I am putting together drawings for a posh outbuilding / garage, with a concrete slab and timber frame walls. This will be a posh outbuilding first and maybe a garage in the future.   My initial idea for for the floor junction detail is below, this has 100mm of celotex which maybe overkill in the floor, on a 150mm concrete slab.   The issue is that i want to maximize head room in the posh outbuilding, so i could either reduce the thickness of the insulation or i could bring th