Wet Spot in plaster

Bloody annoying this is, council re boarded and skimmed wall.

When applying mist coat noticed vertical stain say 2 inches long about 5mm thick.


Council cut square about half a metre square to investigate, they told me bone dry behind there and plasterer claimed it had been a little bit of plaster that had not dried out.They patched it up,I waited a week for skim to dry however a little suspicious of this horizontal stain slightly smaller this time at bottom edge of new skim .

Ive applied mist coat and its still there, Ive informed council and they are reluctant do do anything about it this time, what the hell is it??

I fear this little stain may get bigger, I want to get this room decorated but fear will still have to go back into wall again to investigate, is this just the plaster or is it water leaking from somewhere???

The pic attached is first stain, will photograph new one tomorrow as I said new one is vertical and slightly smaller.

 

thanks for the reply phil but just want it sorted before i push on, why is this happening, is it that water cant dry out of the plaster sometimes , its a small patch about half a metre by half a metre and its right at the edge of the plaster,ive never experienced this before, two lines in two different locations but in plaster

 

yes that sounds feasible, they should have used pva, i left it a week it looked dry and like the last time a 2 inch stain appears, its almost as if the water cant completely get out.

im gonna take a pic today and send it to council AGAIN, im going to carry on painting, if this doe snot dis appear then will have to cut in again..they said would get building surveyor in this time..i have 3 weeks before i move in and this stain is really ******* me off......why is it happening..had three rooms skimmed..no probs and this patch just leaves a stain????

 

i havent mate but im starting to wonder if its the existing stud..first the vertical stain now a horizontal one.i take on board what you are saying about stain block but what if it is water behind there, the council said it isnt but how do i know they are not cost cutting again...i cant bring myself to block it i want to see whats behind there......a plasterer friend has suggested cutting out the offending area and filling it..

 

Astra its a council flat, I have to be careful, If I start delving and unerarth something big, they will probs make me pay....want them to investigate again , this time I will be present.

I moved in three months ago and stripped walls, revealing appalling walls...they had to repair some of them, this one is their work..