Following on from my Foundation post,   I want to get the detailing correct on the windows, this is spurred on further by reading this post      My build will be with PolySteel ICF, 50mm EWI, Board on Board vertical cladding.  UPVC windows.   I'm thinking of using a stub sill on the UPVC window and then an Aluminium over sill.    Using the sketch by @Babak in the above post, I have come up with the following   Questions:  1: I'm thinking I need to