Damp on chimney breast

Leif

I just realised that people here might know the answer to this one.

I have a chimney and fireplace in the sitting room. The wall is flush, and the back of the fireplace projects into the kitchen. I had an old boiler in the kitchen which vented into the chimney flue via a hole at head height. When a new boiler was put in, the old one was removed, and the whole in the wall blocked with breeze block and plastered over. I then had a stove fitted in the sitting room, with a stainless steel liner for the chimney.

Anyway, today I found damp patches on the kitchen wall, at the base of where the old hole was (there is also a hairline crack in the plaster). The patches are very obviously damp, and discoloured. What is going on, and what can I do to stop this? We have had almost continuous rain for a day, with some torrential downpours, as well as the usual heavy rain for ages.

I know from taking measurements that the builders opening is constructed separately from the kitchen wall. Not sure what happens higher up, but I assume two layers of bricks. I guess the builders filled the hole with breeze block, bridging the two layers of brick. Then damp got in and collected at the base of the breeze block, and wicked though to the other side.

But how can damp get in when it is lined? Or is the flue outside the liner still vented to the outside?

rustyboy21

Hi Lief

Could the kitchen have had a fire in there in the past? What I mean is that although it seems to be the chimney protrudes into the kitchen, it could have had the facility in the past to have a fre in it ( my house is like that) .

If so, you wouldnt be using the one flue, you would have 2 flues utilising the chimney breast. With the installer taking out the old flue when putting in the boiler, then bricking it up, if he hasn't sealed the flue at the top, you will be getting rain down it.

It is common to have 2 flue sitting side by side in one chimney breast.

Best thing to do, would be have a look outside at the chimney stack and count how many pots/cowls you have ,then look at how many rooms on that side of the house could have had fires in them in the past. If the pots work out the same amount of rooms, inc kitchen, that is your answer. You would need to put a cowl on the flue to stop raing coming down in future.

My house had 2 chimney stacks with 12 pots on, before I took one stack down. Can still have a fire in cellar and attic if I wanted.

Leif

Thanks Rustyboy21. There is one cowl, with a peaked hat on it, and another small 'thing' next to it. That could well be a cowl, as I did wonder what it was. I will check the measurements I did, as the protrusion into the kitchen is not enough for two fires, back to back, but they might be side by side. But I doubt it. This is a 1969 build. But what it might be is a separate flue for the boiler. So the builders should have blocked that one, and surely they should have left a small vent in place to ensure the flue remained dry? It would not surprise me if they madea mistake, as they were somewhat slapdash as far as the other work went. And I will ask neighbours, as there are many other bungalows built to the same design as mine (same builder).

Leif

It looks like there is a second flue that was used for a gas boiler, with a cowl on top. Perhaps wind allowed rain into the side vents on the cowl, or the pointing needs attention. Time to go on the roof.

rustyboy21

Leif wrote: »

It looks like there is a second flue that was used for a gas boiler, with a cowl on top. Perhaps wind allowed rain into the side vents on the cowl, or the pointing needs attention. Time to go on the roof.

Good luck Leif. Hope the wind stays down. Been beautiful up here today 20 dg. Wind has got up now, dog wouldn't go out lol.