I have a damp patch that extends from the top left front of the chimney breast, round the side and onto the (cavity) wall to the left of the fireplace. It runs down the wall from the ceiling about 2ft. Many years ago when i moved here i spotted this damp and had the chimney re-rendered and the flashing replaced. This seemed to cure the problem although i still got damp readings from the plaster, the walls did not feel wet.
At the time the building was a bungalow, but recently i had the roof removed and the existing walls extended upwards to form a 2-storey house. I also demolished the upstairs chimney breast that was now part of the bedroom and stuffed a piece of fibreglass insulation in the flue beneath the floorboards.
A few months ago, i noticed that the damp patch had returned and water was actually forming a drip down the wall. Since then i've been more vigilant in venting the room and the patch doesn't get wet but still feels very damp. The weather seems to have no bearing on how damp the patch is, and the outside wall is rendered, apart from a single course corbel between the old and new build.
Can anyone please tell me exactly what the problem and remedy might be? My guess is that salts in the plaster from the original defective flashing might be causing condensation in that area, possibly compounded by the extension work and/or blocking the chimney off.
Also, I'm about to have freebie cavity wall insulation injected into the lower half of the property, but i'm worried that this might complicate the damp problem and/or compromise the 80 year-old wall ties.
Any helpful comments would be appreciated.
At the time the building was a bungalow, but recently i had the roof removed and the existing walls extended upwards to form a 2-storey house. I also demolished the upstairs chimney breast that was now part of the bedroom and stuffed a piece of fibreglass insulation in the flue beneath the floorboards.
A few months ago, i noticed that the damp patch had returned and water was actually forming a drip down the wall. Since then i've been more vigilant in venting the room and the patch doesn't get wet but still feels very damp. The weather seems to have no bearing on how damp the patch is, and the outside wall is rendered, apart from a single course corbel between the old and new build.
Can anyone please tell me exactly what the problem and remedy might be? My guess is that salts in the plaster from the original defective flashing might be causing condensation in that area, possibly compounded by the extension work and/or blocking the chimney off.
Also, I'm about to have freebie cavity wall insulation injected into the lower half of the property, but i'm worried that this might complicate the damp problem and/or compromise the 80 year-old wall ties.
Any helpful comments would be appreciated.