help / advice on persistent damp-problem on chimney-breast.

[belfast_boy]

We have had a problem with a wet / damp patch in an upstairs room.
Several avenues have been pursued in the past. But it has stayed.

The damp problem is not very bad, but it does mean the wall feels slightly damp/sticky to the touch and wallpaper will not hold etc..

We recently had the loft over it insulated (a hatch was created, so we can inspect on the loft over it). We are also havin the chimney repointed, so this seems a good time to investigate new ideas on possible causes / solutions.

The damp patch has been for years in this room.

I have indicated on this picture what the extent of the patch is.

The wallpaper that used to be on that wall/chimney breast had turned black. It was removed to put plastic and new plaster on that side. In the hope the problem would be gone. This did not solve it.

We are waiting to wallpaper it and turn the room into he new kids bedroom.

The loft over the room has been opened to install new insulation.

The bricks over the damp patch feel a wee bit wet, but not as damp as they do in the room below. The mortar is all very dry, crumbly etc. The bricks over the damp patch sem slightly darker and a bit stained.

Over the loft is the roof which is being re-re-repointed.

I keep wondering where the water may be coming from. We also had the chimney capped a couple of years ago.

One suspect could be the area where the slates connect to the chimney.

Or in more detail:

Any good ideas on the most likely causes, how to find/investigate, or what to do would be very much appreciated. (maybe 1 lie in the loft and another hose the chimney? or something like that). Unless it is already clear what the cause is from these pictures.

Thanks for your thoughts and advice.

Kind regards

 

[noseall]

hygroscopic salts

solution: take it back to brick, s.b.r. slurry coat then replaster.

 

[belfast_boy]

hygroscopic salts

solution: take it back to brick, s.b.r. slurry coat then replaster.

We did try taking it back to brick. Unfortunately that was not enough.

Look forward to your idea of hygroscopic salts. I do not understand what you mean. Do you think they are the cause, or should they be apoplied as a solution?

Sorry for my dumb question(s).

 

[Deluks]

That leadwork could be a bit neater. When was that done?

 

[joe-90]

Does your boiler vent up the chimney? The waste gases contain large amounts of water vapour that condenses as it reaches the upper part of the chimney. Go around a neighbourhood that has terraced houses and look at the walls of the end terrace and you'll see what I mean.

 

[belfast_boy]

Does your boiler vent up the chimney? The waste gases contain large amounts of water vapour that condenses as it reaches the upper part of the chimney. Go around a neighbourhood that has terraced houses and look at the walls of the end terrace and you'll see what I mean.

Thanks. but no. There are 4 vnts in the chimney. Only the one in the front of the house was used for a firepace in the front room. The rest are capped.

 

[belfast_boy]

That leadwork could be a bit neater. When was that done?

It was done quite a while ago.

Since taking the plasterwork down to the brick, and replastering over plastic foil did not eliminate the problem our attentions turned back to the possibility of it actually leaking through. The problem rmeains: where can it be?

That is why the pictures of the lead and loft were included.

Could the humidity come through just over where we re-plastered?

Thanks.