Terrace chimney wall damp

[Mozandroz]

Hi
First time posting so apologies if I don’t explain this very well. Terraced house party wall in the kitchen was newly plastered. Within a few months a big wet patch appeared at the top. This got worse the more it rained. Think this has been a chimney breast wall as directly above is a chimney wall (unused and blocked by previous owner) and then the attic which was converted a few years ago. There appears to be no wet on the attic wall, a smaller amount on the middle floor and then an awful lot on the ground floor. Had the chimney pots covered to fix this. He checked flashing and did some pointing too. After the rain this week the wet patch has returned even worse than before. Next door is split into flats. There is a small damp patch on the middle floor of next door. The top floor flat of next door will not help. There are no pipes or radiators on these walls so thinking this can be ruled out. Any help is greatly appreciated.

 

[Mozandroz]

 

[JohnD]

how old is the house, and what shape is the roof? photos may help

It does look like it may be coming down the chimney, but a popular modern building technique is dot and dab, where there is a void behind the plastrboard, and there is a chance water from a leak might be running down the gap.

sometimes, roof drains and gutters take odd routes through loft conversions to make their way to a downpipe.

i think you are going to have to make holes into the flues in the chimneybreast and take a look. There will be a separate flue for each of the fireplaces there used to be, probably one per floor, but you may smell and see damp with your first hole.

 

[Mozandroz]

Thank you for taking time to reply. The house is late 1800s and the roof is an apex roof. I can try and find some pics on my phone otherwise I can add tomorrow