Treating rising damp on internal party wall

Discussion in 'Builders' Talk' started by Sam78759, Oct 12, 2021.

  1. Sam78759

    Sam78759 New Member

    We've been told that we have rising damp along one of our internal party walls (Victorian terraced house - c.100 years old) - see attached photos taken during recent redecorating.

    A few damp specialists have been over and they've all recommended injecting the wall with a DPC paste and getting the affected walls replastered. From what I understand, the DPC paste will block further moisture from rising and the replastering will get rid of contaminated plasterboard which can attract further moisture.

    This seems to only stop further moisture from rising, rather than treating the actual source of the issue though - is this typical treatment for rising damp? Are there other options which would more effectively target the actual source of the problem?

    Damp 6.jpg

    Damp 4.jpg
  2. Joe the Plumber

    Joe the Plumber Screwfix Select

    There is no such thing as 'rising damp'. Look under any canal bridge for proof. 200 years of constantly sitting in water and it ought to be dripping right from the top, if it existed. It doesn't.

    The first, and only thing you need to do is locate and deal with the SOURCE of the water, whether it's from leaking pipework, ground water, drainage, etc, etc.

    All 'damp proofing' firms, unless they do as I've just suggested, are nothing but cowboys.

    Plenty of sensible advice about damp here:
    GRH, CGN and Pam Fussey like this.
  3. stevie22

    stevie22 Screwfix Select

    Rising damp is real. Bricks are porous (to a greater or lesser extent) as is mortar and water will be drawn up though there becomes a point where gravity will balance the capilliary forces and the water won't rise any further.

    That is basic physics and no amount of nay-saying is going to change that. There will always be water in the ground: your garden won't be green otherwise!! We don't install DPMs & DPCs for fun.

    I totally agree honest damp proof companies are rare animals and that leaks and drainage problems need to be ruled out, as does condensation which is another common cause of damp.

    Injected DPC works fine and is an easy DIY job.

    Do you neighbours have a problem?
    Jord86 likes this.
  4. Sam78759

    Sam78759 New Member

    Thanks both for your replies. We are going to chat with our neighbours later to see if they have the same issue.

    It sounds like looking beneath the floorboards to assess the condition/problem is a sensible next step. I'm not sure we have the right tools/expertise to do this ourselves - what sort of tradesman should I be looking for to remove the flooring, identify the source of the problem and get it fixed (given none of the 'damp specialists' I've contacted so far are willing to do this)?
  5. Bob256

    Bob256 Member

    While you say that it is a party wall, the bit of the wall that seems to have the biggest problem appears to be forward of the rest of the wall. Is it a chimney breast we are seeing with a closed off fireplace? If so, is there any ventilation in the chimney breast. If not, I believe that damp can build up, though I have no experience of seeing it and whether it could take the form that you are seeing.
  6. Pam Fussey

    Pam Fussey New Member

    I'm guessing the original dpc has deteriorated along the bottom of wall. I think in an ideal world a plastic dpc should be chased into the lower brickwork (if that's possible?)
    We spent over £7000 nine years ago with a well known Damp Proofing company because we have a similar, but more extreme damp issue, on our already renovated 1880's house. They injected & replastered walls & put up impermeable membrane on other walls, as well as apparently using salt inhibitor and 'renovation' plaster, and we haven't been able to decorate since that time! They never looked for the actual cause of our damp, just said it was "rising damp & salts". Today it is in an even worse state Unfortunately my finances are seriously lacking so I have taken to stripping the walls back to brick just to get the crumbling plaster off. The membrane should never have been used on this age of house, as all it's done is seal moisture into the wall, which will eventually be detrimental to the structure of the building. Damp patches & salt started to reappear within weeks and they just offered to re inject and replaster which seemed pointless so we lived with it. New damp patches started to appear on adjacent walls to those membrane,(it just moved the problem on) & new patches appeared near the dividing stud walls and it turns out that because the membrane is breached between the two rooms (behind the door frame against wall), I'm guessing the original dpc has deteriorated on our internal solid wall, so the moisture is escaping out along the easiest route, along the door frame. I say I'm guessing as unfortunately in 2004, the whole floor was covered in thick concrete when it was converted from a large 5 car garage to living areas, so to find the source would mean chopping out the concrete against the walls, digging down to original brick foundations and adding a new dpc which is out of my budget. On another of our internal walls with suspended timber floor with a very similar look to yours, I created a hatch to look under the floor and saw that an old bituman dpc has deteriorated, which is allowing moisture to move through the bricks. If those investigations had have happened before, I don't think I'd have had half of the stress I've had for the past 17 years. Everything went wrong when cement render & gypsum plaster was used on our old home and the damp proofers made the problem even worse!
    If I give you one piece of advice it's... If you own an old house, please use Lime plaster on your walls and repoint bricks with lime mortar/ lime render, it will save you so much stress! Ideally, your neighbour should do the same.
    I'd also check if there are airbricks in the external walls under your timber floor and that they are clear and open to allow for good ventilation , and check that the external floor level doesn't allow for water to get in through the air bricks.
    Definitely check the sourse of the moisture & rectify that first though, as injecting and replastering will not solve the problem in an old property.
    Joe the Plumber and GRH like this.
  7. chillimonster

    chillimonster Screwfix Select

    rare to see non-trade give a like so not surprised to later read of your experiences
    and knowledge. Hope it comes good in the end for you.
    Pam Fussey likes this.
  8. GRH

    GRH Member

    I agree with Joe the plumber, there is no such thing as rising damp. Old houses like yours are built with brick and lime mortar, which allows the wall to breath and water to evaporate. Modern building materials - especially Portland cement prevent this, and when used for repointing, cause spalling of the bricks. That looks like gypsum plaster on the wall, if it is, that is another cause of damp - should be lime. I recommend you take the time to look at the website JoeTP gave to help you understand the problem and causes before trying to solve it.
    Joe the Plumber, Pam Fussey and CGN like this.
  9. Pam Fussey

    Pam Fussey New Member

    Was that comment aimed at me, Chillimonster? If so, thanks!
    It's a real shame that there aren't more plasterers/ renderers & general builders that are trained in working with lime & treating old properties correctly. Trying to find them is like looking for Gold dust where I live!
    Sam78759, I hope you have an easier time than I have in getting knowledgeable tradespeople to help you out. Good luck!
    Joe the Plumber likes this.
  10. CGN

    CGN Screwfix Select

    Rising damp is a load of old cobblers. The moment these walls are hacked off to brick and exposed to air they start drying out.
    Joe the Plumber, Pam Fussey and GRH like this.
  11. GRH

    GRH Member

    I can attest to the truth of that, having recently done just that. Of course, if the wall is external, make sure the pointing is sound (and is lime) and bricks are not spalled/damaged other.
    Pam Fussey likes this.

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