Hi
I live in a mid terraced house built in the 1880s. I bought the house 5 years ago and have had a continuous problem with damp in the spare room upstairs/down into the dining room downstairs where the chimney breasts have been removed. The damp gets much worse when it rains and is leaving a track of damp on the wall where the flue will be, all the way downstairs.
We have had the leading, flashing, pointing and ridge tiles replaced. The bishop pots have been taken down and replaced with chinamans hats all of which has cost us a few hundred pounds each time. A few months ago we had the whole roof re-slated (at a cost of £2k) and we still have the problem. I really struggle to get the roofers to return after I tell them it hasn't worked and have to get someone different each time.
I really don't know what else to do and are considering removing or lowering the stack now as a final option - which again will be very expensive and has the potential not to be a solution. Any other suggestions would be very welcome.
many thanks

if the chimney breasts have been removed why didnt you remove the stack on the roof too (hope it is supported well) then you would have no problems at all

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Mike
http://rebuildingatimberbungalow.blogspot.com/
any advice welcome

Hi
Thanks for replying so quickly. The chimney breasts had already been removed when we bought the house and the survey didn't detect any signs of damp.

So it sounds like the chimneys have been removed from downstairs, but they remain upstairs in the bedrooms.

Is that correct?

If it is correct are there any vents in the chimney breasts?

If not that could be the cause of the problem. Damp could of got down the chimney, but can't be drawn out properly as there is not enough air flow, so the venturi effect of the wind blowing over the chimney pots can't suck out the moisture.

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DIY | Donnas dream house

There are two rooms downstairs and two bedrooms upstairs. The chimney breasts are still present in the front room and front bedroom but both have been removed from the downstairs back room and back bedroom - there are no vents.

If it's a shared flue, it could be coming down the neighbours side

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As you have already said that you have chinamans hats fitted, I'd fit some vents into each of the chimneys (in the bedrooms), so that the chimneys can draw out any moisture.


where the chimney has been removed on both levels you can also remove a single brick from the stack in the loft, which will also help the chimney draw out the moisture.

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DIY | Donnas dream house

It's not a shared chimney so I think we'll give the vents a try next, thanks for your advice.

Sorry, I've just spoken to my husband and it is vented through a couple of bricks being removed in the loft.

It could well be caused by the soot in the original chimney (now removed) having been plastered over. It can cause a chemical reaction with the plaster and looks just like damp. My brother got called to a house where there was what appeared to be a rather large damp patch on one wall. After hacking the plaster off, he discovered there had been a chimney breast (which had been removed). The plasterer had just bonded and skimmed over the soot , after brushing the majority of the loose stuff off.

When organic material such as wood and coal are burned, the deposits within the soot ie. sulphates and ammonium salts eat into the mortar and masonry.

These contaminates can be hygroscopic, in other words they can attract moisture from the air.
When it rains the moisture content within the property can increase also, so the contaminated area will become wet.

If all of the above suggestions fail, then you will have to hack off the plaster to the chimney breast area, isolate the exposed masonry with a cementitous slurry and a 3:1 sand cement render.

You can then skim the area with finishing plaster.