Moisture around chimney

[panlondon]

Hi, we had our loft space converted and since the plastering & painting of the chimney breast there is a permanent moisture issue in the center of the chimney breast. It ranges between 22-29% and hasn't improved for the past 5-6 months. The moisture expands from the top of the chimney breast on 1st floor bedroom and pretty much all the way to roof height in the loft bedroom above. There is no moisture downstairs in the ground floor chimney. The chimney was little wet while the roof was constructed, as some rain penetrated. The flashings have been checked and all looks perfectly fine. I was thinking that there might be some leak from the central heating but that wouldn't explain why there is water to the very top of the house by the ceiling.

I was told that there might be an issue with salts as a results if burning fossil fuel which penetrated the chimney and now attracts moisture from the outside. To be fair I think if I was to repaint the wall I will probably never notice anything again but I am worried that there is an underlying issue. My builder said that he doesn't know what the problem might be but he suggested that he could repaint it or even plaster it etc. The wall has been painted with emulsion paint which I don't know how much it helped if there was a moisture issue.
Do you think that if I leave the wall as it stands the problem will eventually go away (even after 2 years say). I don't want more hassle in the house to be honest/ redecorating or plastering again. Does anyone have any advise please? Thank you.

 

[KenGMac]

panlondon, good evening.

Sorry no immediate magic bullet answer, but a couple of questions?

1/. What age is the property [Victorian? perhaps?]
2/. Are the chimney pots at roof level capped + ventilated? [all of them?]
3/. Are all of the fire places blocked of? if so is there a vent into the room from that[all of the] fireplaces?

Ken.

 

[panlondon]

Hi, thank you and sorry for delay. The house was build in 1937. There are 3 internal chambers as part of same chimney. All have a cap with ventilation. Nothing is blocked completely. There is 1 vent into the room on 1st floor correct. Thank you again.

 

[martin hill]

Hi There. Is it just damp to the touch or do you have condensation on the breast. Being worse in the loft.

 

[panlondon]

The chimney breast is exposed at ground floor level and no moisture there. Then it goes to around 22% at the top of first floor and 22-28% in the loft level. Chimney outside has 3-4% thank you!

 

[KenGMac]

panlondon, good evening, again.

OK another question?

The flue vent in the first floor, is the vent actually clear? if you hold a thin tissue against the vent does it get drawn towards the vent, or blown away from the vent?

Why the above? I have seen "several" vents on walls where the debris falling down the internal of the flue has actually blocked the vent.

Another way of testing if the vent is "clear" [that is at least 90%] air spaces able to allow air flow. is to poke a very thin probe into the vent openings to see if there are any obstructions in the inner side?

Ken.

 

[panlondon]

Hi Ken,

Sorry forgot to reply. There is definitely good aeration, tried the tissue. It has actually improved, so obviously I should encourage the air aeration and not close the air vent at the bottom. Thank you again.

panlondon, good evening, again.

OK another question?

The flue vent in the first floor, is the vent actually clear? if you hold a thin tissue against the vent does it get drawn towards the vent, or blown away from the vent?

Why the above? I have seen "several" vents on walls where the debris falling down the internal of the flue has actually blocked the vent.

Another way of testing if the vent is "clear" [that is at least 90%] air spaces able to allow air flow. is to poke a very thin probe into the vent openings to see if there are any obstructions in the inner side?

Ken.

 

[opps]

The chimney breast is exposed at ground floor level and no moisture there. Then it goes to around 22% at the top of first floor and 22-28% in the loft level. Chimney outside has 3-4% thank you!

Just so that you know, it is common to see higher results on plaster that had been previously wet, even if it is dry now.