Soft, crumbly plaster help!

[Melli]

Hiya, A few years ago I had some old skirting taken off in my lounge and the old plaster came off with them. The guy re filled the gap from floor to about 20 cm up with new plaster before attaching new skirting. There is one particular wall, an interior wall that seperates the lounge from the hallway/stairs that appears to have maybe not set right? As the stairs run up behind it I cant check that other side. The plaster has always been soft and crumbly all the way along just this one wall. Very fine, almost soft sand consistency falls off with ease but no large chunks or gaps. Wallpaper won't stick to it. There are no signs of damp, it doesn't feel wet, just very soft, no water lines, skirting and floor appears fine. All other parts that were done in the same room are fine with no issues, including 2 exterior walls. There are no issues any further up the wall, just the re done plaster. I'm selling my house and a survey has recommended

a damp survey so this is being arranged. There are no signs of damp, mould etc anywhere in the house! So I'm now in a panic that this wall is actually damp even though there are no other indicators. Google searches aren't providing any answers other than a possibility of "blown" or "bad mixing" I can't even find a photo of anything similar. Does anyone have any ideas of what could actually be happening? And if it is due to damp would there be other signs? Or is it just due to a bad batch of mixing and materials?

Need some tips or advice?

 

[Wayners]

Old property?
Maybe the mix wasn't as strong on that wall when done years ago.
If it's dry then only option is to get the plaster off and plaster.
You can use products like limelight as you should use gypsum on older properties.
Other option is to plasterboard over wall but stick on with foam so no bridging.
Old plaster crumbling can be from age so it's either make good or replace.
It's not always because of damp or other issue, just old

 

[Melli]

I'd say it was done approx 10 years ago. The house is maybe 90 years old. The rest of the walls are fine. Just that one all the way along. It was always a job I intended to get round to then never did. It's behind a large sofa so it just got forgotten about until now due to the survey and sale. I guess the damp survey will know for sure. I'm just worried that they will see it and assume damp when it may not be!

 

[Wayners]

House 90 years old.
Cavity walls?
if no cavity and gypsum plaster used that might be the problem.
Wait for survey