The actual living experience/architecture of barndos tends to be subpar - limiting your building footprint to a big metal box heavy on interior volume really impacts where you can put windows and doors. Most of the ones I have seen tend to be dark and awkward. Now I am sure there are some really well done examples (which people will post) but if you are doing this for cost reasons, that is unlikely to be you.
I didn't get into this in my previous reply, but you are absolutely correct. It is certainly
possible to build a barndo type structure that is as comfortable and pleasant as a traditional house, but it will be comparatively difficult and expensive to do so.
There is a reason that homes are built the way they are. Things like exterior walls, natural light, human scale spaces, and truly residential vibes/flow/finishes are the things that make most people feel at home and comfortable in a structure. Even people with the budgets to build whatever they want tend to end up with something that feels like a traditional house, albeit an enormous one.
An individual homeowner could reasonably decide that they don't care about these things, or even that they prefer the sort of living space that results from a barndo layout. However, they should be realistic about this being a very uncommon perspective and that if they (or their inheritors) ever sell the place most potential buyers will not be interested.
Personally, I don't want to go through all the expense and effort of building a new place just to wind up with a white elephant - especially when a more comfortable/functional option is readily available for about the same cost.
As far as inspections go , so long as everything has a engineer's stamp on it you would think building it would be uneventful?
This varies widely with your specific zoning/building regs, but generally the answer is "No, an engineer's stamp is not sufficient for what you are trying to do".
Consider that a structure that can be
built is different from one that can legally be
occupied as a residence.
Example: I have a prefab shed in my back yard, the drawing plans are stamped by engineers from several states including the one where I reside. Despite this, I cannot live in my shed because it lacks the features required of a habitable structure. Even though everybody agrees that it is structurally sound and won't fall down, it would still need things like plumbing, insulation, and multiple means of emergency egress before somebody could sleep there.
I encourage you to really research and understand the codes that apply where you are planning to build; there are very few habitable areas where there are truly no rules around this sort of thing.
I very much want my house to be absolutely bulletproof from a permitting/zoning/code perspective, IMO the stakes are too high to just build a noncompliant (or even arguably noncompliant) structure and hope nobody ever notices.