Wet interior wall, chimney stack on other side

Soldato
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Hi,

We have a wall that's attracting condensation in the house, on the other side of that wall is a disused chimney stack that's been sealed at the top and has an air brick at the bottom

I know it's condensation because the colder it gets the worse it is, my question is what to do about it.

What I don't understand is the wall on the outside can't be that cold, it has an extra layer because it's got the chimney stack mounted to it, there is also air flow in there because of the air brick so what best to try first?

I can cover the air brick to prevent cooler air entering to see if that improves it if it does I can see if I can get it filled with insulation?

Anyone else had a similar issue and managed to resolve it or understand the science behind it?

Thanks
 
Soldato
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So your house is a semi? The chimney stack should be mirrored on your side? One therefore assumes your chimney has been removed?
 
Associate
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Is water getting down inside the chimney?

If it's capped at the top and air brick at the bottom that doesn't allow for airflow, it could be damp cold air with no way of escaping.
 
Soldato
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Chimney has been removed and capped yeah, not sure why

Not sure there is any point having the cap removed, birds will get in there and we're having a Dormer loft conversion next year so I need to speak with them about it

I think I'm going to invest in a dehumidifier until the loft conversion is underway and I'll speak with them about the chimney cap
 
Soldato
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Faulty flashing or covering to the remaining stack leading to water penetration and capillary action of the water soaking into your side. Perfectly normal.
Repairs needed - although these are likely now the responsibility of the neighbour
 
Soldato
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When I moved in my whole lounge was damp, carpet rotten etc. Survey and damp survey said penetrating/rising damp from outside walls..

Once I got the place stripped back I found the blocked up chimney breast was wet to the touch which was tracking down to the floor. Moisture getting in down the chimney which survey had said needed repointing. But also Vinyl wallpaper had been keeping the moisture in and the air vent was totally blocked with dog hair, dust etc.

Cleaned out the air vent and didn't replace the wallpaper and it's been absolutely fine. Haven't needed the chimney repointing
 
Soldato
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Faulty flashing or covering to the remaining stack leading to water penetration and capillary action of the water soaking into your side. Perfectly normal.
Repairs needed - although these are likely now the responsibility of the neighbour

I'm not sure what you mean, this isnt the main chimney to the fireplace in the lounge, it is a redundant chimney that is at the rear of the house and isnt shared with our neighbors. Its really not related to rain, its definitely condensation forming on the interior wall.

https://www.diydoctor.org.uk/projects/damp-chimney-breast.htm

Some possible reasons here. Most likely being build up of condensation from a sealed stack with no airflow.

Thanks, just read it. I just don't get the science behind it though because surely the air in the Chimney stack is warmer than the outside air.

When I moved in my whole lounge was damp, carpet rotten etc. Survey and damp survey said penetrating/rising damp from outside walls..

Once I got the place stripped back I found the blocked up chimney breast was wet to the touch which was tracking down to the floor. Moisture getting in down the chimney which survey had said needed repointing. But also Vinyl wallpaper had been keeping the moisture in and the air vent was totally blocked with dog hair, dust etc.

Cleaned out the air vent and didn't replace the wallpaper and it's been absolutely fine. Haven't needed the chimney repointing

Interesting, I'll get pokey with the air vent at the bottom of the stack and see if its blocked. If it is blocked and air getting in helps alleviate the issue then I'll look to get the cap at the top vented. Again though I dont understand how letting cold air in would resolve it because that would make the wall colder.
 
Soldato
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Yeah the vent at the bottom of the stack is completely blocked with what looks like soot and sand, poking it feels like its just moving it down I think I will need to remove the air brick to get it all out but it could be stacked half way up the house for all I know!

Also the top is under the soffits so it might not be capped, it might just vent into the soffits. Looks like a visit to the loft eaves is in order, gutted there are spiders the size of face huggers up there.

Edit - Just removed one of the circular vents on one side of the chimney stack in the back bedroom and there is an old birds nest completely blocking the soffit vent and interior of the soffit!
 
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