Damp mark on ceiling (Ed.)

[Keve]

Is anyone able to tell me what this is, what is causing it and how can I fix it. It is on the ceiling of our bedroom which is an extension. Wanting to decorate any tips on what to use to prevent it returning, thanks in advance

 

[Wayners]

Looks like condensation.
You need insulation above including any tight spaces around the edges.
Then you need to address the moisture problem.


As for ceiling wash over.
Stain block
Emulsion
.

 

[foxhole]

Have you checked roof condition ?
Flat roof?