The mystery of the damp wall

[Cubist]

I'm familiar with that technique but not seen it in practice. It should as I understand it eliminate the possibility of water ingress from the chimney except perhaps at it very highest levels BUT....

....Going back to the matter of smoke appearing in your loft space - part of the gable wall of your loft is also the rear wall of the chimney breast in your neighbours house and if the mortar pointing was in a poor condition this would explain the source of the smoke. If that pointing was not properly repaired at the time or was perhaps merely coated with a layer of render then this might provide a path via which rainwater entering the chimney could find its way to your wall below.

If you can find no obvious faults in the masonry in the loft space you have little choice but to get on with your internal repairs and hope that the root problem has been resolved.

 

[Quaintcottage]

Thank you Cubist . You are correct , the following photo is of the party wall in the loft. The neighbour’s chimney will be the other side of this wall.



The photo quality is poor , but in the distance you can see render on the party wall. I often wondered why that wall in the loft was partially rendered , but your explanation makes sense. Maybe they rendered it before next door had their flue lined.

I have never smelt smoke in the loft; fortunately I have 6 vents in my roof to allow outdoor air to circulate in the loft.

There is one point I cannot get my head around , or visualise. My cottage was built onto an existing cottage . If I understand correctly, the builders must have knocked into my neighbours gable wall to access their chimney flue and connected it to my now defunct fireplace .

In which case , were both properties fireplaces , ultimately using the same flue that exited via the chimney stack on my neighbour’s roof?

I cannot see how they could have knocked into my neighbour’s gable wall and created a second flue, inside my neighbour’s existing chimney .

I have tried Google images to try and find an image that explains this .

I will though , lime plaster the damp damaged wall, and keep an eye on it throughout the year .

Thank you for your help