TREATED DAMP STILL THERE

Discussion in 'Building' started by wossie6, 26 Oct 2005.

  1. JayS

    JayS

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    Thanks Thermo! :)

    I didn't say it necessarily has to be due to a failed DPC. Bridging due alterations, etc. done over the years is probably more likely I think. No?
     
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  3. TexMex

    TexMex

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    Aha, now I find the reason for Sofus's other post. I'll not go over it all again, but Rising Damp DOES occur, but all things being equal, it doesn't just suddenly appear.

    Wossie, the thing that worries me with this post, is you seem to imply that you had Cavity wall insulation installed to cure a damp problem? Unless your original damp was purely condensation, it was doomed to fail.

    You may be confusing two separate processes. There are injected DPC systems (that squirt water resistant resin into the fabric of the brickwork). These should not fill the cavity. They merely fill the pores of the bricks and mortar with impervious chemicals.

    There are also injected cavity wall insulation systems. These inject various products into the cavity to create thermal insulation and have nothing to do with damp prevention (other than perhaps, reducing condensation). The cavity is all that is needed to prevent the moisture getting across from the outer skin to the inner.

    In a cavity wall, the internal skin should be completely isolated from external sources of water. At the top, you have the roof and guttering, the outside face of the skin is protected by having a cavity, and finally there is a DPC in the bottom of the wall to prevent the water rising. These are the areas you should be checking to remedy your problem.

    There are many problems that can cause water to get from the outer skin to the inner. Sloppy bricklayers may drop mortar down the cavity. If this comes to rest in dollops on the wall ties, this will cause a breach. A more common problem is where great wodges of the stuff piles up at the bottom of the cavity. If the top of this is above DPC level, it not only breaches the cavity (giving water a path from the outside to the inside skin), but also allows rising damp a path past the DPC. (See my amateur artistic attempts below). If you have any of these problems, surrounding the offending material with insulation will have no effect whatsoever. This sort of problem can be inherent in buildings from day one, or may be created by poor working practices in other works (such as window replacements or even the fitting of gas flues!).

    [​IMG]

    Problems at the roof can also be the cause. The trouble is that, water doesn't usually just follow gravity straight down. Where you have a leaky roof, it will quite often follow the structural woodwork downwards and then percolate down through the wall. It's even possible for this type of fault to show no obvious effects on the top floor and only surface somewhere lower down at ground floor level.

    I recently had a severe leak in my living room (downstairs). The wife thought I was mad going out in the pouring rain to locate the problem, but it turned out to be an issue with the gutter. The bedroom immediately below the problem showed no dampness at all. If I hadn't witnessed it in progress, I doubt I'd have found the cause so quickly.

    You still don't seem to have mentioned if this is a recent problem or if it has been present since the house was built.

    BTW. The worst cases of damp are quite often caused by leaky plumbing. As I say, due to the porous nature of brickwork, it is not always obvious where the problem lies. Applications of water treatments can make the diagnosis even more difficult. The water becomes trapped in the brickwork and soaks through to other areas until it finally finds a permeable surface to rear its head.

    Personally, if you have a cavity wall, I wouldn't dream of applying tanking or other barrier methods above the DPC. These type of systems belong in Cellars or solid wall constructions. Far better to find the root cause of the problem and sort it out.
     
  4. Softus

    Softus

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    Marvellous stuff TM. You could be a teacher with that degree of understanding and clarity of explanation.
     
  5. empip

    empip

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  6. joe-90

    joe-90

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    I agree. I've had the same experience with the gutter BTW.


    joe
     
  7. Nige F

    Nige F

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    But Tex still maintains that rising damp exists. Must be that academics agree to disagree :rolleyes:
     
  8. Softus

    Softus

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    Hmm. Maybe. I'm still digesting the recent information, but I'm open to the possibility that TM is correct (not that I've ever found him to be wrong).
     
  9. joe-90

    joe-90

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    So do I. This house was dripping before the walls were injected.


    joe
     
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  11. wossie6

    wossie6

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    I had two people say that rainwater (not dampman i must say OUT LOUD)could have been seeping down through a solid 9 " exterior brick wall thats tied into problem area.So i bricked it back level as it was stepped and dropped a coping stone on top,alls well,its dreid out a treat now,just waiting for some decent rainfall now.Condesation still a problem tho, will look at this soon.
     
  12. Softus

    Softus

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    wossie6 - it sounds like you're saying that the problem was caused by falling damp? Not rising damp after all?
     
  13. wossie6

    wossie6

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    its a bit hard to say as of yet as the ground has not had a decent soaking for a while,time will tell ;)
     
  14. Softus

    Softus

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    My breath is now fully bated in readiness of further news :eek:
     
  15. KonradFischer

    KonradFischer

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    Oh, how much wise words referring the rising damp! :idea: Perhaps some additional remarks are allowed:

    Rising damp does not exist in masonry, because there is no capillary transport between fine pored stone and rough pored mortar, even if the stones are in water for a very long time.

    [​IMG]

    [​IMG]

    This means also there is no capillary transport possible between the exterior stones and the interior joints.

    If you injects chemical dpc in watery solution, you will moisture up your masonry and mostly the chemicals will split off hygroscopic active salts, which will take up humidity all the time. The injected water will be stored in the wall for a very long time. It needs about 700 days to dry out a wet 50 cm brick wall without further heating. What to do with moistured walls you'll find a lot of details here: How to get rid with damp in buildings

    Good luck!
     
  16. Softus

    Softus

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    Hello Konrad

    You seem very sure of your facts, so I would like to invite you to comment on another topic as well.

    Please click here to go to the other topic.

    If you have any reference to a scientific study that substantiates your comments, I would very much like to read more about this subject.
     
  17. KonradFischer

    KonradFischer

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    is a big deal all over the world. So I like it to awake the interest of another point of view. My building and planning experience since over 20 years under responsibility as architect learnt me not to distrust the good old craftsman, whose buildings stand better in our landscape than any new ones.

    So, Softus, all the scientific sources 'against' Rising Damp I have (or nearly the most of them) you can find quoted in the important sentences on the link. Parts are a text I published in building mags.

    On the german link you will find an enriched and oftenly updated info to the same topic.

    And naturally I have posted to the thread you gave me.

    Thank you for interest!

    Konrad

    Rising damp a hoax?
    Schwindelei mit "Aufsteigender" Feuchte

    Look and see: no rising damp at all over the joint (Pic 1) and the tide zone (Pic 2). The white layer on the surface of the harbour wall is a idiotic hydrophobic seal clever salesman could sell the stupid experts in the harbours building office. It is damaged by algues and blocks the drying of rain, which comes in in spite through cracks in the plastified seal.
    [​IMG] (1)
    [​IMG] (2)
     
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