Damp patch

[Betdo]

I live in a simidetatched house on taking the wallpaper off in the front room , found a black mould .
Starting from ground floor about 2 feet high.Above up staires bedroom as well.
I have checked the loft wall, roof, outside guttering and downpipe .No sigh of damage etc.
Now a a loss to where to start.

 

[Chri5]

Might the gutter be blocked with natures debris and overflowing in heavy rain?

What's the overall condition of the outside surface, if brick might the point be failing?

Is there a down pipe near the damp areas?

 

[Bosswhite]

What is the heating like, it could be a cold spot

 

[Betdo]

Gutter clear, brickwork no problems. I have notice there is no air brick at the front of the property. Try and put in a airbrick at the weekend.To see it will do any good, fingers crosed