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Damp Proofing Question
Damp where chimney breast was removed
We have a damp problem in a mid-terraced house where the chimney breast has been removed in the living room (don't know when it was removed). Highest level of damp is at the height of a dado rail, a few inches below and above. Using a wood damp measure meter stuck into the plaster, the reading was off the scale (OL). On top of the bricks there is white plaster covered with vinyl paint then wallpaper. Plaster crumbles when it's lightly scraped with a scraper. It's very different to the pink plaster used on the rest of the wall. Below the plaster on top of the soaked brick there appears to be soot.
Can anyone suggest what could be causing this?
Which tradesmen do we need to call to look at this?
As this is a party wall, do the neighbours have to agree for any work to be done?
Is this sort of thing that building insurance would cover?
Sounds like when the chimney was taken out they did not get rid of the soot properly - this is what the black is. Also the chimney was internally damp then plastered over now the soot and efflorescent salts are coming out the salts are white and bubble up the paint, you need a damp proof plasterer to hack off affected area, clean the brick work up, then render with sand and cement with additives to stop salts coming through.
Answered 29th Apr 2013
I concur with plaster works answer but would like to add that the brickwork may also be contaminated with ammonium sulphates which absorb atmospheric moisture (humidity) and would require neutralising. The bubbling paint is a build up of pressure behind causing the paint to lift away. The paint is non permeable I assume.
Salt neutralisers are available "over the counter" and, if carried out correctly, treatment can be carried out by any reputable plasterer/builder, it doesn't necessarily have to be a "specialist" although should a guarantee be required then that would be the route to take.
Answered 30th Apr 2013