Yes, you're right any humor bypassed me. No, I'm not suggesting that you put all your plumbing into one single wall; I'm trying to help you understand what goes into building so you can make your ideas more efficient. It's smart to consolidate your plumb lines. Maybe illustrations will help: This is a very basic 5x8 bathroom (40 sf) with all its plumbing lined up in one wall -- this, of course, is a simplification -- no one's suggesting that you downsize to a minimal bathroom: Now here's a 5x8 bathroom (again, 40 sf) with the plumbing divided into two walls: Both bathrooms include the very same fixtures, and neither is more "liveable" than the other; however, the second one will be more expensive because water will have to run through multiple walls to service the fixtures. Because the second bath has more plumb lines, the second bath is more likely to suffer a leak and need expensive repairs in the future. Most interior walls are 4" thick, but walls that contain water must be 6-8" thick, so the second bathroom will lose a few inches of usable space. If you're talking about one bathroom, maybe it doesn't matter ... but when you're doing the same thing across the whole house, it's adding up to real space. If one of the above baths fits into your plan better (scoots in next to the available space next to the closet, allows your entrance to be more spacious, or whatever), then you might sacrifice the bathroom's efficiency to get a larger closet, or to make your entrance work out more conveniently -- but that's not what's happening in your plan. Your plumbing is just scattered around without regard to practicality; it can be consolidated without sacrificing "liveability". If you REALLY want to be efficient, you can line up two rooms to consolidate water. For example, a bathroom might "back up against" a laundry room -- both rooms can be served with water with only one wall being 6-8" -- plumbing efficiency at its best: In contrast, look at your master bath layout: You'll be running water through three different walls to accommodate your water needs, and it's not necessary. By turning the toilet and the shower both against the exterior wall, you can have them share the plumbing. Numerous other options exist as well. Maybe you're thinking that lining things up will end up too simple or too dull. Here's my master bath floorplan -- note that the tub, sink and shower all "line up" on one wall ... and the washer is just through the wall in the next room. The toilet is in a separate wall to prevent the room from becoming too long and narrow -- but at the heart of it, this is just the super-simple bathroom from above ... stretched out to add a few extras. It's efficient and cost-effective.I hope this helps you understand the concept of consolidating plumbing, and I hope it helps you understand that efficiency is not the enemy of "liveability". Again, good luck on your project, and that's all I have to say about it.

Your research has allowed you to think to out of the box but it has also led you away from your goal of a comfortable maintainable dwelling. Cement is one ingredient of concrete. When individual concrete piers are used in place of a continuous perimeter concrete or CMU foundation, large above-grade beams must be placed between the tops of the piers to support the structure and that creates an open space under the house that is difficult to maintain and the floor is difficult to insulate. It is also usually forbidden for dwellings where modern building codes are in effect. It is possible to pour a slab on grade but in a cold climate the edges of the slab must be have walls under the edges to below the front line. In general this building method is most appropriate for utility buildings in locations where animals are not likely to cause problems (beavers love plywood) or winters are very mild and the soil is stable. In any case, what would you build the walls and roof with and would you rely on the buried posts for lateral bracing? My guess is you will get less house for more money if you intend to finish it well. There is no reason to think post and beam framing will give you larger open spaces. the reason to use it is if you like the look of exposed beams and an occasional free-standing post. Personally, I like to avoid posts in a house and have gone to a lot of trouble to remove a few of them in P&B houses I have renovated. IC's advice is good; find a local supplier of prepackaged post & beam houses or a good design-builder or architect. It will take you years to earn all you need to know to design and build a house. This is a before photo of a post & beam Yankee Barn house from the 60's: After

I don't know anything about "Gert" construction, but in normal homes the wiring is inside the stud cavities, stapled to the studs or (if added after construction) fished through. If there is space behind your wall surface, that's where your wiring will run. If not, it will have to be installed on the exposed surfaces of the walls. In that case it should have mechanical protection. Wiremold is one well established system for surface wiring. Maybe I'm misunderstanding you, but from what you've posted, it seems that you're building an office larger than some apartments, you're installing an 11+ KW PV system, you already have an EV (presumably a Tesla), and you're talking about buying a Tesla Cybertruck. None of this comes cheaply. It's just a bit surprising to hear of a person who obviously has ample financial resources worrying about saving a few thousand dollars on the wiring for a new building. An experienced professional licensed electrician will know good ways to wire your office. I suggest that you let him do the job. In your place, I probably wouldn't mess with the trenching, either.

Will your parents need the office room as well or is this a room where you could use a closet to put the laundry in or could you enlarge the bathroom to have side by side laundry. For aging having the machines on a pedestal is helpful as the up/down gets harder as you age with a stacked washer/dryer. However, in Europe having the washer in the kitchen isn't uncommon and then to hang the laundry without even having a dryer and has been done by young and old for a long time. Washer/dryer stacks are also common in the bathroom there. But the last two are definitely not friendly for someone with mobility issues. I see no issue with locating the machines in the bathroom, but if you can spare some space to put them side by side and on a platform it would greatly improve the usage from an aging perspective. I'm guessing though that with them living near you that this is something you could easily help with if need be. This article have lots of other info: https://www.thespruce.com/design-laundry-room-aging-in-place-2146701