former Devon Farmhouse was refurbished by its previous owners in the 1970’s and unfortunately like many properties of this age was stripped of much of its original fabric, including its lime plasterwork, renders and pointing mortar.

Farmhouse prior to damp proofing taking place

Farmhouse prior to traditional form of damp proofing taking place

In early 2008 Premier Heritage received instructions from its new owners to undertake a full survey of the property for dampness and associated defects and to put forward a specification for remedial works to deal with the dampness present and any associated defects.

Drying out the dampness in the property

Drying out the dampness in the property

The main areas of concern identified by our investigation confirmed the presence of rising and penetrating dampness affecting various walls, although the latter mainly affecting the weather prevailing elevations and most noticeably the front sitting room, rear drawing room and stair area. No structural dampness was identified at first floor level.

As a consequence of the longstanding dampness to the lower sections of the south and western walls, several timber lintels were also showing signs of decay (some having already been replaced) and also death watch beetle activity.

Lintels showing signs of death watch beetle activity and fungal decay

Lintels showing signs of death watch beetle activity and fungal decay

The structural timbers supporting the half landing were also affected by wet rot where bearing into the wall as were numerous skirting and window boards.

To the western wall there was also the added complication of raised external ground levels sloping towards the house and also an obvious, insufficient overhang of the thatched roofing, increasing moisture at ground level and within the walls.

Replaced timbers

Replaced timbers

It was established that the conditions affecting this property had resulted as a consequence of the building’s past refurbishment and the removal of the original permeable mortars and renders used in the buildings original construction (i.e. the lime plaster, bedding and pointing mortar etc). Subsequent replacement with modern cement, being less permeable has resulted in dampness becoming trapped within the fabric of the wall ‘due to its inability to breathe’. This problem has built up over many years being further compounded by the numerous layers of masonry paint applied to the walls over the past 30 years or so!

Premier Heritage’s specification for remedial works concentrated on the removal of the cement materials (both inside and out) to allow the walls to dry down, along with subsequent repairs to structural and joinery timbers. The main contractor was appointed and the works were project managed by Premier Heritage.

The first task was to remove the external paintwork and cement pointing which was impermeable and trapping moisture / dampness within the wall’s, increasing the levels of dampness and internal damage to the building’s fabric. Having removed all external coatings and cement mortar (including that to the interior of the sitting room) the walls started to dry down.

New oak lintels were introduced, where existing were structurally unsound and timber repairs were completed to the interior staircase and landing etc.

Ground levels to the western wall were also reduced, with improved drainage and a vertical slate barrier fitted to the lower sections of the wall to minimise damp penetration.

Following the drying period re-pointing commenced to the exposed stone walls and this was undertaken using a lime based (permeable / breathable) mortar, after which the building was re-thatched and finally redecorated throughout.

The building has now been restored to its former condition and is dry and comfortable as well as looking great!

The finished farmhouse free of damp

The finished farmhouse free of damp

Aug 28

This 1976 brick built Dorset bungalow retained blown fibre insulation introduced in the late 1990’s.

Wall showing rain penetration

Wall showing rain penetration

Rain penetration penetrated the outer masonry and bridged the cavity causing internal decorative spoling and decay to skirting boards. Moisture entrapped within the cavity wall is clearly visible at DPC level externally and is aggravated by very hard impermeable motar.
Saturated perp end joint

Saturated perp end joint

The seriousness of this particular problem became apparent when drilling the perp end joints which were saturated.
Saturated motar between the brick work

Saturated motar between the brick work

Saturated mortar from between the brickwork.
Moisture squeezed from the insulation material

Moisture squeezed from the insulation material

Moisture squeezed from a sample of the insulation material removed.
Remedial costs to remove the insulation and make good, excluding internal repairs and redecoration, was in excess of £2000 plus VAT
Aug 28

Cavity Wall Insulation
(What are the benefits? …..…..DAMP)

From October 2008 all domestic buildings (being built, rented or sold) were required ‘by Law’ to have an Energy Performance Certificate (EPC) to help improve the energy efficiency of the building. The EPC provides an ‘A’ to ‘G’ rating for the building, ‘A’ being the most efficient and ‘G’ the least and to-date a ‘D’ rating is currently being banded as the average.

It is claimed that around a third of heat loss in a house is through its roof and walls and currently there is a government drive (supported by television advertising and the offer of Home Improvement Insulation Grants) to encourage home owners to increase loft insulation and also to fit cavity wall insulation, as it is claimed this can save on average around £180 per annum on heating costs!

However were you aware that by installing cavity wall insulation, whilst you may well be saving some money on fuel costs, you could also be creating a major expense for the future……..damp!

Example of cavity wall insulation

Example of cavity wall insulation

The cavity wall (as we know it) dates back to the early 1900’s and is commonly found in the coastal areas around Britain, used to reduce the risk of rain penetration. In the 1920’s, local building by-laws encouraged the construction of the cavity wall and by the 1940’s it had become the Industry Standard. The familiar cavity wall (as we know it) is two leaves of brickwork, forming a 60mm cavity and tied together with metal wall ties.

Even back in the good old 1970’s concerns were being expressed over Energy Conservation and home owners were then being encouraged to introduce loft insulation and it wasn’t long after that cavity wall insulation was also being recommended.

Fill your cavities with foam, polystyrene, mineral wool or any other material you can introduce through a small hole in the wall and you will save energy and loads of money. Sounds good, but what if by introducing this insulation you increased the risk of damp to your property, which in turn would cause internal decorative spoiling, plaster damage, fungal decay to  structural and joinery timbers and also accelerate the risk of corrosion to the metal wall ties.

Could that really happen? Well the answer is yes and it is.

Paul Carter, the principal of Premier Heritage, has investigated hundreds of buildings over the past 20 years of so, where damp has affected internal decorations etc and found that the damp present was due to bridging of the cavity by the earlier installed insulation materials. Whilst some of these cases were wrongly diagnosed by others as rising damp, most of these buildings (if not all) retained a physical damp proof course, the newest being a 1980’s brick built bungalow in Hampshire.

Ok, lets put this into perspective, there have been thousands of cavity built houses within the UK that have been insulated and a good majority of these don’t currently have nor will ever have a problem with damp. But there are a great number that have and no doubt more will be affected in the years to come! 

Increased rainfall in past years has resulted in a noticeable increase in damp problems affecting conventional cavity-constructed housing, due to moisture penetrating / bridging the cavities and in particular on the weather prevailing elevations and this isn’t a problem relating to current rainfall, but a gradual build of damp over many years.

Rainwater driving into the masonry of a building can penetrate the outer leaf brickwork leading to the wetting of the insulation materials, increased damp penetration and a reduced thermal performance of the material. Poor construction methods, mortar and perp joints, debris within the cavities, dirty wall ties and poor installation procedures by installers all contribute to the overall problem, which generally will result in the need to remove the insulation, which is not only expensive, but will almost certainly cosmetically scar the building when finished. Unfortunately it doesn’t come out through the same hole through which it went in!

So how do you avoid this problem? Well there’s no easy answer to this other than to look carefully at the building’s construction (porosity of building materials) and its exposure to the prevailing weather conditions. If having then decided to proceed, ensure that the chosen contractor / installer, during the survey, checks the cavities  and cavity trays for debris and dirty wall ties, but more importantly offers a system and material that guarantees (preferably insurance backed) that the materials being installed will not transmit / bridge moisture through and into the internal wall!

Alternatively, if you’re still unsure then don’t install.

Examples of Cavity Wall Insulation causing damp:

Cavity Foam Insulation

Cavity Foam Insulation

1970’s block constructed bugalow with poorly installed cavity foam insulation and debris bridging moisture via wall ties, cost around £800 to remove and rectify internal damage caused.

Polystyrene bead cavity insulation

Polystyrene bead cavity insulation

1930’s brick constructed house with polystyrene bead cavity wall insulation. Caused extensive damp to rear elevation walls, cost in excess of £3,000 to remove insulation and rectify internal damage.Polystyrene bead cavity insulation
Polystyrene bead cavity insulation

Polystyrene bead cavity insulation 2

1920’s brick constructed house, south facing elevation with polystyrene bead insulation and poor quality mortar. Caused extensive damp to internal decorations and accelerated corrosion of wall ties (rusting ends just visable), cost in excess of £3,500 to remove insulation and install new wall ties.