Damp nightmare!

[Alisca]

Hoping for Mumsnet wisdom!
1900ish terrace with damp in the living room.
It’s the wall with the chimney that adjoins next door (so not an external wall)
The house had no original DPC. One was ‘installed’ many years ago but has failed.
We had major renovations done to the room, so had the plaster stripped off, left to dry (which it seemed to, albeit this was in June this year when the weather was dry and warm).
Airbrick put into the external wall as the old one had been plaster boarded over.
Old gas fire taken out and a load of builders rubble removed from behind it.
The roof has been checked and although we will be getting a new roof in the next year the roofing guy didn’t think the roof was a major issue or likely to be causing the damp.
Wall has recently been re plastered and is now struggling to dry.
Floor is concrete.
Having spoken to the neighbours other houses on the street have damp issues although don’t seem to be as major as mine.
Any ideas where I go from here?

My daughter had that in rented flat and it was the chimney/flashing

Bumping, as suspect house I’m moving into bad similar behind some wallpaper…

*has

Did you replaster with lime plaster or modern gypsum stuff? Is the plaster straight onto the wall or is it plasterboarded first? Has anyone put a plastic membrane in? Is there a gap behind the skirting boards and wall or does the plaster go all the way down to the floor?

There was thick wallpaper on the wall when we moved in, hence not realising that we had such a big issue until we removed the wallpaper (been on the house three years but only just taken off the wallpaper).

I think it’s just modern plaster, over plasterboard. There is no membrane.
There is definitely a gap between the plaster and the floor - there wasn’t a gap originally but when we had the work done a gap was created.

Looks to me like it is coming up through the concrete, which can happen. If so then a membrane can be applied that stops it. If it were the chimney I would expect signs of it higher up the walls. I'm no expert though, so I'd say call in a damp expert and get it sorted. The plaster should then dry out over time.

We have had a ‘damp expert’ come to look but they just wanted to install another DPC, which we are a bit concerned about doing given that the previous one appears to have failed.

What is underneath the floor? That seems like a good place to investigate.

You could have an old pipe leaking under the concrete.

Is there any way to be sure if it is a leaking pipe without having to dig up the concrete floor?

Can you get a surveyor specialising in damp who uses thermal imaging? They will advise the source.

As per above, get a damp surveyor in to give you a report. They have no financial interest in selling you anything. Sounds like you had one of those damp experts who just want to install more dpc regardless which 50/50 will fix your issue. Looks like rising damp so you need to trace the source. If solid concrete floor then likely tracking up from there. I agree with roofer in that it is unlikely the roof / water ingressing down the chimney.

Thanks all. When we bought the house 3 years ago we had an independent surveyor (specialising in damp) in as our initial basic homebuyers report stated there was damp and recommended we get a specialist.
The specialist said that damp was present in the living room but it was likely caused by condensation and lack of ventilation and didn’t present any major issues. Obviously this now looks to be incorrect.
It’s very difficult to know who to trust and where to go for advice without feeling like you’re chucking money down the drain.