We've got a 300mm cavity wall being built on our extension (cavity contains 50mm air and 50mm Ecotherm). We want to install a UPVC sliding sash window (probably quickslide) in a checked reveal to match the existing house, which also has cast concrete sills like the ones in this picture:
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anyone have any idea for how the detail where the sill and the window meet works? I presume with a checked reveal that the sill needs to be somewhat deeper than normal so that the bottom of the window sits upon it, but we are worried about damp proofing, cavity closing and insulation, I can't find any information on the web about it, and our architect has neglected this corner for some reason.