The bedroom in my house has deep recessed windows and I have noticed that the walls in the recess are suffering from damp. Could it be lack of ventilation or could it be that the seal around the double glazed window which does not seem to fit properly is causing this. I also have a small extension that was built approx 10 years ago (prior to me buying the house). There is a patio window in this extension and the rendering below this has blown. I am going to pull all this off and re render the wall but I have noticed that the side of the extension and the wall above the rendering is very damp. Could it be the poor rendering that is causing the side wall to also be damp. The extension is only about 4ft on the end of the existing lounge. I think that there is a damp course in the extension although I am not sure