Leak from previously removed chimney

[Maya_161]

Hi, I’ve recently purchased a Victorian flat and noticed damp in the kitchen. After removing the wallpaper and some of the wall (which came off fairly easily), I’ve uncovered that this is where the fireplace would’ve previously been (it’s been removed on both floors and there is support in the loft). The top of the chimney stacks haven’t been capped and so I’m planning on having ventilated caps installed. In relation to fixing the wall, does this anyone have any recommendations on what needs doing? Does any cement need removing and breathable materials need installing? Are air bricks on the inside wall required? For context this is on a party wall to the flat next door.

 

[Stevers]

Yuk! Looks like gypsum plaster reacting with salts and damp. Reinstatement in NHL render/plaster would have the huge advantage of being sulphate resisting. Sulphates being what contaminates flues, not only from any fireplace in that room, but from any further down. I used an NHL render and plaster on a basement chimney breast that had previously been 'damp proofed' with cement and gypsum and was pretty ugly too, the improvement afterwards being remarkable. My flue was still there though with gas liner and I ventilated that to outside as close to the register plate as I could get. My builder didn't hold with ventilating upstairs flues, but did religiously vent any of our blocked off downstairs ones. All of the pots on our disused flues have clay 'elephants foot' cowls which allow a bit of air flow, but keep the rain out.

 

[Maya_161]

Yuk! Looks like gypsum plaster reacting with salts and damp. Reinstatement in NHL render/plaster would have the huge advantage of being sulphate resisting. Sulphates being what contaminates flues, not only from any fireplace in that room, but from any further down. I used an NHL render and plaster on a basement chimney breast that had previously been 'damp proofed' with cement and gypsum and was pretty ugly too, the improvement afterwards being remarkable. My flue was still there though with gas liner and I ventilated that to outside as close to the register plate as I could get. My builder didn't hold with ventilating upstairs flues, but did religiously vent any of our blocked off downstairs ones. All of the pots on our disused flues have clay 'elephants foot' cowls which allow a bit of air flow, but keep the rain out.

Hi Stevers, thanks a lot for the response very used to understand how you tackled the issue - I was also planning on going for lime replastering. I’m yet to uncover if there is a liner or not. Did you have to add a vent of some sort at the bottom to provide extra ventilation or was using NHL render and plaster sufficient in your case?