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Blown plaster on kitchen

Discussion in 'Plastering and Rendering' started by Merlin5, 11 Aug 2020.

  1. Merlin5

    Merlin5

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    Hi guys. I better give some background first.
    My house is an old edwardian era terraced and there's always been a bit of a damp problem in the kitchen along only one of the two exterior walls. In 1987 when I bought it I had a DPC installed which didn't really seem to be much good. I had the whole kitchen refurbished in
    2012, everything taken back to the brickwork, rendered and plastered.

    In the last year or so, some of the plaster on that one wall either side of the door leading to the outside has bubbled and blown. So I need to remove it.

    Because it's only one wall, it makes me think the damp was penetration through the bricks and not rising damp. I've had some leaks fixed from drainage pipes above which may have been the cause as I could see damp areas on the external bricks. I don't think it's the drains because they're situated in front of parts of the wall that haven't blown inside.

    So, if I bought some brick waterseal, can I paint it onto the internal bricks to block water penetrating new render and plaster? Or, if when I remove the plaster I was to find the render is ok and didn't need removing, can I seal that instead?
    Or how about I just paint the outside wall with brickseal?
    And if so, does it need to be the really expensive stormdry stuff or would most sealers be sufficient?
     
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  3. bennymultifinish

    bennymultifinish

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    can we see pics of the inside and outside
     
  4. Merlin5

    Merlin5

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    Sure. Just taken some shots of the inside wall either side of the door to the patio, and some shots of the outside of the same wall either side of the door. It's really just the edge area of the inside wall on the left of the door and a little further in on the other side.


    20200812_143633.jpg 20200812_143816.jpg 20200812_143422.jpg 20200812_143404.jpg 20200812_144159.jpg 20200812_143440.jpg 20200812_143352.jpg
     
    Last edited: 12 Aug 2020
  5. bennymultifinish

    bennymultifinish

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    can we see the lintel above the door and any windows directly above?
     
  6. Merlin5

    Merlin5

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    20200812_161432.jpg 20200812_161457.jpg
     
  7. Merlin5

    Merlin5

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    I'd like to thank bennymultifinish for all the advice he's given me. Posting lots of photos has fixed the problem.
     
  8. bennymultifinish

    bennymultifinish

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    the remedial pointing looks fresh.
    as does the pvc window directly above the area to the right inside issue.
    as does the ‘new’ infill brickwork replacing what looks like a window to the right inside.
    why someone would inject brickwork as opposed to the mortar line is anyones guess so I won’t go there.
    my only input would be i’d fit 4 single brick vents , 2 either side of the door preferably under dpc level but looking at your ‘plinth’ that would be difficult , so just above dpc would do.
    and expose the brickwork inside to see if its dry which i suspect it is.
    looks like they cemented the inside with no salt inhibitor in .
    to stop the recurrence of such salts in future the whole wall , or at least immediate affected area would need hacking off up to 1 metre from floor and re rendered using a waterproofer and salt inhibitor.
     
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  10. bennymultifinish

    bennymultifinish

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    soz. don’t live to answer q’s on here. but hope this will help
     
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  11. Merlin5

    Merlin5

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    Thanks. If you suspect the bricks to be dry, are you implying that it's not water coming through the bricks from outside, and therefore it's rising damp? The builder at the time told me they'd put a waterproof PVA solution into the render (or bricks I'm not sure which).

    So I'd need to remove the skirting boards, right? I've got a bag of coarse sharp sand, a bag of cement and a plastering trowel will that do for the render?

    I've never ever done rendering or plastering though, I'd probably do it badly. Should I attempt it or not? What waterproofer and what salt inhibitor and what ratios to mix into the render? And what ratio of sand and cement for the render itself? And then what about the plastering?
     
    Last edited: 13 Aug 2020
  12. bennymultifinish

    bennymultifinish

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    waterproof pva doesn’t contain salt inhibitors. afaik.
    it doesn’t look particularly damp however , you may have an element of rising damp particularly if they drilled the bricks internally and not the mortar joint, like outside. however it wouldnt rise more than a metre at worst and certainly wouldnt climb up a corner bead.
    the ratios of waterproofer/inhibitor you need depend on the product you buy.
    you could use brick sealer on it for your own piece of mind and it may help .
    i’d strip the damage back to the brick inside first to see whats going on.
     
  13. Merlin5

    Merlin5

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    Thanks Benny. The thought of rising damp depresses me, lol. I'd much rather it was some other cause. And from what you're saying, particularly that rising damp wouldn't climb up a corner bead, it sounds like there's a chance it's not rising damp.

    Yeah, I don't know if they drilled the bricks internally or externally. I always thought DPCs were drilled externally and then injected. Either way, I've heard that chemical DPCs don't work?

    I'll do what you suggest and start taking the plaster and render off. Unless the render seems solid and intact, maybe I can leave it? If I used brick sealer, is there a particular brand you'd recommend that you know works well, and do you mean seal the bricks on the outside or the inside?
     
  14. bennymultifinish

    bennymultifinish

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    seal externally. can’t recommend one as I don’t use them.
    chemical dpc’s do work. they’re usually injected into the mortar course.
     
  15. ted456

    ted456

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    Merlin5,
    You have rising damp.

    Is the kitchen floor solid?

    What was the render you say was used in the kitchen - was it a mix of sand and cement - was it applied to all wall surfaces?
    Have you carefully examined all the kit walls for damp signs eg behind units & appliances and under the sink? Likewise the door frame sealing.
    When stripping the old plastering off the walls you must remove all of it to 300mm past the last damp damage signs.
    Check wood skirtings for rot on the back.
    The metal corner beads will need cutting off and replacing with plastic corner beads that do not rust.

    Can you locate the original DPC line on the outside wall surface?
    To the right of the door there are three levels of injection holes - all of them useless.
    To the left of the door the course of DPC injection holes are also useless.

    The rendered plinths need to be completely removed - they are helping moisture to rise & penetrate , & if there is an original DPC they are bridging it.
    The plinths, the Aco drains & the attempts at injecting a DPC are all attempts to prevent your damp problems.
    There's a bit of a smeared on attempt at pointing thats not working - another attempt to stop a little penetrating damp possibly?

    After doing whatever then post a couple of pics will you? But dont start any sealing, rendering or plastering.
     
    Last edited: 16 Aug 2020
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