Archive by Author

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.

May 15

On a cold and misty morning in January earlier this year, we arrived in the town of West Bay, Dorset to undertake a secret mission on a property that was home to the fictional character DI Alec Hardy played by David Tennant in the TV series BROADCHURCH. Our mission, to carry out a full Timber Condition Survey and report any structural timber defects to our client, the prospective purchaser.

Britbank  - made famous by Broadchurch

Britbank made famous with its appearances in the recent TV series BROADCHURCH

This waterside Timber Framed Chalet located on the River Brit in West Bay was built in the early 1900,s although has been subject to much repair and alteration over the years, given its exposure to the prevailing winds and salt laden atmosphere. We were also informed that this two bedroom, centrally heated chalet, that basically stands on piles of bricks, has also come close to flooding in the past, with the water levels rising to the underside of the timber flooring.

Brick pillar

Our client at that time was planning to purchase the property and there was a requirement for a low profile, Timber Condition Survey (given the interest in the property), which we are pleased to confirm, it passed with flying colours. No significant defects or areas of decay were identified, other than general weathering issues and the need for routine maintenance and decoration.

Britbank  - made famous by Broadchurch

Front elevation of Britbank

Much of the external timber cladding has been replaced over the years, as had a good percentage of the floor platform, with the sensible use of pre-treated timbers and wall plates and the added benefit of good air flow beneath the Chalet will no doubt minimise the risk of future decay affecting the sub floor structure.

Brick pillar

Replacement floor joists supported on blocks/ bricks with slate DPC packing.

Premier Heritage’s survey involved the use of Digital Micro Drilling of original floor timbers and general investigation using moisture measuring instruments, as well as Thermal Imaging to locate the layout of the vertical timber framed walls, which did confirm that one corner of the property was in fact clad brickwork and not timber framed.

Thermal imaging by Premier Heritage

We are pleased to confirm that our client’s purchase of Britbank has now completed and allowed us to produce this short case study.

 

Dec 03

At Premier Heritage we take great delight in providing our clients with the best possible advice for looking after property. From time to time our clients take the time to put pen to paper to express their gratitude. We are proud of the feedback that comes to us from clients and would like to share the feedback with you:

Hi Paul, 

Many thanks for the report that you have completed on 3 Farthings Pitts.  

As discussed on the phone I mentioned that I was very pleased with the advice that you gave us in January 2013 regarding damp at our current house.  You gave us two options to manage the condensation problems that we were suffering – to manage the air flow or to install an air exchanger.  

We opted to try the air management system that you recommended – and for the last 2 years have kept a window open at each end of the house as well as the landing window on an almost 24/7 basis (apart from holidays or extreme cold).  In conjunction with this we have set the heating controls to ensure that the heating is more constant throughout the daily cycle rather than peaking and troughing.  

You also recommended that we were careful about the hot humid air exiting the bathroom after showers and baths, and we now squeegee the shower cubicle after use, open the windows, leave damp towels in the bathroom, and shut the door immediately on leaving the room. 

We redecorated the dining room removing the damp wallpaper, and repainted the corners of the upstairs rooms after waiting for a short period to allow the areas to dry out. 

Your advice was excellent, and has allowed us to overcome the condensation issues resulting from the house being fully double glazed.  We have been careful to maintain our routine and have had no recurrence of any condensation staining regardless of extreme damp weather conditions, or a house full of 6 adults last Christmas.  We specifically chose your service to investigate the ongoing issues knowing that you were independent, and could not have been more pleased at the quality of your report, ease to read and understand, and the value of the information given. 

We would not hesitate to recommend you to others suffering from condensation and damp, and thank you again for such good independent advice. 

We will be in touch, in due course, once all the mortgage issues are resolved in our purchase of 3 Farthings Pitts and we have moved in etc. 

Many thanks 

Dan

Daniel Hooper

B Eng  C Eng FICE

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

 

Mar 11

Premier Heritage was called upon to undertake a detailed investigation into the structural condition of the exposed timbers within a High Street, chemist’s shop, when structural movement was identified beneath one of the carrier beams and the main framing timbers on the jettied section of the building projecting over the public precinct walkway.

Exterior of property

Exterior of property

The property along with the adjoining shops had jettied sections supported on a series of timber hardwood columns, one of which supporting the main carrier beam and framing timbers being affected by long standing water penetration. This had occurred as a direct result of a defective hopper and down pipe resulting in wet rot decay to the main hardwood timbers and the top section of the supporting column, eventually leading to the compression of the column and the reported structural movement.

Damaged rain water goods

Damaged rain water goods

.

Damaged timbers

Damaged timbers

.

Compressed column

Compressed column

.

Working with and on behalf of the Insurance Assessors we were instructed to undertake a full timber condition survey to identify the type of decay, but more importantly the extent of timber replacement and this being a Listed Building necessitated the requirement to keep the replacement timbers to a bare minimum.
Our investigation involved a full visual and moisture assessment of all adjacent timbers, along with general probing using a bradawl, but also the use of the Sibert Digital Micro Probe to assess the actual condition and potential loss of fabric on the larger dimension timbers.
Some time was spent cleaning out the decayed timber and general debris from within the timber column, only to discover an active infestation by Death Watch Beetles, these clearly having infested the decaying timbers some years prior to our survey.

Damaged timbers

Damaged timbers

.

Death watch beetle damage

Death watch beetle damage

.

The outcome initiated an immediate repair of the down pipe and hopper and a proposal for replacing some secondary timbers, splicing and resin injection to the top section of the main supporting column and the introduction of some steel work to strengthen the main frame timbers. This was followed by targeted treatment of the timbers using an Insecticidal Fluid to aid with the control of the Death Watch Beetle, in conjunction with natural drying of the timber.

Our survey had obviously highlighted the need for property owners and such like, to ensure they routinely undertake inspections and report any obvious building defects before they get out of hand. In general discussion with the adjoining shop owner we were informed that the down- pipe had been leaking for some time and had been reported on several occasions, despite which no repairs had been implemented.

Nov 07
Premier Heritage have over the years undertaken investigation of some fairly horrendous attacks of fungal decay in all types of buildings which occurred as a consequence of unwanted moisture ingress and resulted in extensive damage to the interior fabric of the building, the loss of structural and joinery timbers and more importantly distress and expense to the property owners.
In a lot of cases these attacks could have been avoided with simple routine maintenance, cleaning of guttering drains etc which are one of the major contributors to fungal decay, particularly the dry rot fungus Serpula lacrymans.
When one undertakes a survey for fungal decay the initial objective is to establish the source of moisture responsible for the attack, however our recent investigation of a 1930’3 detached bungalow, initially failed to indentify the cause of a significant outbreak of decay that affected the two (back to back) bedrooms.
Our client’s first indication of anything being wrong was the discovery of a fruiting body on the external corner of a skirting, followed by deflection of the flooring this resulting in her vacating the room and her subsequent contact with ourselves.
Photo
Dry Rot fruiting body appeared on skirting board
On arriving at the property and commencing our survey the first observation made was that the attack was well away from any obvious internal sources of water (bathroom, kitchen etc) although could have been the result of a radiator pipe leak below floor level, although this may have become obvious to the occupants.
External inspection again confirmed no obvious down pipes or drainage systems adjacent to the decay and the property had a physical damp proof course and walls tested (using a moisture meter) detected no dampness to be present or to adjacent joinery, other than the skirting board above. One observation made however was that new sub floor air bricks had been fitted on to all elevations.
Why has the property got new airs we asked? We had cavity wall insulation installed about 3 years ago …………… alarm bells started to ring.
To cut a long story short having lifted the flooring within the front bedroom we discovered an extensive outbreak of fungal decay which extended through the internal wall into the rear bedroom covering around two thirds of the floor area in each room and evidently starting close to the location of the external wall and an air vent.
3 Photos
The extent of the attack exposed following removal of the floor timbers.
Upon closer inspection however we discovered that the internal vent apertures had been blocked with cavity wall insulation and also found that the internal aperture didn’t align with the air vents located on the external wall.
Photo
Insulation materials evident in air vent aperture.
. Photo
Cavity brushes used to prevent insulation blocking air vents,
although aperture clearly does not go through the wall.
During our initial survey we broke out several of the external air vents establishing that whilst the new vents installed had apparently been sleeved across the cavity (to prevent the materials blocking them) on removal they were not sleeved, but  fitted with cavity brushes, which served no practical purpose. Therefore the insulation had blocked the cavities, preventing air flow to the sub floor timbers, thus changing the environment within the sub floor void, creating damp conditions, sub floor condensation, thus resulting in the wetting of timbers and eventual development of the fungal attack.
Having established the cause and extent of the decay a specialist timber treatment contractor was appointed, undertaking the repairs and treatment of the floors, walls were re-plastered (where removed for cavity clearance) and new joinery fitted. Once the floors had been opened internally and aired and the cavities cleared etc the entire area dried down quite rapidly.
More importantly however was that every air brick fitted to the bungalow had to be individually broken out and subsequently replaced with sleeved vents directly through the walls to the sub floor area, thus reinstating the original sub floor ventilation, if not improving it!
From the point of discovering the decay to the re-occupation of the bedrooms took around 6 weeks and we are pleased (on this particular occasion) to report that the original contractors responsible for the installation of the cavity wall insulation have accepted full liability for the fungal decay as well as all costs.
How to avoid future problems? We at Premier have inspected and reported on numerous cases where Cavity Wall Insulation (CWI) materials had caused bridging of moisture through the cavities, resulting in internal dampness and spoiling of decorations etc. Whilst our own evidence suggests that installers have tightened up on their pre-installation procedures in recent years, property owners still need to be aware of the potential issues that can cause future problems and expense (particularly if the installer is no longer trading).
Energy conservation is now government lead and more and more homes are being insulated, but it is important that prior to installing CWI  pre installation checks are undertaken by the installer which should include the most important factor, its suitability for cavity wall insulation i.e. the building’s construction (porosity of building materials) and its exposure to the prevailing weather.
Other checks should include visual inspection of the actual cavity at DPC level, checking the cavity trays for debris and also for dirty wall ties, all of which are capable of transmitting moisture through a wall. More importantly check that the system (installation and materials) are covered by guarantees, preferably insurance backed.

Premier Heritage have over the years undertaken investigation of some fairly horrendous attacks of fungal decay in all types of buildings which occurred as a consequence of unwanted moisture ingress and resulted in extensive damage to the interior fabric of the building, the loss of structural and joinery timbers and more importantly distress and expense to the property owners.

In a lot of cases these attacks could have been avoided with simple routine maintenance, cleaning of guttering drains etc which are one of the major contributors to fungal decay, particularly the dry rot fungus Serpula lacrymans.

When one undertakes a survey for fungal decay the initial objective is to establish the source of moisture responsible for the attack, however our recent investigation of a 1930’s detached bungalow, initially failed to identify the cause of a significant outbreak of decay that affected the two (back to back) bedrooms.

Our client’s first indication of anything being wrong was the discovery of a fruiting body on the external corner of a skirting, followed by deflection of the flooring this resulting in her vacating the room and her subsequent contact with ourselves.

Dry rot fruiting body on skirting board

Dry rot fruiting body on skirting board

On arriving at the property and commencing our survey the first observation made was that the attack was well away from any obvious internal sources of water (bathroom, kitchen etc) although could have been the result of a radiator pipe leak below floor level, although this may have become obvious to the occupants.

External inspection again confirmed no obvious down pipes or drainage systems adjacent to the decay and the property had a physical damp proof course and walls tested (using a moisture meter) detected no dampness to be present or to adjacent joinery, other than the skirting board above. One observation made however was that new sub floor air bricks had been fitted on to all elevations.

Why has the property got new airs we asked? We had cavity wall insulation installed about 3 years ago …………… alarm bells started to ring.

To cut a long story short having lifted the flooring within the front bedroom we discovered an extensive outbreak of fungal decay which extended through the internal wall into the rear bedroom covering around two thirds of the floor area in each room and evidently starting close to the location of the external wall and an air vent.

Dry rot in subfloor void

Dry rot in subfloor void

Dry rot mycelium growth

Dry rot mycelium growth

Dry Rot attack

Dry Rot attack

The extent of the attack exposed following removal of the floor timbers.

Upon closer inspection however we discovered that the internal vent apertures had been blocked with cavity wall insulation and also found that the internal aperture didn’t align with the air vents located on the external wall.

Insulation materials in air vent

Insulation materials evident in air vent aperture

Cavity brushes used to prevent insulation blocking air vents, although aperture clearly does not go through the wall.

Cavity brushes used to prevent insulation blocking air vents, although aperture clearly does not go through the wall.

During our initial survey we broke out several of the external air vents establishing that whilst the new vents installed had apparently been sleeved across the cavity (to prevent the materials blocking them) on removal they were not sleeved, but  fitted with cavity brushes, which served no practical purpose. Therefore the insulation had blocked the cavities, preventing air flow to the sub floor timbers, thus changing the environment within the sub floor void, creating damp conditions, sub floor condensation, thus resulting in the wetting of timbers and eventual development of the fungal attack.

Having established the cause and extent of the decay a specialist timber treatment contractor was appointed, undertaking the repairs and treatment of the floors, walls were re-plastered (where removed for cavity clearance) and new joinery fitted. Once the floors had been opened internally and aired and the cavities cleared etc the entire area dried down quite rapidly.

More importantly however was that every air brick fitted to the bungalow had to be individually broken out and subsequently replaced with sleeved vents directly through the walls to the sub floor area, thus reinstating the original sub floor ventilation, if not improving it!

From the point of discovering the decay to the re-occupation of the bedrooms took around 6 weeks and we are pleased (on this particular occasion) to report that the original contractors responsible for the installation of the cavity wall insulation have accepted full liability for the fungal decay as well as all costs.

How to avoid future problems? We at Premier have inspected and reported on numerous cases where Cavity Wall Insulation materials had caused bridging of moisture through the cavities, resulting in internal dampness and spoiling of decorations etc. Whilst our own evidence suggests that installers have tightened up on their pre-installation procedures in recent years, property owners still need to be aware of the potential issues that can cause future problems and expense (particularly if the installer is no longer trading).

Energy conservation is now government lead and more and more homes are being insulated, but it is important that prior to installing Cavity Wall Insulation  pre installation checks are undertaken by the installer which should include the most important factor, its suitability for cavity wall insulation i.e. the building’s construction (porosity of building materials) and its exposure to the prevailing weather.

Other checks should include visual inspection of the actual cavity at Damp Proof Course level, checking the cavity trays for debris and also for dirty wall ties, all of which are capable of transmitting moisture through a wall. More importantly check that the system (installation and materials) are covered by guarantees, preferably insurance backed.

Sep 29

At Premier Heritage we take great delight in providing our clients with the best possible advice for looking after property. From time to time our clients take the time to put pen to paper to express their gratitude. We are proud of the feedback that comes to us from clients and would like to share the feedback with you:

Heritage Testimonial

Sep 13

At Premier Heritage we take great delight in providing our clients with the best possible advice for looking after property. From time to time our clients take the time to put pen to paper to express their gratitude. We are proud of the feedback that comes to us from clients and would like to share the feedback with you:

‘Paul was recommended to me as someone who was independent, pragmatic and well acquainted with both listed buildings and damp problems.  I had already paid £150 for a ‘survey’ from a damp proofing company that had recommended over £2,000 worth of remedial work.  Paul spent some time looking carefully at the whole property and made a number of observations that were valuable in terms of avoiding unnecessary spend, putting the damp situation in perspective and creating strategies for resolving it that were sympathetic to the property and my budget!
I would thoroughly recommend Paul – save time, effort and money and invest in an independent survey and not one by an organisation with a vested interested in creating work!’
Thanks
Mark

‘Paul was recommended to me as someone who was independent, pragmatic and well acquainted with both listed buildings and damp problems.  I had already paid £150 for a ‘survey’ from a damp proofing company that had recommended over £2,000 worth of remedial work.  Paul spent some time looking carefully at the whole property and made a number of observations that were valuable in terms of avoiding unnecessary spend, putting the damp situation in perspective and creating strategies for resolving it that were sympathetic to the property and my budget!

I would thoroughly recommend Paul – save time, effort and money and invest in an independent survey and not one by an organisation with a vested interested in creating work!’

Thanks

Mark

Jul 25

At Premier Heritage we take great delight in providing our clients with the best possible advice for looking after property. From time to time our clients take the time to put pen to paper to express their gratitude. We are proud of the feedback that comes to us from clients and would like to share the feedback with you:

Client testimonial

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!

Protimeter

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.

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