Damp Exterior Wall

[Ninja_Mouse]

I live in an end-terrace and the exterior wall, that is the end of the terrace, is damp from from halfway up to the very top. All the paint on the outside where it is damp is peeling off and, inside the house, the landing window has damp above it. Can anyone tell me why this might be the case?

I've been doing some work in my loft to add floorboards and a couple of lights and I can see more clearly in there now. The loft is dry except for the beams holding the roof tiles up seem to be a bit damp, from where it holds up the tiles to the centre. There is also what appears to be a vent at the top in the wall but this seems to be completely blocked up. It's so blocked up it almost looks like it is on purpose but I assume that it should be clear. The eaves seem to be clear.

Any help on what is causing this damp will be greatly appreciated!

Thanks,
Farran

[welsh brickie]

for the damp to penitrate there has to be some crack in the render externally.Also open the vent up as its in the loft the vent will dry any moisture and increase airflow.