Hey fellas, I'm hoping someone can shed some light on this for me. Next spring, I'm looking to build a new shop/shouse on some undeveloped acreage. Thinking 60x80 or 60x100 slab on grade with 2x6 walls, 20x40 sectioned off for temporary living quarters. The deal is, I plan to build an ICF house in a few years when finances allow, also slab on grade, on the same parcel and would like to have a small partial basement under both for the mechanical rooms. I know it's a sin here but this will be Geothermal in both buildings with a solar array on the shop roof, both of which have far too many credits to overlook and will put me money ahead in 8 years. When the house goes up, I intend to build an ICF tunnel connecting the two because I hate winter and like secret rooms. I've talked to 3 different local concrete companies and they all think I'm nuts (I probably am) and that it's impossible, but I don't see any reason why one couldn't do what I want as long as there's a frost footing around the perimeter under the slab so it's monolithic. Shouldn't be any different than an attached garage when the house has a basement, right? They move together in bad frost upheaval with a proper frost wall, why couldn't a monolithic slab? I've spent days on Google trying to find some information and have had zero luck. Anyone ever done such a thing?