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If wall is damp does that mean plaster isn't waterproof?

Discussion in 'Plastering and Rendering' started by ToolbeltDandy, 31 Dec 2015.

  1. ToolbeltDandy

    ToolbeltDandy

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    My mum has issues with damp walls. They've been injected twice but still the walls are damp, some areas appearing darker than others and some walls only detected as damp using a conductivity-based detector. My understanding of the treatment that should have happened is that a chemical mixture was injected into holes drilled into the walls and the walls were then plastered with plaster containing a waterproofing additive up to a height of 1.2 metres. If the walls were plastered with plaster containing a waterproofing additive then I would not expect to detect damp in these regions of the wall. Is my reasoning correct? Is it reasonable to say that the plaster composition was not correct?
     
  2. stevethespreader

    stevethespreader

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    What type if walls? Solid or cavity brick or stone? What was the walls replastered with? And the walls only show up as damp with a damp detector?
     
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  4. ToolbeltDandy

    ToolbeltDandy

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    Hi. The walls are solid brick. The house is part of a row of cheap terraced houses built in around 1910-1920 in case that is informative.

    I only have a cheap Draper damp detector and haven't attempted to ascertain dampness by any other method.

    We don't have accurate hygrometers. We have the readings 68%, 65% and 32% from three adjacent consumer clock/weather stations but I'm not sure that they're at all reliable. We have a Challenge 415/9029 dehumidifier extracting approximately three litres per day (rated performance is 10 litres per day at 30 C and 80% RH).

    There are no visible signs of dampness on the walls except in the kitchen where it's very visible due to the darkness of the damp patches.

    I'm not sure what the walls were replastered with. I think it was done by the same people who did the DPC though. The first time they did it, salt came through one wall but that went away after their second visit. This was a few years ago though.

    There are no signs of black mould though.
     
  5. stevethespreader

    stevethespreader

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    You may have condensation on the walls where the walls are solid they will be cold and warm air and moisture from inside will be hitting those cold walls forming condensation , sometimes damproofing external solid walls may not be a good idea as there is now a barrier to stop the condensation from moving or escaping through the walls
     
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