I've got a uPVC window that is leaking around the frame when it rains. One bottom corner gets damp whenever it rains. We've just had the room interior gutted and replastered, so I've just noticed this. I checked the exterior silicon seal right up the side, the top & bottom of the window. It was in a poor condition so I replaced it all. I am confident that it is now water tight. The damp patch dried up (once it stopped raining!), and all looked OK ... until it rained again! I'm at a loss now as to where the water is getting in. We've got solid walls (1920's house) with a render on, which looks sound. Could it be getting in through the frame, and not draining out properly (i.e. via the cill) but running to the side maybe? Any tips as to potential problem areas to check gratefully received!!!