Hi All. We moved into an very old stone house last June and after a week or two noticed a few small damp/wet patches on the plastered and emulsioned bedroom wall along the line of the chimney breast. The chimney has the oil fired central heating flue running inside it. The wet patches continued to grow and are now many and Big!. Some have little brown stains in the middle, but no mold. We have had a roofer to renew flashings, tiles, cement around the base of chimney and a cap on the top, all to no avail. The gable end is very exposed to the weather but the pointing looks good. Attic area above is dry. I have since tried a dehumidifier on 24/7 heating on and off (but the radiator is on the opposit wall) Windows open/closed. No difference. The room is large and quite cold I am thinking of having the radiator relocated the chimney breast area...what do you think? Any suggestions greatfully recieved.
Damp on Chimney Breast
- Thread starter sugrist
- Start date
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Is the chimney brick or stone? Cement flashings are not the best and your roofer should have pointed this out and tried to install a lead flashing, and tray if possible.
Have the stains got worse since capping the chimney off? If so then it is probably due to poor ventilation / circulation of air in the stack.
If the patches only appeared after a couple of weeks of moving in, had the previous residents recently decorated to hide the problem or are you doing something drastically different to them?
Did you buy the property? If so then to have a damp treatment specialist survey it before purchase is always a good idea; likewise goes for electrician and gas engineer / plumber.
Have the stains got worse since capping the chimney off? If so then it is probably due to poor ventilation / circulation of air in the stack.
If the patches only appeared after a couple of weeks of moving in, had the previous residents recently decorated to hide the problem or are you doing something drastically different to them?
Did you buy the property? If so then to have a damp treatment specialist survey it before purchase is always a good idea; likewise goes for electrician and gas engineer / plumber.
Thankyou for your reply
The chimney is all stone.
The new flashings around the base between the chimney and the roof look like lead.
The new cement is just around the pot on the top.
What is a tray please?
The rain cap is perched on the top with a gap for ventilation
Yes, It was newly decorated I think they must have hidden the problem some how, but may be we are are more frugal with the heating!
Yes we bought the property, and paid for a home buyers survey, but the problem was not spotted.
What do you think about the radiator idea?
The chimney is all stone.
The new flashings around the base between the chimney and the roof look like lead.
The new cement is just around the pot on the top.
What is a tray please?
The rain cap is perched on the top with a gap for ventilation
Yes, It was newly decorated I think they must have hidden the problem some how, but may be we are are more frugal with the heating!
Yes we bought the property, and paid for a home buyers survey, but the problem was not spotted.
What do you think about the radiator idea?
What do you think about the radiator idea?
May well temporarly solve/hide the problem, if the weather stays good,it's not the answer though. is it?
What did the H Survey man say when you told him?.
May well temporarly solve/hide the problem, if the weather stays good,it's not the answer though. is it?
What did the H Survey man say when you told him?.
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Fossil fuels produce nitrates and chlorides which go up the flue and some stay on the flue walls. Fires also produce water vapour which condenses higher up in the chimney. In time this takes the salts through the flue and into the plaster inside the room. As these salts are hygroscopic they attract moisture from the atmosphere. This can occur with an R/H as low as 50%. This may be the problem here. The R/H in the room may be too low for mould to form.
Thankyou so much for all the very helpful suggestions .
If the hydgroscopic salts are causing the probelm, how would you go about rectifing this?
We havent contacted the suveyor who did the home buyers report as we didnt think there was any point, do you think we should? Is there any come back for this type of thing?
At the moment I am trying to keep the humidity in the room as low as possible and they seem to be fading, but it hasnt rained for a while...
If the hydgroscopic salts are causing the probelm, how would you go about rectifing this?
We havent contacted the suveyor who did the home buyers report as we didnt think there was any point, do you think we should? Is there any come back for this type of thing?
At the moment I am trying to keep the humidity in the room as low as possible and they seem to be fading, but it hasnt rained for a while...
If salts are the problem you need to hack off the plaster and re-render using a sand/cement mix with a waterproofer additive. You can have a sample of plaster tested for salts if you are unsure. It is also possible that you have penetrating damp as well, so its best to make sure that everything on top is sound.
As regards the surveyor you would have to decide whether you think he was negligent or not. I am not a surveyor so I am not really a good judge of this. It could be that on the day of the survey he didn't get a high reading there with the meter. Does the plaster sound hollow in that area?
As regards the surveyor you would have to decide whether you think he was negligent or not. I am not a surveyor so I am not really a good judge of this. It could be that on the day of the survey he didn't get a high reading there with the meter. Does the plaster sound hollow in that area?
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