Possible Attic Damp

[Sipherlucian]

Hi folks, recently noticed dark areas appearing on the left and right side of a vaulted roof, you can clearly see the stud on both sides, at the top. behind both walls are closed off attic spaces, the eaves are not covered so theres still ventilation on both sides.
prior ro rennovation a few years ago the attic space was one larger span that included whats now the vaulted section, never any damp issues in it.

the closed off attic sections are not accessible at the moment so before i cut through to see what the issue is im gonna hazzard a guess that what im seeing here is the heat from the hallway (stove in room downstairs) coming up and hitting off the plasterboard and theres very likely no insulation in the stud wall so the cold of the attic and the heat of the hall are probably forming condensation on the back of the boards, would that seem correct?.

Assume the solution then would be to insulate those sections of wall after i dry the plaster out.

 

[blup]

If the damp is caused by moisture from within the house, insulating the pb will make it more difficult to escape and the damp will worsen. The outline o the stud in the first pic (left hand side) suggests it could be external ingress, maybe related to the velux. Removing the pb is a practical way to confirm the likely source(s). Ventilation is key.

 

[^woody^]

That's typical of pattern staining due to thermal bridging from poor design or construction. Not "damp" as such but is related to air humidity/ condensation, it's more an aesthetic issue rather than a damp issue - but it could become one if it progresses and gets worse. It's not a given that it will worsen but it will be forever visual.

Yes, the remedy is to insulate across the inner face of whole wall to remove the thermal bridging.

 

[Sipherlucian]

That's typical of pattern staining due to thermal bridging from poor design or construction. Not "damp" as such but is related to air humidity/ condensation, it's more an aesthetic issue rather than a damp issue - but it could become one if it progresses and gets worse. It's not a given that it will worsen but it will be forever visual.

Yes, the remedy is to insulate across the inner face of whole wall to remove the thermal bridging.

Thanks Woody appreciate it!