Help, pease. Damp patches on internal wall.

[Puzzling]

Hi,
Hope someone can help with this. I'm getting patchess and roughness on an internal wall. It only affects one part of the wall.

A recent picture is attached. Since then, I've stripped the paint, reskimmed, primed with Zinsser BIN and repainted. Sadly, the staining/roughness at the bottom has come back, as has a similarly stained patch about four feet above the skirting. The bits in the middle (stained in the photo) now seem OK.

Skirting is perfectly dry. Paint at the stained/rough bits leaves a mark on the fingertips, i.e. a bit chalkly.

Any ideas? I guessed not rising damp (dry skirting and four feet up patch). Condensation?

Do the symptoms ring any bells with anyone?

Thanks in advance View media item 68097

 

[Chri5]

What's on the other sides of the wall?

Might there be a pipe in the wall? Could someone have at one time used the area as a riser for hw, cw or ch feeds either on or behind plaster.

So consider what is above that area as well as behind both parts of the wall you pictured.

 

[Puzzling]

Thanks, Chri5.

I'm not sure what's immediately behind the wall you see. It's hollow, by the sound of it, with a cross section around a foot square. Cupboard behind and there's no sign of any marks on the two sides visible from inside the cupboard. Above is a bathroom, but the pipes from there are at the other side of the room.

I guess it's possible a ch pipe runs down the inside, as the boiler is on the floor above.

I guess it looks like penetrating damp, to you, given the questions? Could that cause the odd pattern of marks? I was rather hoping it might all be down to my lack of decorating skill, requiring (I guess) a much easier and cheaper fix.
Cheers

 

[Chri5]

Find a mate with a metal detector and check? (Although if newish the pipes might be plastic).

If there is any accessible pipe work check for running leaks where the leak is follow a pipe run downward. It might not be such, but if you have used industry finishes and the stain is repeating it sort of suggests something is making is wet. It's not condensation.