Damp but from where

[swampydrill]

Hi
I have attached some photos of an issue that seems to be getting worse. You will see that underneath the coving in the lounge there is a damp patch, this has been getting worse over the past 5 months, coincided around same time as had windows changed. We have a porch fitted and the damp area seems to be parallel with the right hand side of the porch. I have had a look and there is no damage to tiles (it would leak through roof in porch), flashing looks in good nick. I have pulled back carpets upstairs, removed floorboards and checked central heating pipes and they are all ok, plus not had heating on yet. I really don't know what the issue could be, any ideas. The house itself is brick/breeze block, no plasterboard.

 

[^woody^]

The wall above the porch roof looks darker/damper than the rest. If there is water getting in from the roof/gutters above or via defective pointing, and no cavity tray was fitted when the porch was added, then that's a potental cause.