Damp Proofing

Mould (possibly?) appearing on wallpaper but not on the wall

Anonymous user 28/02/2024 - 3.06 PM

There are dark patches on the wallpaper on my landing, most just under the coving, all on INTERNAL walls. None of them are damp to the touch. I've been into the loft: I can't see or smell any damp, when I peel back a bit of the paper the wall is clean underneath. I'm assuming it must be mould but am not sure. There is also dark discolouration to the underside of the loft insulation near where the worst patches are. The house is 24 yrs old, very warm and well-insulated.Any ideas welcome!