I am in the situation where I am converting a garage with a pitched cold roof above. However I’ve also removed the ‘external’ wall that separated the garage and kitchen.   I’m taking the opportunity to improve insulation with IWI in the garage and want to also improve airtightness. I’m happy with the floor-wall, wall-ceiling & wall-window details for VCL/airtightness layer with the garage itself. However I’m not sure what to do when I get to the original house.   e.g. Cru