Opps. Plaster mystery..

[Deleted member 265726]

Lol! Don't get rid of it mate, just get the bloke to have a look behind. Shoddy renderers hide multitudes of sins. Been there, got the t shirt and film rights sadly

God luck it all

 

[jj4091]

Might just be blocked gutter or down spout causing water to overflow the rear and into the cavity

 

[ree]

OP,
The render doesn't look right at all, the finish looks varied - & the outside corner is rounded off meaning no angle bead was used.
If you have such poor render, & a solid brick or stone wall then moisture could be penetrating through the wall onto the decorated surface?
There's also the condition of the chimney stack the bed room chimney breast, and its flue(s) to consider?
Does your chimney breast still exist on the ground floor?

 

[Rhys Whiteley]

Thanks Ree I'll get someone to have a proper look at it soon.

The chimney breast still exists. But has been closed up and hopefully capped at the top. But the damp doesn't seem to be from the chimney side. Just in the corner.

Thanks for the help! I've no idea what would look right or wrong tbf.

I will get someone to come out this week and have a look. I'll keep everyone updated

 

[Rhys Whiteley]

I'm hoping it'll just be this corner. Where I believe aerial wires are coming down under the render.