Damp? by front door. Advice

[MrsFF]

Hi All

This is my first post and I am hoping you can help me out.

My father totally gutted this early 1900 property about 10 years ago for me. The walls are old stone with dot and dab plasterboard/plaster.
The property had new damp proof course throughout at the time.

Since I moved in this is the second time I have had this problem. To try fix it first time it appeared my father used a damp proof purple paint on the outside wall, inside wall, redone dpc in the area and redone the plaster boxing with foil backed plasterboard but the problem slowly came back!

As you can see from the pics there is a damp patch peeling the paint (feels cold and damp to touch) with white powdery mold. To me maybe its the join between the plasterboard sections?
There is no damp at the top or the bottom of the wall just the middle.

Anyone had any similar issues or any ideas to resolve this (preferably cheap).

Thanks in Advance

[Notch1]

Maybe the vertical DPC has been bridged and the plaster is touching the outside stonework .

Does the problem start from where the door frame meets the plaster?

[MrsFF]

Maybe the vertical DPC has been bridged and the plaster is touching the outside stonework .

Does the problem start from where the door frame meets the plaster?

Hi,
No it is on the other side of the wall and it doesn't touch the original stone that side?

[Dave54]

I wonder if it's penetrating damp or condensation caused by cold bridging somehow.

[MrsFF]

Thanks - what is bridging and do you know how I can fix it please?

[Dave54]

Cold or thermal bridging is generally caused by something heat conductive touching the back of the plasterboard. Could be wood, metal or the outer wall. It makes the pb cold (er) in that area, and condensation then forms on that area from the warm moist indoor atmosphere.
A fix could include removing the reason for the cold bridge, which obviously means stripping the pb. Also possibly ventilating the area where the problem is, or if the kitchen or bathroom opens onto the space, keeping the doors shut and any extractors running would remove the source of moist air.

[MrsFF]

From the front door its an open area leading upstairs and to the landing so it is ventilated (not near the bathroom or kitchen).

There is a radiator by the front door with piping (can slightly see it in first pic) - would that be a cause do you think? There is nothing behind the plasterboard.

Thanks

[Dave54]

TBH it's difficult to do more than suggest possible causes on a forum.
If there's nothing behind the pb apart from dot and dab, it could well be the adhesive dabs themselves that are causing cold bridging. If it is cold bridging of course.
I did read somewhere that a large percentage of cases of "rising" or "penetrating" damp were actually caused by condensation though, which would tend to agree with my own experience.
The areas of damp do look very localised as well.
Windy, wet and cold weather will make the outer wall colder as well, which increase any condensation problems.

All assuming that there is nowhere obvious that water is getting through from the outside. Bad pointing or gaps around the door frame etc.

[MrsFF]

Thank you so much. It does get worse in bad weather.
At least I know what I'm dealing with now.

Very helpful

[wes56]

a photo of the outside wall and a photo of that corner of the room.
to see whats happeng you willhave to remove the plaserboard on bothsides of the corner, the cornerbead might be rusty as well