Water/Damp on external walls

[NIKMANS]

I have a re-occuring problem each winter once the wet weather starts with wet and damp patches in the bedroom and also living room.
Since last winter i have removed the wallpaper and painted with damp proof pain once it had dried out. I have also purchased a de-humidifier and ensure a small window is open in all rooms at all times.
I woke this morning to find a damp patch in the top corner of the room and what i would describe as tears of water across the top of the outer wall beneath the coving.
Could this be a problem other than condensation?

[welsh brickie]

No sounds like its penitrating through from either the roof or render outside

[eddylyons]

check the roof for leaks and also check the pointing on the outside, it might need re pointing. i had to use a damp proof membrane to stop damp in my house. its old and needed insulating anyway. so i used dpm on wall then 2x1 batterns with celotex inbetween and then plasterboarded over the top. then had it plastered and then painted...its been fine since but costs a few quid.