Damp through external wall

[psarinuk]

Hello,

I hope I've posted in the correct forum.

I've recently acquired a house that was wallpapered everywhere by the previous owner.
I've taken off the wallpaper in one of bedrooms and found the wall plastered underneath.
So I put the filler in where necessary, made it smooth, coved and painted it white.

However, recently I've seen that the exterior walls just under the coving are developing a bit of damp/ mould. I also remember that the wall paper in those areas was falling off like anything. I can trace this in every room above windows and along top edges of external walls. This has started happening since winter has set in.

There is no damp or wetness in the loft and the windows are double glazed (look new as well).

Could someone please throw light on what's happening? Do I need to treat my exterior walls? Please let me know if you need any pics.
Thanks.

 

[cherryred]

Without seeing it this sounds like that common winter problem condensation.
Its always going to be much worse in the winter and is simply warm air containing moisture meeting cold walls whose temperature is below dewpoint result condensation.
Worse in older houses without a cavity.
Removing moist air at source eg cooker hood fan and bathroom fan and exhausting outside also keeping rooms warm which will raise temperature of walls to reduce condensation. Also opening windows.

 

[JohnD]

//www.diynot.com/wiki/building:condensation_in_houses