Chimney removal | Soot bleeding | Damp as well

[brucesmith1980]

Any help greatly appreciated. I had the chimney removed in the dining room of my victorian Terrace. The builder chased it out, blocked the inlet with concrete blocks, filled it, then skimmed it. The soot bleed through the plaster. He said to apply white gloss to to stop coming through. I used a zinsser product to stop the bleeding. Now it's autumn, the stains are still coming through and I've noticed damp as well? How do I resolve this please. Rip the wall off and start again, add an air brick? We put a chimney cowl on the chimney to stop water. There are two pots so I'm guessing the chimney is shared with the neighbour. We put the cowl on the right pot though. Thank you for your help.

 

[Wayners]

If you still have a chimney opening then you need a vent to allow air flow, or you will get condensation which will cause staining.
Is that's what's happening here because opening wasn't blocked off?

 

[Mottie]

We removed the chimney stack right through in our first house. It was the fashion at the time - we were all doing it. I had a mate who was a plasterer. Before he came round and plastered the wall, he made me take all the soot off of all the bricks with a comb chisel. He said if I didn’t, no matter what I did, the soot would eventually bleed through. It was hard work, but it never bled through.

 

[ree]

OP,
Presumably, the void left in the party wall when the chimney breast was removed was totally "filled in"?
What is on the other side of the wall? The neighbour's matching chimney breast?
Why not ask the neighbour if you can have a look?
When the fireplace and chimney breast was removed was the back wall (the party wall?) thoroughly cleaned of soot - a hard, dry scrubbing brush is good to use.
Are any upstairs fireplaces blocked off - are there any signs of damp upstairs?

Based on the info so far then there's no need for GF ventilation or any kind of Zinnser.
You could maybe get 20 to 30 years stain free if you hack off the gypsum plaster, and render with a mix of 3:1 sand & NH lime render.

 

[brucesmith1980]

Thanks for the feedback. The chimney is still open. We put a vented cowl on it but I guess we need to add a vent at the bottom of the wall? He did block the chimney up with concrete blocks to stop flow but I guess it's abit of a mess. Either way gonna need to take off and remove all the soot before working out have to stop the damp as well!

 

[Wayners]

Yeah. Vent at the bottom to get air through.
Let it dry.
Stain block and paint

 

[ree]

OP,
Your descriptions are difficult to understand.
You have chimney breasts on each floor and in the loft - when the loft c/breast pierces the roof it becomes the chimney stack. C/breasts contain flues.
Your pic shows your party wall - your party wall was the back wall of the c/breast flue.
Typically, your Victorian terrace party wall will be 4" thick. - so where and how is the "chimney still open"?
Can you post a pic showing where you intend to vent?
The signs of damaged plaster in the photo are possibly soot based chemicals passing through the party wall from the neighbour's flue? Or, as above, from poor soot cleaning?
You say you "have to stop the damp" - where is this damp?