Hi, I’m looking for any information you gents can provide regarding the sealing of new units over a lead flashing. My elderly neighbours have had new windows fitted in an upstairs flat. The two rooms with small bays, have decorative lead flashing installed directly below the window. D3spite the internal joints being sealed, the external gap between the window and the flashing is in the order of 15mm and, the shims used to level the window units are clearly visible on close inspection. They have complained of a draught, owing from the lower edge of the new window units. Should this gap between the flashing and the window unit be sealed and, if so, what with?