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Rising Damp? Myth?



  • danderdander Forumite
    1.7K Posts
    Part of the Furniture 1,000 Posts Combo Breaker
    Well the fact that the report says "seek further specialist advice" means the surveyor is covering his back. He's found and reported moisture, that's all.

    What age is the house? Are the solid floors original or have original suspended floors been replaced with solid? If the house is exactly as built it would be pretty strange for an entire damp proof course to fail across the entire building, it would seem more likely that damp that widespread would be due to internal atmospheric conditions.
  • garthdp wrote: »
    I had the same thing when I bought a 300 yr old cottage ten years ago
    I was told that remedial damp work up to the value of £7000 was required!!!A retention of that sum was placed on the mortgage in lieu of getting the work done which, as I did not have that kind of money to spare meant the sale was effectively off.I argued the toss with the mortgage co who eventually reluctantly gave in and lent us the money anyway.

    The cottage which had no DPC ( well they didnt use em in 1789) and was a holiday home and rarely used when we bought it was absoloutly fine once we started living in it and airing it etc.

    The cynic in me says these reports are just ways of one 'profession' providing another with access to your cash for no reason.

    That happened to us we were told there was rising damp and it did smell mouldy but once we started living in it it improved and within six months of daily airing things were better with no later problems.
  • Dry_RotDry_Rot Forumite
    51 Posts
    So they are totally useless on 3' to 4' thick solid stone walls built straight on the ground then?

    Thought so!

    The reason a dpc will not stop rising damp if the cavity is blocked is because the debris in the cavity bridges the system. Solid walls are easy to treat. cavities are easy to unblock too.

    I installed my first chemical DPC in 1976. Since then I have, through my company installed several thousand. Most work fine - some have failed and we've had to sort them out. The failures have always been due to either:

    My stupid specification (it is specialist work and it took me years to get the expertise I now have).

    My technicians being lazy and cutting corners (some peole do this when the boss isn't looking). The problem is all but elliminated now with the advent of injection creams, which are so easy and fast to use.

    CSRT is the national qualification which at least lets clients know that the surveyor has taken the time and the trouble to learn about the problem and has ben examined by someone independent. It is not very hard, so if a 'specialist' has not got it, he is either dumb, or can't be bothered. In which case stay clear.

    The surveyor who 'covers his !!!!' by recommending a specialist is doing the right thing. He is usually a general building surveyor and can't be expected to know about damp in detail. Lets face it - he will be sued if he doesn't and ends up missing a real problem.

    The big issue is getting accurate and honest advice for the buyer. There are many specialists who survey for a small fee and like me have proven over years that they issue a high proportion of 'no evidence' surveys. That is how a specialist builds up a good reputation so that his business can thrive on them.

    How can a buyer find a good one? Recommendation is best, but if not then membership of the Property Care Association is the best thing. Then, if there is a problem, get two or three quotes from PCA members. Make sure that you tick the box for Guarantee Protection Insurance when you place the order. That way your 20 year guarantee will be sound, even if the member's business fails in that time.

    All PCA members are bound by a code of ethics - they cannot lie - take commisions for referrels or give poor service without being subject dicipline by the PCA.

    Better still, as they are qualified, each have to carry professional indemnity insurance, just like your building surveyors do. None PCA membres who are not qualified can not get his cover - the insurers can't insure a potential idiot. This protects you if the surveyor makes a mistake.

    Dry Rot (CSRT)
  • edited 11 June 2010 at 11:55AM
    David_AldredDavid_Aldred Forumite
    371 Posts
    Part of the Furniture 100 Posts Combo Breaker
    edited 11 June 2010 at 11:55AM
    Some interesting points raised in the above posts and this is not the first time the subject of rising dampness and its treatment has arisen on the forum and neither is likely to be the last.

    For the consideration of the original poster (Franks) the following information is given:

    Electrical damp meters are designed to be used on walls as well as timber though the readings are most reliable when placed in wood given that usually the only thing within wood is moisture, though even some wood preservatives can cause false high readings. When used on walls these meters have a 'wood moisture equivalent' (wme) scale. Readings taken to timber with such meters indicate areas at risk of decay and similar surface readings to walls indicate areas of concern to be further investigated. Such readings however described do not on their own confirm rising dampness, a fact repeated within the British Standards.

    I am often asked does rising dampness exist or is it simply a myth and the answer is that in my experience it does exist and can occur within buildings to a considerable height. I was discussing a case recently where it had been proven to be occurring up to 2.4m in height which is considerably above the normal 1m high area of treatment typically undertaken by remedial treatment contractors.

    Another question I am often asked is how effective are chemical damp proof courses (dpc)? Well many such products have BBA certificates of Approval stating they are a means of controlling rising dampness and there are British Standards recommending how they should be installed. The latest types of chemical dpc are in a paste / cream form that can be hand pumped rather than injected under pressure into drillings within the wall (of which DryZone mentioned by others above is an example manufactured by Safeguard). The active ingrediant within the paste carrier however remains the same as some of the older type chemical dpc's so it is really only the method of application that has changed making it easier to see by those monitoring installation and much easier to handle / apply as there is no hazardous liquid under pressure.

    Chemical dpc's are a system that includes not only injection of the walls but also associated re-plastering to replace plaster contaminated with salts from the ground and for such plaster to hold back rising dampness that may still occur to some degree due to inherent limitations of the chemical injection process.

    I have dealt with a case where there was no original dpc within a party wall and one contractor injected a chemical dpc from one side of the party wall with associated re-plastering for their client (call this house / client A) which resulted in dampness becoming more apparent on the other side of the party wall in the other house (call this client / house B). Some time later the client in house B had a different contractor inject a chemical dpc with associated re-plastering. What followed next was dampness appeared on both sides of the party wall above the level of re-plastering and both clients / houses re-called their seperate contractors and both undertook re-injection and both undertook re-plastering.

    Some time later the dampness returned and plaster failed on both sides of the party wall yet again including the re-plastered areas that had each been re-plastered twice and re-injected twice. The party wall was solid common brickwork 9" thick with lime mortar. Laboratory analysis revealed that rising dampness had once risen to 1.5m high but was currently present to around 1m high and plaster was contaminated with ground salts on both sides of the party wall. One contractor was a small company who had done his work with the best of intentions and the other was a national company with a well established reputation.

    So we had a wall that had four chemical dpc's installed and had been re-plastered on both sides twice by fully trained contractors working to what they stated was their specification yet clearly rising dampness remained a problem as proven by appropriate laboratory analysis.

    The conclusion is that chemical dpc's do work in theory and in some cases to control rising dampness to a point that is perceived to be dry but because the material is injected blindly and there is no guarantee that it will fully penetrate all areas due to such issues as viscous fingering their effectiveness may be simply to partially reduce the height of rising dampness rather than fully prevent it to a point that is perceived as being acceptable despite the best efforts of the contractors installing them. Accordingly they remain inferior and far less reliable than simple traditional dpc sheet materials.

    So we have established that rising dampness can occur to walls where no dpc was included within the original construction.

    Of perhaps more concern is whether or not rising dampness is as common as those selling remedial dpc systems would have their clients believe within properties that are actually built with a traditional dpc, be that slate or bitumen and the justification for recommending such remedial dpc's where there is an existing traditional dpc.

    Well we know that electrical damp meters do not prove rising dampness and that such a problem can only be confirmed by laboratory analysis of wall samples. We know that there may be many reasons for high readings to electrical damp meters other than rising dampness be they condensation, dampness emerging from floors, contaminated plaster / substrate, decorative coatings, issues within cavities such as condensation saturating cavity insulation, debris within cavities bridging the dpc etc.

    A slate or bitumen dpc may crack with settlement of a property but they remain naturally relatively impervious materials. I have yet to pull a sample of slate or bitumen dpc from a house wall and be able to confirm by laboratory analysis that I can make capillarity (rising dampness) to any significant degree occur up through it including bitumen felt even when cracked.

    The amount of dampness that will emerge up through such cracks in a traditional dpc would in my experience be considered to be negligable by laboratory analysis of wall samples taken above such a dpc be it cracked or not and would not correlate with full wall lengths of dampness as often diagnosed by contractors in such situations such that any rising dampness component under such circumstances should be the last thing considered and not the first. In other words if you find high readings by electrical damp meter to lower areas of walls of a property built with a traditional dpc get your investigate hat on and go looking for other causes and resolve those before blaming the poor original dpc.

    Considering the vast majority of the UK housing stock is built with a traditional dpc, from the above it may be concluded that for true rising dampness to be a significant moisture source within properties built with a traditional dpc it is relatively rare.

    Given the fact that electrical damp meters do not prove rising dampness then it is also reasonable to say there is considerable scope for misdiagnosis of rising dampness to properties where a traditional dpc exists, especially from those inspecting for dampness relying on such meters where they are put under pressure to keep a company's workforce in business, or where they are provided with financial incentives to guess at such high damp meter readings being true rising dampness.

    I would hazard a guess that the number of remedial contractors currently treating rising dampness would fall dramatically if there works were limited to only installing dpc's to properties where true rising dampness was confirmed to be a significant moisture source.

    As with anything there are good and bad contractors as well as good and bad surveyors. The good contractors have to make a balanced decision based upon their investigation and consider their liabilities. That investigation should consider all moisture sources and I know a few contractors who do this very well and make appropriate recommendations to resolve what is readily apparent putting true dpc failure at the bottom of their list where they can see a traditional dpc exists and to monitor for drying down once such other issues are resolved before considering laboratory analysis for any rising dampness.

    We currently have a system whereby a Chartered Surveyor finds high damp meter readings and pushes the client into the hands of a contractor selling damp proof courses. That system given the above problems is in my opinion far from ideal and open to abuse. Such a contractor be they good or bad cannot prove rising dampness by electrical damp meter and when suggesting a new dpc is necessary takes nothing more than a guess for their own profit.

    Proven failure of an existing traditional dpc the house was built with is very rare indeed. That chemical dpc is injected blindly and even where the work is not done negligently and with the best of intentions there is proven evidence that even injected four times rising dampness can remain a significant problem to a simple 9" clay common wall lacking a traditional dpc, thereby the effrectiveness of such treatment will always be questionable even where the contractor does it as best they might.

    Hammer drilling to install a chemical dpc into every brick or mortar bed of fragile masonry is highly disruptive as is knocking off plaster which in both cases often causes cracking and loosening of the substrate. In addition some of the carriers used to transport the active ingrediant of the chemical dpc can break down the original and much more effective dpc the house was built with such as bitumen. Under such circumstances where rising dampness was not proven by the contractor it should be realised that they may well be open to a claim of damages and negligence from the client if there work is proven to have been unecessary.

    It is of little suprise that the public view the remedial treatment industry as a whole at best in a mess under such circumstances and at worse nothing but a cowboy industry, despite the good old PCA trying to please both its members (primarily contractors) and the public. Contractors being CSRT trained and a member of the PCA does not address the above basic problems with the current system, where the amount of misdiagnosis and dampness remaining within properites after remedial treatment is staggering. Dampness is such a vague subject having many many causes and lacking definate easy means of confirmation of rising dampness. It is not like seeing a broken window and stating obvious failure followed by obvious fully affective replacement that one can have 100% confidence in.

    Despite some good contractors out there such as Dampdaveski the industry remains open to abuse and until the RICS Chartered Surveyors either properly diagnose the problems themselves or recommend the clients to have an in depth independent inspection of the true cause of the problem by a surveyor specialising in such subjects who can then specify works contractors can tender for, rather than pushing them directly into those selling replacement dpc's be they qualified / honest or not, I do not see the situation improving.

    For the original poster (Franks) you may wish to read my other posts within the forum regarding dampness, damp meters, decay, cavity wall ties and cavity wall insulation, etc which may be of interest to you and hopefully give you a better undertsanding of such issues. Kindest regards to all, David Aldred Independent damp and timber surveyor.
  • GloomendoomGloomendoom Forumite
    16.5K Posts
    Part of the Furniture 10,000 Posts Combo Breaker
    There is some interesting info in this thread.

    My own experience is with a very old house with stone walls infilled with rubble and mud. When I was buying the house, the mortgage company's surveyor suggested that a damp proof course might be needed. My own surveyor, however, didn't see any significant problem that living in the house wouldn't solve.

    Based on the report by their surveyor, my mortgage provider decided to withhold £2000 (it was ten years ago) until the damp was treated. I did some quite extensive research and the general consensus of opinion was that, given the type of wall construction and the materials used, any damp proofing solution, short of rebuilding, would be very unlikely to provide worthwhile long term results.

    I took my findings, along with my surveyor's report, to my solicitor and asked him to proceed with the sale as I could find the withheld £2k from elsewhere.

    In the end, the mortgage company advanced the full amount and I've had no problems with damp.
  • dampdaveskidampdaveski Forumite
    529 Posts
    ormus wrote: »
    there is no such thing as rising damp.
    many yrs ago, the building research establishment in watford, built a house and filled its cellar with water. and waited. and waited.
    6 months later, guess what? no damp walls.
    ormus wrote: »
    thats not rising damp per se, its a faulty DPC and or poor construction.
    the main point is that all/most damp problems are caused by water ingress from outside.
    usually too high soil levels. or water entering the building from the roof/windows/cavity.

    Make your mind up.
    Theres no such thing as rising damp, it's a faulty DPC??
    For your information, orm it can take anything upto 8 years for a 'new' wall to be affected by 'rising dampness' in test conditions as the air pressure inside the pores and vessels of the brick is greater than the pressure of 'water rising up'

    Get some [STRIKE]gorm[/STRIKE] FACTS!
    The advice I give on here is based on my many years in the preservation industry. I choose to remain anonymous, I have no desire to get work from anyone. No one can give 100% accurate advice on a forum if I get it wrong you'll get a sincere apology and that's all:D
    Don't like what I have to say? Call me on 0800 KMA;)
  • edited 11 June 2010 at 3:07PM
    dampdaveskidampdaveski Forumite
    529 Posts
    edited 11 June 2010 at 3:07PM
    Dry rot and David make good points as usual
    there are discussion topics there that could last for weeks.
    Needless to say in my opinion with the terrible name the 'damproofing' industry has, the considerable efforts of the PCA (Property Care Association) in giving training not only to member companies BUT housing associations, local authorities etc who employ member companies can only be a good thing and in my opinion will improve standards etc.
    Only this week I carried out a house purchase survey for 'damp' solely because the RICS surveyor stated in writing that in spite of a chemical DPC being installed in the last 12 months he found rising damp with his electrical resistance moisture meter
    Half the reason the damproofing industry has a bad rep is because of the sheer incompetence and ignorance of RICS surveyors allow unscrupulous companies to do what they do!
    The advice I give on here is based on my many years in the preservation industry. I choose to remain anonymous, I have no desire to get work from anyone. No one can give 100% accurate advice on a forum if I get it wrong you'll get a sincere apology and that's all:D
    Don't like what I have to say? Call me on 0800 KMA;)
  • Hi all. Firstly a big thank you to all that replied!

    We did go ahead and buy the house, I'm now writing this reply from the living room of the house in question.

    The mortgage lender has imposed a £2000 retention on the mortgage loan based on the finding of the RICS surveyor. They require a specialist survey and diagnosis from a PCA accredited contractor.

    With this in mind I found a company that serve the North West called "Peter Cox". They have a team that spans the region and are also CSRT CSSW accredited too. I have a member of their team coming to survey the findings of the RICS home buyers survey this coming Monday so I'll let you all know how that goes. The survey is also free now because we own the house. Before we owned it, they wanted to charge ~£100 If I remember rightly? I'm guessing this is due to people using them for free to decide how bad things may be with a property before going ahead and buying.

    During the few days I've been in the property I thought I'd check out all exterior walls and the DPC line when I noticed that ALL the lower air bricks on the exterior walls were completely silicone sealed up!? Someone has basically gone around to all the lower air bricks with a tube of silicone and injected it into every hole in all the bricks - why would someone legitimately do that!? There are no air bricks fitted on the adjacent interior walls so I'm asuming that these blocked exterior lower wall air bricks are fitted to serve air-flow through the two skins of exterior and interior brick walls. It's also worth noting that the house has exterior air bricks fitted on the upstairs level and these ARE NOT blocked. The upstairs air bricks also have internally fitted vents unlike the exterior lower air bricks.

    I'll also note that there is a salty residue on some of the exterior bricks at the level of the blocked up air bricks and at this level, some of the exterior bricks have spalled.

    So it seems my RICS surveyor was correct, there does seem to be evidence of excessive moisture at skirting board level. I guess the damp specialist surveyor from Peter Cox will provide me with more information too.

    My questions are:

    1. Why would someone go to the trouble of purposefully sealing up all the lower airbricks on the exterior walls? I can only think of doing this when the walls are cavity insulated or if the guy who did thought he'd cure some cold draughts?

    2. Does this sound like a costly repair? The whole house has just been completely redecorated with wall paper so there are no signs of damp on the internal walls.

    3. Would simply drilling out the air bricks allow the moisture to slowly dry out without any possible need for a damp repair?

    I look forward to your replies, and I'll also update the thread once I have my report from the damp survey.

  • edited 4 August 2010 at 9:15PM
    Franks_2Franks_2 Forumite
    4 Posts
    edited 4 August 2010 at 9:15PM
    I've just been around to the neighbours house (semi-detached) and they have zero issues regarding damp. There air bricks are also operational and free-flowing.

    I'm going to check all of my external brick mortar tomorrow for signs of patched over drill markings. This could be a clue pointing at cavity wall insulation being injected at some point. This could be a reason why I'm having problems...
  • edited 18 November 2010 at 1:56PM
    Franks_2Franks_2 Forumite
    4 Posts
    edited 18 November 2010 at 1:56PM
    Just updating this thread for those who were following it.

    I had David Aldred who posted above to come over and survey the property. After initial moisture meter readings showing "high" levels, he did a carbide test from a drilled wall sample and the result was less than 1%. Anything over 5% is cause for concern. So yes, bone dry walls and no rising damp.
    I'm just angry at the fact a so-called professional company came over and did a "free survey" on the property before David did. They had recommended a full chemical DPC to be installed and plastering to be carried out at a total cost of just under £2000. I was suspect of their diagnosis as they only probed the walls and found the obvious high moisture readings - They did no carbide tests.

    Anyway, the results are in and the cause of my higher than usual moisture readings at skirt level is due to normal house settlement. The house has solid floors with an asphalt finish. This settlement has meant the walls have shifted slightly and left a tiny gap for absorbent wood/plaster to soak up any moisture at that gap and thus show "high moisture" readings when probed with a moisture meter. There is further evidence too with a small section of wet-rot skirt that has been painted over in the kitchen.

    The fix is simple and far from requires a full DPC. That actually would bear no effect and it's simply not necessary.

    I'm just glad I paid for an independent survey and didn't take heed of the advice by the surveyor who was affiliated with a DPC contractor.

    Thanks again David!
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