As I understand it, you have to build like an 18-inch thick wall to conform to their architectural guidelines. This means that each wall has to actually be two walls; i.e. it comes down to building a house within a house.
So, the first thing I’d ask your contractors is if they understand simply framing the place will require twice the “typical” amount of wood.
There are, of course, higher end finishes required on pretty much everything thing else starting with windows and doors and then working inward, so the costs just continue to add up, but really, just start with the 18-inch walls and see if the story changes.
