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

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 mycelium growth

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 evident in air vent aperture

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.

]]> http://www.premier-heritage.co.uk/2011/09/another-delighted-client/feed/ 0 http://www.premier-heritage.co.uk/2011/09/839/ http://www.premier-heritage.co.uk/2011/09/839/#comments Tue, 13 Sep 2011 15:17:07 +0000 Premier Heritage http://www.premier-heritage.co.uk/?p=839 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

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:

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.

We were called in to advise the owner on the type and causes of wood rot affecting the plywood timber decking forming the accommodation area of the motor home, this recently discovered during his routine ‘spring clean’ of the vehicle in preparation for use over the summer.

Motorhome with a wood rot problem

The obvious cause of the wet rot decay was due to the timbers contact with moisture, in part due to the poor detailing and water proofing of the structure beneath the vehicle and the sawn ends of the decking which are exposed within the side storage boxes.

Wet Rot affected timbers

Wet Rot in a side storage box

We are pleased to confirm that with a bit of help from Premier Heritage the owner has now reached a satisfactory agreement with the suppliers / manufacturers of the vehicle and repairs / modifications are currently in hand.

What to do if you suspect Wet Rot in a motorhome / caravan

It is important to get any signs of wood rot checked out by a professional qualified surveyor  who will be able to diagnose the type of wood rot (Wet Rot, Dry Rot etc) and help advise the best cause of action to take.

 
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.
or,
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.
 
FINALLY and VERY IMPORTANT:-
 
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.

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”

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.

A European damp proofing system

A Review of an Environmentally Driven Damp-Proofing System

The photographs we have on display show a variety of insect infestations along with the culprits responsible for the damage, as well as wood rotting fungi and numerous types of dampness.

Environmental conditions within a building, structural dampness and building defects all contribute to the causes of fungal decay and in some cases accelerated beetle infestation and to minimise the risk of timber decay and other problems good property maintenance is essential.

The photographs shown are for interest only and should you require guidance or advice on any particular concerns affecting your own property then please do not hesitate to contact our office to discuss or arrange an independent survey of your property.

See also our building defects the maintenance section, showing photographs of a range of common building defects that are responsible for and or contribute to structural dampness and timber defects in properties.

To visit the photo library click on the Photos section on our navigation!