Damp that’s so bad it’s running down the wall?!

[Shadowboy]

We have an odd damp patch that wasn’t significant for months but in the last week it’s become a really big problem because the wall now has water droplet running down it.
I’m lost for what’s causing it- it’s an internal wall (although now looks to be spreading to the external wall) the other side of the wall is exposed brick (fireplace) and that feels dry.

There’s no pipes in this part of the house, and the room above has no damp. In fact there is no damp anywhere else in the house- just here.

I painted 6 months ago and didn’t notice anything when I painted but now it’s flaking off the wall. What do I do to solve this?

How old is this part of your house?

If the other side of the damp internal wall is a brick fireplace, then does that mean there's a chimney in between?

The logical assumption would be that there's water coming down the chimney? If that's the case then it would be relatively easy to fix by putting a cap or cowl on the top of the chimney.

Yeah, leak in the chimney seems like the obvious answer. There’s salt coming out of the bricks which suggests they are damp.

Could be cold air coming down and chilling that wall, then causing internal condensation between brick and finish wall. A kind of cold bridging effect. Do you have the flue closed and a flue blocker in the fireplace like a Sheep Plug?
www.chimneysheep.co.uk/

Barring that, how is roof flashing around chimney? Sometimes water trickles in around poor flashing between roof and chimney and runs down chimney wall between finish wall and brick...causing damp spots.

Are your chimneys capped off? That would be the first thing I would check (if they’re not in use of course)!

The chimney is in use with a wood burner, so it’s is sort of capped, it has a cement cap to one side then a steel cover over the flue that lets the smoke out. The steel cover has a mesh to stop birds from getting in etc but twig water is getting down it, surely it would travel down the flue?

@CavernousScream

Yeah, leak in the chimney seems like the obvious answer. There’s salt coming out of the bricks which suggests they are damp.

@CavernousScream that’s paint that I couldn’t quite strip off the bricks. There were three layers black, white and green. I did what I could but lots of patches remain sadly.

Also the chimney was very badly repointed by previous owner in modern cement rather than lime so not sure if that’s the issue?

We have the same.
Its our chimney. It needs coming down and rebuilt. It doesn't help we have a very old granite and sandstone house so it's become quite porous .
I'd get the roof checked around the chimney stack.

We have a log burner and yes the rain will come down.

Modern cement will be the reason salt is coming out. I solved the damp problem in my house just by having the chimney wall repointed in lime.

Loads of salt and water came out at first and then it completely stopped.

Other than that the issue is the chimney stack and flashing at the top.

@FlamingGoat I know the roof and flashing are ok as it came up in the survey as bad so we then had had the whole house re roofed in May and new flashing has been sorted. It was a large job at great cost.

If it’s coming in the chimney it would need to be the mortar in the stack and/or the top?

Also the chimney was very badly repointed by previous owner in modern cement rather than lime so not sure if that’s the issue?

Yes, this can cause damp issues. It should have been repointed with correct lime mortar as @AnnaMagnani mentioned in pp.

www.heritage-house.org/damp-and-condensation/types-of-damp-what-have-i-got/damp-problems-caused-by-cement-pointing-of-brick-or-stone.html