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Damp on internal party wall

Discussion in 'Building' started by SJRSJR, 19 Apr 2016.

  1. ^woody^

    ^woody^

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    The main cause of damp to party walls is chimneys. And damp walls at floor level are more likely to be from damp coming up from the hearth and breast, rather than damp coming down the flue.

    There is no DPC at the bottom of a chimney, and no DPM under a hearth.
     
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  3. SJRSJR

    SJRSJR

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    Is there anything that would cause it to flare up in the hearth area, it's been fine for years? I mentioned that the house had been empty for a spell but no amount of heating since has eliminated it. Could that have triggered it?
     
  4. Justintime4t

    Justintime4t

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    Have your neighbours had a DPC installed on the adjoining wall recently?
    If so, perhaps the moisture that was coming up at an acceptable level for years is now just coming up your side only - including the 'natural' damp from their side which goes up your side as their DPC pushes it that way?
     
  5. ^woody^

    ^woody^

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    Seasonal ground water changes. This can be unpredictable and often leads to the "why didn't it happen before" question.

    It could also have been damp for a while, but not so much as to be noticeable.

    Or leaking drains can increase local ground water
     
  6. SJRSJR

    SJRSJR

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    I know this post is dragging on...

    I finally bit the bullet and got rid of the laminate flooring to see what might be below. From two previously cut access points the void below is 20 inches deep and seems dry and not musty and the joists look fine.

    After yet another chemical injection quote I decided to get an independent damp survey (£800!) and called a RICS registered company this morning. We talked through it all on the phone and he was very helpful but even he said that my likely solution will probably the chemical injection/waterproof slurry (Vandex).

    As I understand it damp takes the path of least resistance which means to avoid it springing up somewhere else, won't I need to get all four walls of the living room done (which will be a nightmare as there are built in cupboards)? Is masking the symptoms really an acceptable solution? Incidentally my neighbours haven't had any works done.

    (By the way the surveyor complimented me on my knowledge which was mostly learned on this forum - thank you )
     
    Last edited: 23 Sep 2016
  7. vinn

    vinn

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    Dont worry about the thread dragging on.

    Did you actually pay £800 for a Survey?

    The answers to your predicament are advised above but to give you a little more food for thought:
    Its a simple matter to remove the fire & surround, & lift the floor at the c/breast, and lower the soil, & repair woodwork in the fendered hearth area.
    Knock-off plaster & renew in S&L as advised above.
    Drill & injection is simplicity itself.
    Make good a new wood sub-floor in the dropped hearth area.

    Vandex & similar might drive the damp up and through the wall? It might also be blown off (with its covering render). But thats a personal opinion.

    DIY Doctor & Trusted Tradesmen etc. sites are recommendations to be avoided.
     
  8. SJRSJR

    SJRSJR

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    Thanks for the reply, all that makes sense. No I haven't commissioned the survey yet, we just talked on the phone. Maybe I'll save my money and put it towards the cost of the job.

    Have had another local damp specialist round this morning, he says the same - injection and waterproof render- one and a half walls £2600.

    Where the built in cupboard is dry lined he said to leave it and forget about. He doesn't think the damp will automatically move to untreated areas but 'it might'. I don't understand this.

    Attached is a picture of the hearth area, do you know what material it is? It's reading damp. If I dug it out how could I damp proof it? Won't it just rise through the brick surround? Thanks
     

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  9. vinn

    vinn

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    Good, in your case an Independant isn't needed.
    AAMOI, be cautious about using the "Damp Meter"

    I'm confused with the two different c/breasts that keep appearing or being referred to.
    Is the last hearth shot the c/breast of concern or are both showing damp signs?

    The front hearth is concrete, & you can crack it out with a breaker.
    If you are handy, a carefully judged few whacks with a sledge hammer will splinter the concrete - start near the back not near the flooring.
    The fire place must also be opened up and the back hearth cracked out as well.
    Once you have done that & cleaned up all debris then come back here.

    Be alert to any gas pipes or elec cables in the area.
     
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  11. SJRSJR

    SJRSJR

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    I put this photo up because the other still has the slate hearth on top. Both are showing damp - it spreads from them outwards towards each other but doesn't meet. I know to be wary of taking meter readings as absolute measurements but because they reduce the further you go isn't safe to assume the relative aspect of it?

    When you say 'back hearth' do you mean the base of the fireplace within the chimney breast? Thanks.
     
  12. Cat2019

    Cat2019

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    I know this post is two years old, but your issue is exactly my issue. I’ve hacked the old concrete hearth out that was in the floor, and opened up completely the other chimney breast.

    All damp still there, and surveyors saying rising damp with a chemical DPC, they said no need to hack the plaster just the bit around the chimney breast that we have just opened up.

    I’m hoping the original poster can give us an update on how they got on, did you get the DPC done and did it work?

    Thanks in advance.
     
  13. JohnD

    JohnD

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    Do these "surveyors" happen to work for companies that sell chemical injection?

    There aren't many houses left that were built without a DPC, and chemicals will not cure water leaks. Neither will they ventilate subfloors whose airbricks are blocked.

    We had another poster recently who dug out the damp material under his hearth so the area could be ventilated and dry out.
     
  14. Cat2019

    Cat2019

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    There’s deffo no water leaks from any pipe works under the floor in that area as none run along that side nor in their house and doesn’t appear to be any damp patches on the floor underneath (we have suspended floors) and some sort of concrete base where we worked.

    next door on the party wall have no damp issues there side either.

    The company is a family run business and there surveyours are in house and do all sorts off work not just Damp related stuff, very good reviews on check a trade, that’s as much as I know for the company. I did get two quotes and both said rising damp - chemical DPC. One wanted over 2k and the 2nd no where near that price and issue a 20 year warranty.

    The airbricks ain’t blocked and there have been extra ones put in many years ago to allow increased ventilation (the only issue I know previously from a burst pipe from the neighbour they had to get the wood treated? There’s prob more but he denied any knowledge, so who knows if his telling porkies or not)

    However when changing the floor boards as they were no good we established that 8/10 joists were rotten and had to be replaced as they was just no good. One of the joists run along the old hearth base and was wet most likely from rising damp, we made sure we put new damp course down on the new joists and lay DPC on the hearth bricks as well as removing the wet material off the party wall below what looks like the DPC and it’s still showing the same High readings?

    Surly if the company offer a warranty, and I still have wet walls, what actually happens?

    Do party walls contain DPC? It’s a 1950s built property.


    Thanks in advance
     
  15. JohnD

    JohnD

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    read the terms. Their "remedy" might just be to apply more chemical.
     
  16. Cat2019

    Cat2019

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    Thanks I’ll have to call and ask as they haven’t sent me no terms and conditions within the quote it’s self.
     
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