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Damp 1st floor gable end (chimney) - contradictory solutions

Discussion in 'Building' started by pineapple, 22 Jun 2015.

  1. pineapple

    pineapple

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    The cottage I'm renovating was neglected and largely unoccupied for 25 years. There is damp on the 1st floor gable end in line with the chimney flue. We have hacked off all the plaster and are repairing any structural issues which might have caused the damp - ie no flashing on the chimney stack. Meanwhile we are letting the place air and dry out - the wall already feels a lot drier.
    A damp and timber specialist has suggested fitting a vapour barrier (looks like a sort of rigid bubble wrap) but leaving a gap of about 2 inches at the top and bottom. That way, he says moisture will escape and the wall will continue to dry out.
    The builder who is doing most of the renovation disagrees saying that would be more appropriate for a damp basement. He is proposing to dry line the wall.
    Do I need a vapour barrier and would either solution deal with the salts now present?
     
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  3. ^woody^

    ^woody^

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    Both those solutions are the same thing - dry lining.

    You need to determine the actual cause of the dampness - rain coming down the flue, or condensation moisture coming from the unused flue. You could potentially then just deal with the cause and replaster after applying a sealing/stabilising solution to the affected wall.
     
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  4. theprinceofdarkness

    theprinceofdarkness

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    Its a convention to put an air vent into an unused chimney stack to allow a little air to flow up it to dry it out. Dry lining is hiding the problem, if the moisture gets worse your joist ends will rot through. I would leave the walls unplastered for as long as possible, it will help to locate the source of the damp and allow it to dry out.
    Frank
     
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  5. pineapple

    pineapple

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    I'm waiting for the stove fitter to get up there and have a proper look while he is fitting a liner and a new cowl and flashing (there is none at the mo). There is one chimney stack and one visible pot - we don't know if there was a bedroom fireplace in addition to the lounge fireplace below and if there is something capped off in addition to what we can see. Will be leaving the wall with the plaster off for some months (at least) and getting the lounge fireplace going to get some heat there.. I'm told there are salts on the wall surface. Do these need neutralising?
     
  6. ree

    ree

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    OP, you are more or less reproducing your post to the Roofing Forum earlier this month. In that thread you were given advice which you did not acknowledge neither did you thank the contributors.
     
  7. pineapple

    pineapple

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    Sorry I'm normally pretty good about thanking people but I've got so much going on I forgot about the lead dpc post. So shoot me I'm imperfect. Just revisited and remedied! In my defence it started out as a specific question about the lead dpc recommendation and this was about the wall treatment but a bit of mission creep in the other thread it seems.
     
    Last edited: 24 Jun 2015
  8. ^woody^

    ^woody^

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    One pot = one fire place. Fire places will not share flues or pots
     
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  10. pineapple

    pineapple

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    Thanks. The builder thought there might be evidence of a second flue on the first floor wall plus it would have been the norm in houses like this to have a bedroom fireplace though from ground level you can definitely only see one pot. Anyhow we are meeting at the property tomorrow and I'll try to get a clearer idea of what he is proposing for the wall. So far we have taken off all the plaster (along with the woodchip and a foil backed lining) to the 1st floor gable end wall and the damp area seems to be drying out.
    Edit: If I sound like a bit of a numpty at times it's because I am! I'm a retired female with relatively minor DIY experience :rolleyes:
     
    Last edited: 24 Jun 2015
  11. ree

    ree

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    OP,

    Given your circumstances here's a couple of things that you might do:
    Unless you actively have a builder working on the property then wait and take advice from here before hiring anyone.
    Try and place, and keep, all relevant subjects on one page.
    Answer all queries - they are for your benefit after all.
    Post pics of everything.

    Ref the possible second flue - the gable pic shows the pot to be on the left hand side of a wide stack.
    If there were only one flue then the pot would be centred on a narrow stack.
    If the plaster is off the bedroom gable wall then it should be relatively easy to locate any blocked off fire opening.
    Any investigator on the roof should provide you with pics of the stack & flaunching.

    All flues should be swept and smoke tested.

    Its possible that sooty flue chemicals are leaching thro the chimney breast brickwork, and presenting as damp on the decorated plaster surface.
     
  12. pineapple

    pineapple

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    Cheers. There is a builder involved already actually. Plus a HETAS reg stove/chimney guy - just waiting for his quote for a new stove, a liner, new cowl and chimney flashing.. Have already had the flue in use (from the lounge stove) swept and tested. Are you suggesting I have the other flue opened up and checked?
    Will be posting pics tomorrow hopefully.
     
  13. pineapple

    pineapple

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    Hi folks. Sorry been left without a connection during home move.
    The stove fitter/chimney guy has fitted soakaways and flashing (there was none). Since then there doesn't seem to have been any more water ingress and the damp seems to be drying out. He advised, as suggested here, leaving the wall unplastered as long as possible and eventually using lyme plaster followed by renovating plaster.
     
  14. ree

    ree

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    What are the "soakaways" that you refer to?

    3:1 sand & lime plaster followed by a remedial skim (Limelite ?) will be required.

    Ref. my post above: "sooty chemicals" can be faintly seen following the flue line on the pic of the gable render.

    FWIW: what, if anything, has happened with the other suggestions that were made here, and in the roofing thread?
     
  15. pineapple

    pineapple

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    As I was saying I have been left without a connection. I am relying on intermittant and extremely slow public wifi which is almost non existent in this remote area. It has taken me nearly an hour just to get to this point Ree and to navigate to the other threads and respond properly would take me another couple of hours. Frankly I don't think you are worth it. You seem to have issues - in fact you really stand out from other posters. There are other less aggravating sources of help which is a shame as otherwise this is a brilliant forum.
    Have a go at someone else why don't you. I'm out of here.
     
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