Chimney Condensation Mystery

[leeds1971]

I wonder if any of you have had experience of this:

The house we are renovating (built in 1844) has had the heating and water switched off and all the pipework taken out since December. There is no chance of a water leak.

We are getting condensation on both sides of a chimney breast. Both walls affected are internal walls (although one side of the chimney is an external wall). The chimney has many years ago had the fireplaces taken out and blocked up. Both rooms affected are well ventilated.

One wall has wallpaper on it and the water builds up on the paper until it trickles down the wall. The wallpaper is still firmly on the wall.

The central heating boiler flue used to go out from the basement up the through the chimney, but this has been off since December.

It's always the same chimney, yet other blocked up chimneys have no problems at all.

This problem has been happening in all weathers - any help would be appreciated

 

[agbagb]

Well ventilated rooms. Happens in all weathers. No pipes to leak!

I agree it's a mystery.


Try drying off an area with a heat gun/ hair dryer. Then tape / stick some polythene to it. This should confirm if it really is condensation.

 

[stuart45]

Redundant chimneys can suffer from condensation if the flues are not ventilated properly, but the chimney breasts can also have a problem with hygroscopic salts in the plaster. These can attract condensation at a relatively low R/H. It usually happens near the ceiling on upstairs rooms as this is where the salts are more likely to be in the plaster.

 

[Lime]

Has any mould formed on the damp/wet areas?

 

[Andrew Bodenham]

I'm wondering if weather could be playing a part here.
Before this week it's been really cold. If the chimney is open / vented at the top then a mass of dense cold air may have dropped in and accumulated in the flue, cooling the masonry. Now suddenly we've had an introduction of warm humid air, which will be permeating your rooms. When it meets your cold walls condensation occurs. This is phenomenon is known as warm-front condensation and is common in structures with high thermal mass.

You don't say if the flue is vented to the room. Ideally it should be cowled at the top and vented at the bottom to allow a free flow of air through the flue. If the top is open then rain penetration may also be a factor.

Maybe time to get up a ladder and see what's going on at chimney level.

 

[angrybird]

I wonder if any of you have had experience of this:
Hi Leeds1971 in having the same problem whith my upstairs lounge chimney breast,I too am renovating the house(1840),i've had it 3 months and the house hadn't been lived in since last July! have you checked the lead flashing as this is my next job to do? yesterday I also noticed my stone stairs to be covered in condensation and today the stone wall in the kitchen!(which is underground) I think its because we had that very wet spell and now a warm spell its like the poor old house is sweating ! I also think it could be lack of heating as there is nothing to "dry " the moisture up! but as my new Rayburn is parked in the hall we are a long way off the "heating" stage :?


The house we are renovating (built in 1844) has had the heating and water switched off and all the pipework taken out since December. There is no chance of a water leak.

We are getting condensation on both sides of a chimney breast. Both walls affected are internal walls (although one side of the chimney is an external wall). The chimney has many years ago had the fireplaces taken out and blocked up. Both rooms affected are well ventilated.

One wall has wallpaper on it and the water builds up on the paper until it trickles down the wall. The wallpaper is still firmly on the wall.

The central heating boiler flue used to go out from the basement up the through the chimney, but this has been off since December.

It's always the same chimney, yet other blocked up chimneys have no problems at all.

This problem has been happening in all weathers - any help would be appreciated

 

[leeds1971]

Thanks for the advice guys.

I think I may have solved it (finger's crossed).

The basement is damp and there was a hole in the chimney breast down there where the boiler used to vent out.
The natural draw of air up the chimney could have been pulling up the cold damp air.

I blocked up the hole, dried up the water on the chimney breast and so far, two days later - no water condensation.