Wall is covered in grey spots

[DougQuaid0]

Bedroom wall is covered in grey spots, its on the outside facing wall. I though it was mould but it won't come off (used mould remover) Pic attached

 

[motorbiking]

Is it in the corner - it looks like damp / mould. yes it can be hard to shift.

 

[DougQuaid0]

Is it in the corner - it looks like damp / mould. yes it can be hard to shift.

Thanks.
Its across most of the wall, but not beneath and pictures.

If its mould, would a covering of Zinsser, followed by paint do the trick?

 

[motorbiking]

I've used 3% / 10 vol Hydrogen peroxide. You just need to ventilate to stop it coming back.

 

[Koolpc]

Its linked to condensation / lack of ventilation.