Need a Straight Forward System to takle the "So called Rising Damp?"

Discussion in 'Plastering and Rendering' started by Groovejet, 6 Nov 2021.

  1. Groovejet

    Groovejet

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    I've went in circles regarding approach to solving damp internal brick walls.
    Should'nt it be simple? But there's conflicting answers on every site.
    People saying, there is'nt such a thing as rising damp? That cement mortar screed is wrong? Then next post online will say, Cement render is correct! Ridiculous.
    I should be able to make my own educated guess after i've read all the procedures.
    But what makes me hesitate making a move to remedy the damp, is these posts all over the web are mostly from guys of many years experience in the trade.
    So is it a case that these guys are correct, but something in the procedure for defeating the damp goes wrong , thus rendering job unsuccessfull?
    My approach was going to be-

    Remove existing plaster 1meter high, treat with anti-sulfates. Brush on a tanking slurry ,2 coats. Then render using a lime mortar & a clean sand with SBR added. Then spray SBR coat onto render, dry then plaster??
    Ive seen injection systems fail & ive seen tanking fail.
    Im at a loss really.
    Any ideas welcome.
     
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  3. JohnD

    JohnD

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    find out where the water is coming from, and correct the defect.

    for example it might be one or a combination of bridged DPC, leaking drains or pipes, dripping gutters, blocked airbricks, wet chimney.

    tanking does not repair any of these faults. nor does silicone. nor render.
     
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  4. Notch7

    Notch7

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  5. Groovejet

    Groovejet

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    Yeh none of the above. The walls are internal walls, damp is rising and not from any secondry problems like gutters. Only chimney breast wall id say was because its not capped off. So like i mentioned im back to trying to stop the damp somehow. Its a older terraced house with no dpm. And alot of walls have salts bleeding through.
     
  6. JohnD

    JohnD

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    older than 1875?

    what town is it in?

    Do you mean the damp is round the chimneybreast?

    Does the water supply pipe pass under the house?

    Does it have wooden floorboards with a void beneath?
     
  7. Groovejet

    Groovejet

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    Late 19th century
    Stockton on tees
    Chimney is just 1 wall, this damp will be because chimney's not capped off,
    Water pipe will run from front street to back kitchen
    Downstairs is concrete floor
     
  8. sxturbo

    sxturbo

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    How old is the house?

    Are the walls coated in gypsum plaster or lime plaster

    What type of paint is on the wall, If lime plaster it needs to be a breathable paint.

    You may be looking at the wrong solution.
     
  9. Groovejet

    Groovejet

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    Yeh, not sure atm about plaster type. When i remove it ill know.
    Lime plaster needs a non vinyl paint yeh?
    I understand but i havent decided on my route yet. So im trying to gather all the info, like i said, people give so many wrong remedies. I want to get it right. Appreciate your input
     
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  11. JohnD

    JohnD

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    so there is a water pipe, more than a hundred years old, buried under a solid floor, running front to back of house?

    is there a water meter?

    do you think the house was built with a concrete floor, or was it added later? were there ever any airbricks?
     
  12. Groovejet

    Groovejet

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    good points. but all houses in street have bad damp, ive seen it plenty.
    ill check about meter, so i can check for passing.
    yeh i think house was built with concrete floor, but ill see if he has the house deeds.
    what bearing would new concrete floor make? Would it be bridging and creating a way for ground water to creep up walls?
     
  13. sxturbo

    sxturbo

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    It could, but also could be causing a lack of air flow.
     
  14. sxturbo

    sxturbo

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    It would need a breathable paint like a clay paint.

    Modern paints aren't breathable.

    My post is the correct way of fixing the issue, but it depends on other factors as John d has touched on with the floor.

    A quick and easy fix would be to out a damp proof membrane on the wall and then put plaster board over the top of that.

    I don't believe its the correct method as it's masking the issue and. It fixing it, but it may be what the budget can afford

    https://www.permagard.co.uk/advice/...at is a damp proof,the damp has been resolved.
     
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  15. JohnD

    JohnD

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    A new concrete floor with DPM (and insulation) can prevent water coming through the floor, but it will not prevent water coming up the walls, if they are so old that they have no DPC or the DPC is bridged.

    The floor and any hiding treatment will prevent water evaporating off, so will not reduce damp.

    if a concrete floor was added after the house was built, it may have been done to hide or "cure" damp, without addressing the cause. Worse, if there was a DPC, it may bridge it. Annoyingly, it makes it harder to find the source of water later. Water does not always come from pipes and drains, but it often does.

    A ventilated void enables water to evaporate off the brickwork, so the upper part will be drier.

    I can't help suspecting that when the house was built it was probably not built on a lake, so the water must be coming from somewhere.

    p.s.
    relevance of 1875 is that this is the year DPCs became compulsory in London. Other towns may have been similar dates. I don't know Stockton, but Darlingon has some good Victorian builds.
     
    Last edited: 7 Nov 2021
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  16. Godwasaplasterer

    Godwasaplasterer

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    take the bricks out a few at a time, install a modern dpc and replace the bricks.
    or inject a chemical dpc. i’ve had good results with both methods.
    tanking is a last resort and can cause other issues.
     
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  17. Groovejet

    Groovejet

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    Sorry , today i started job, its wooden floor, nor concrete, sorry.
    Also i found air bricks partially blocked on front and side of property,
    Main walls that are bad and have salts bleeding out are 2 chimney walls, and the adjoining hall wall to next door.
    Hall had ply panells on, and wall was soaking, ive removed plaster on all bad walls.
    How can i see the differance to lime plaster and gypsum? Walls were typical over 1" thick plaster.
     
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