Wet Chimney Breast

[SH4RKY]

Quick bit of background.

I live in a 1850s Stone Cottage on Clee Hill, Ludlow. The house has had various (fairly poor) extensions and modifications carried out over the last 30-50 years. These I will come to at a later date/post perhaps….

But this post is about the Chimney. I noticed some mould and wet walls in the bedroom around the chimney breast a while back. Wanting to strip back and refurbish the upstairs, I didn’t think twice about hacking a load of plaster off the walls to see what the problem was.

Found wet walls. Obviously had been like this for quite a while, but the inch thick gypsum plaster was probably doing a decent job of hiding it. But it didn’t really dry out and shortly after that, during some heavy rainstorms, I found water running down the walls. Long story short - the leadwork around the chimney was shot. The chimney cap was also found to essentially consist of a couple of slabs and some sand.

So replaced the lead and the cap, replaced the pot, and tried a little bit of repointing.

Still had some water running down the Chimney face inside the roof/bedroom. Checked and the leadwork looked fine, but maybe I messed up. In frustration I added some lead sealer/mastic stuff in any gaps or joins. Sealed any cracks, gaps in cement cap. And have recently painted the exposed brickwork with Stormdry.

Now I don’t get running water down the chimney breast internally. But the bricks on the breast and in the bedroom are still damp. I can run a dehumidifier that drys their faces out, but few days later and they have gone dark and look and feel damp again. The plasterboard on the ceiling will also be damp.

Any suggestions or thoughts about what or where the problem is? Are the bricks just shot? Are they just absorbing the rain water and its soaking through further down the chimney?

This is where my current thoughts are sitting. Is that a thing? What would a possible solution to this be? - rebuild the chimney with new bricks? Take down and add DPC above the roof line and build stack back on top?

Or could it be something else?

I’m at the point where I’m tempted to try anything to find the source of the issue. Even considering wrapping the chimney in plastic / clingfilm see if that reduces the damp… haha


Fire place probably was a traditional fire for much of the stone cottage life. But has had a log burner installed, with flue all the way to the top, with some form of insulation beads around the outside (maybe, unsure it was like that when moved in)



Thanks for any help, comments, suggestions, critics, etc etc. Just want to figure this out as its been a problem for a while.




Attached a bunch of images. Mostly of how it is currently. The one side of the roof was redone (probably when someone added a conservatory) as it has felt, but the other has the original lime plaster directly on the back of the tiles. This lime isn't present next to the chimney, as I had to remove it to remove the tiles to sort the leadwork out. I need to poke my head up in a storm to see if any water is coming up under the tiles, but I don't think this is likely the source as as mentioned the damp seems to be coming out of the bricks, rather than down their faces.

 

[Cubist]

Besides what you've already done I think you also need to address the poor condition of the pointing of the chimney stack. Some of the bricks also look to have fractured and, whilst they may not be loose, it would be impossible to seal them against driven rain; these need to be replaced. You should also take this opportunity to remove any Portland cements and replace it with a lime based mortar - this will help to obviate any differential movement that could, alongside the freeze/thaw cycle, be damaging the bricks.

Sadly, we have already seen some frosts os exterior lime mortar work, particularly up there, will not be advisable until the spring.

 

[Stevers]

Agree with Cubist that the pointing looks poor. Presumably there are two unvented flues each side of the live one - that won't be helpful either.

At some point I suspect that your chimney has been reduced in height and could benefit from being rebuilt to include a string course above the flashing and a corbelled top to help deflect the rain - quantity have a quality of its own for masonry. The lead work on the inner side looks a little undercooked to my eye, and the gods would be smiling on you if the mortared flaunch on the other side was doing much to keep the wet out.


In our case we inherited a stone stump with one pot on the left - much like you have now in brick. We rebuilt the chimney in blue brick (with cement lime mortar) to echo the original style of stone chimney on the right. All of our ten flues are either live with cowls, ventilated with elephants feet or have gas terminals. We already had the string course that is desirable above the flashing. It's likely that the chimney on the right was blown over and has been rebuilt using stone from the chimney that was taken down on the left with some new lighter Bath Stone insertions added during the rebuild. The lead flashing is in the style appropriate for random stone rather than stepped as for brick work.

It would be worthwhile taking a look at a few chimneys around you to get a better idea of what should be there.

 

[SH4RKY]

Agree with Cubist that the pointing looks poor. Presumably there are two unvented flues each side of the live one - that won't be helpful either.

At some point I suspect that your chimney has been reduced in height and could benefit from being rebuilt to include a string course above the flashing and a corbelled top to help deflect the rain - quantity have a quality of its own for masonry. The lead work on the inner side looks a little undercooked to my eye, and the gods would be smiling on you if the mortared flaunch on the other side was doing much to keep the wet out.

View attachment 14839
In our case we inherited a stone stump with one pot on the left - much like you have now in brick. We rebuilt the chimney in blue brick (with cement lime mortar) to echo the original style of stone chimney on the right. All of our ten flues are either live with cowls, ventilated with elephants feet or have gas terminals. We already had the string course that is desirable above the flashing. It's likely that the chimney on the right was blown over and has been rebuilt using stone from the chimney that was taken down on the left with some new lighter Bath Stone insertions added during the rebuild. The lead flashing is in the style appropriate for random stone rather than stepped as for brick work.

It would be worthwhile taking a look at a few chimneys around you to get a better idea of what should be there.

Ah, yes, now you mention it I think there was 3 flues when the cap was taken off. There is only one fire place though, so unsure why there would be 3? or is that normal? From memory, the flues were connected to each other, but obviously only the middle is now active with a log burner pipe to the top.

Yes, the mortar flaunch is not great. need to revisit that. it was moderately solid, so didn't want to mess with that too much at the time, but assume it was a patch up job to cover something else....

Is lime based mortar the recommended choice for chimneys, due to how exposed they are?

 

[Cubist]

Ah, yes, now you mention it I think there was 3 flues when the cap was taken off. There is only one fire place though, so unsure why there would be 3? or is that normal?

That would be very typical. Its likely that the others were used either in bedrooms and or a kitchen.

 

[SH4RKY]

Agree with Cubist that the pointing looks poor. Presumably there are two unvented flues each side of the live one - that won't be helpful either.

At some point I suspect that your chimney has been reduced in height and could benefit from being rebuilt to include a string course above the flashing and a corbelled top to help deflect the rain - quantity have a quality of its own for masonry. The lead work on the inner side looks a little undercooked to my eye, and the gods would be smiling on you if the mortared flaunch on the other side was doing much to keep the wet out.

In our case we inherited a stone stump with one pot on the left - much like you have now in brick. We rebuilt the chimney in blue brick (with cement lime mortar) to echo the original style of stone chimney on the right. All of our ten flues are either live with cowls, ventilated with elephants feet or have gas terminals. We already had the string course that is desirable above the flashing. It's likely that the chimney on the right was blown over and has been rebuilt using stone from the chimney that was taken down on the left with some new lighter Bath Stone insertions added during the rebuild. The lead flashing is in the style appropriate for random stone rather than stepped as for brick work.

It would be worthwhile taking a look at a few chimneys around you to get a better idea of what should be there.

Good shout Stevers. Not sure why I hadn't noticed it before.... but looking at chimneys in the local area, all have string courses and a corbelled top edge as drip protection. Will look to get this rectified as I suspect this is probably the primary reason water is able to soak into the bricks.

 

[Bash_Bash]

If you are going to take it all apart, then you might as well also fit a lead tray.