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Treating rising damp on internal party wall

Discussion in 'Building' started by sam78759, 12 Oct 2021.

  1. sam78759

    sam78759

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    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
     
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  3. JohnD

    JohnD

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    Who told you it is rising damp?

    A few silicone injection salesmen.

    Does the water supply pipe run under the floor?

    Is it a concrete floor?

    what is on the other side of that wet wall?

    Why is there a pier sticking out of that wall?

    How big is the wet patch?

    have you lifted the floorboards yet to look underneath?

    The chocolate-coloured plaster is modern, and very wet.

    The shape of the wet patch on that pier suggests the source of water is at the front of it.

    Also

     
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  4. sam78759

    sam78759

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    The damp was spotted when we were redecorating, and the 'rising damp' was the assessment from a few damp surveyors we've had around (who we're aware may be salesmen!).

    We have wooden flooring and the wall in question is a party wall which we share with our neighbours.

    The wet patches themselves go slightly above the sockets in the first photo, and probably about a couple of feet high up the chimney breast in the second photo.

    We haven't lifted the floorboards yet as we don't have the tools to do so - would this allow us to identify the problem more clearly (and therefore find the appropriate treatment)? All of the damp surveyors so far have been opposed to lifting the floorboards and suggested it won't help.

    If it really is rising damp, are there other treatment options besides the injections they're quoting?
     
  5. Harry Bloomfield

    Harry Bloomfield

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    You need to find a way to access that under floor area, to properly assess the cause of the damp in those walls. You should also speak to your neighbour, to see if they have a similar issue. Most damp specialists are salesmen, keen to sell expensive damp treatment - better to dix the cause, rather than the symptom.
     
  6. RandomGrinch

    RandomGrinch

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    As JohnD says, many (except those in certain damp proofing companies!), consider rising damp to be a myth.
    There is nearly always another cause, be that penetrating damp, leaks, condensation etc.

    An interesting viewpoint can be seen here:

    https://www.heritage-house.org/damp-and-condensation/the-fraud-of-rising-damp.html

    ...also interesting is why the surveyors are saying lifting the floorboards won't help. If the wall were to have rising damp, the first things to rot would be the floor joists and boards!
     
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  7. RandomGrinch

    RandomGrinch

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    Just re-reading your post, is what we see in the photos a partially closed in fireplace?
    It first appeared to me as a doorway through the wall.
    A slightly wider photo may help, and if it is a fireplace, that may help to explain things! :)
     
    Last edited: 12 Oct 2021
  8. jacko555

    jacko555

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    How long have you lived there?
     
  9. sam78759

    sam78759

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    We moved in a few months ago
     
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  11. jacko555

    jacko555

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    I agree with JohnD and Harry etc.

    There's a source of water. Looks like the previous owners replastered and decorated. They must have known about the damp.

    Lift the floors. See what's on the other side of the wall etc
     
  12. JohnD

    JohnD

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    Chimneybreast, eh?

    When you take the floor up, see if there is a hearth slab just beneath.
     
  13. JohnD

    JohnD

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    Wouldn't help them if you discovered the real source of water, maybe.
     
  14. tell80

    tell80

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    sam78759, you have rising damp on your chimney breast and in the recess to the right side.
    its possible theres rising damp in the recess to the left of the chimney breastand in the fireplace opening itself but its not yet shown itself.
    you will have to remove allthe skiting boards near any damp. Lifing the raised flooring inside the fireplace might show more damp.
    knock off plaster back to brick to a line about 1000mm above the floor.if the corner beads are metal see if they are rusting.
    Did the mortgage survey mention damp?
    if itspossible someone should go under the floor and have a look at thingsaround the chimney breast.

    the wall is a party wallso have the neighbours complained of damp?
     
  15. mrrusty

    mrrusty

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    The giveaway is it's a chimney breast. First, are all the chimneys cowled. It is surprising the amount of water that gets down an open chimney, and guess where it ends up - at the bottom around the fireplace. Secondly if the fire was used in the past extensively, the bricks around it will likely be salt poisoned to some extent through the reaction of building products with combustion gases. These salts are hygroscopic, attracting moisture from the room causing "damp". This is exactly the situation I had.

    1) cowl any open chimney pots, including next door's if it's a shared chimney!
    2) scrape off all paint and let it dry as much and for as long as possible.
    3) if you don't want to strip the plaster as well to reinstall salt resistant, then a coat of damp seal paint will help to keep the room moisture away from any salts in the wall - this has worked about 95% for me.

    Do check for any leaking pipes etc, but I bet it isn't. And IMHO rising damp in the middle of a house is just an opportunity for snake oil salespeople
     
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  16. sam78759

    sam78759

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    Thanks for all the replies - very helpful.

    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)?
     
  17. RandomGrinch

    RandomGrinch

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    Hi,

    If you can post a couple of pics of the outside of the chimney, and pots etc. And again a wide photo of the fireplace, this may help us narrow down the problem. You may need a builder/roofer to fix the ultimate cause of the problem! :)
     
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