Another damp on chimney breast query

[Esbm2015]

We've just removed the wallpaper in the living room of our new flat and discovered damp at the top of the chimney breast.

On removing the wallpaper it felt wet and sticky and the wall is discoloured as you can see on the picture.

The rest of the chimney breast feels dry and seems fine so it's just that patch.

It's an internal wall and there is a woodburner in the fireplace although not sure how often that was used by the previous owner.

The living room is on the second floor of our flat. Directly above is the loft.

Anyone any ideas of the cause of the damp and what we should do next? I'm not sure who we need to get in for a trustworthy quote and to get it fixed.

We're looking to paint over or wallpaper again as soon as possible so would welcome any advice.

Just to add the damp and discolouration is only the semicircle right at the top of the chimney breast near the ceiling.

The other bits are the remaining wallpaper we need to get off :-)

Check the flashing where the base of the chimney stack meets the roof and see if you can see any issues with the chimney stack from outside - you might have to go across the street, etc.

Get a good roofer to have a look. It may be the lead but much more lightly to be the flaunching.

Thanks for all the responses, will definitely get a roofer in to take a look.

Looking online there is lots about hygroscopic salts?

We have this (to a lesser extent but also affects ceiling) and was told it was a salt leaching thing affected by the wall being replastered with modern plaster which ideally should all come off and be redone with something breathable. We've ignored it so far, so would be interested in what your outcome is.

When I had this it was the flashing round the chimney which needed repairing.

Watching with interest. We have 2 damp patches with our chimney. One where it meets ceiling and one next to the mantelpiece 3 ft down on the other side. Have new roof and new flashing but hasn't fixed problem. Loft above the damp ceiling is dry and no sign of damage,......

I've also read about hydrophorbic salts causing the issue but do not know what the remedy would be for that? Has anyone ever come across it/had it treated? I think it involves stripping back to the bricks and replastering with special plaster?

Well we've so far had two roofers come round. Both have said we should put caps on the chimneys and have said we need the flashing and flaunching redone.
They also want to water seal the chimney and put a new gutter on at back of the house.
Price sounds quite reasonable - £1,400 so think we may go for this and hope it sorts the issue.

i have this in my bedroom on the chimney breast. The opinion of two damp specialists seem to be that it is salts, and nothing can be done unless we knocked the chimney breast down (external wall, not likely). We have had a mesh/membrane put between the wall and some plasterboard that should solve the problem for the next 25 years or so, which is fine, as we will probably have down sized by then.

We have salt penetration on one of our chimney breasts. The previous owner spent a lot of money on the external chimney, the lead has been replaced and the chimney sprayed with a waterproof sealant......we still have salt penetration!! We have been told that the plaster needs stripping back, a mesh put in and the wall replastered. We were quoted about £800 4 years ago. The builder said it wasn't essential work, just cosmetic, so we haven't done it.