Hi, I have been experiencing really bad condensation on my dormer window. I can feel a draught so I know I need to tear up the plasterboard and the interior window board to foam up any gaps. I took of the window board and noticed a bit of mould underneath. I don't know if there is water ingress or if its just the condensation causing it. There is a gap between the window frame and what looks like something I can only describe as a floor plate (grey/black colour) the window frame sits on? Is water getting through on that may be? Do I need to seal this gap up? I think silicone rather than expanding foam for this gap. Any insight would be greatly appreciated.