I'd first like to introduce myself and thank the good folks here for hosting this wealth of information, and making it freely available to everyone. I've been frantically reading through as many threads with a low enough jargon-density for me to understand what is going on; I've no formal training whatsoever in framing, but the design philosophy and craftsmanship really appeal to me as an aerospace engineer and amateur machinist. The plan is to learn as much as I can over the next several years as I narrow down the design & build up a war-chest, and by then hopefully have a good idea of what all I will be doing myself vs. hiring specialists/contractors for.

That out of the way, I'd like to pick ya'll's brains about an enclosure/framing concept that seems like it might have some merit. I've been trying to learn about enclosure methods, and just haven't been able to get excited about the daub-styles which seem to require a lot of maintenance & are somewhat limited as far as their design flexibility. Stick-built infill walls w/ plywood or SIPs just feel like cheating. So I looked into wood joinery-based systems, and found this diagram on a TFG thread;

Seemed very simple and straightforward, and seems to have served rather inclimate parts of Europe well enough. But it is ultimately a single layer of wood, to which daub or secondary paneling must be applied in order to get any degree of insulation or draft-seal (not to mention routing paths for conduit in a modern application)

So I wanted to see if there may be a way to adapt it to a double-wall layout;
-Similar to the Swiss style shown above that uses T&G slats stacked horizontally & set into vertical frame grooves to make a wall (Bohlenwand?)
-Instead of trying to use a super-thick timber to put two sets of grooves in to form an insulated cavity, use two parallel (smaller) timbers separated by an air-gap of several inches.
-The inner post carries the inner rafters of a double roof & the upper floor joists; the outer (taller) post carries the exterior rafters
-Columns are tied to eachother with several M&T cross ties along their length, so they function as a single load-bearing member as far as superstructure

Advantages;
-Seems to have all the benefits of a standard 'wall truss' arrangement, but without any thin spot in the insulation at the rafter/wall transition
-Wall can be made arbitrarily thick with about the same qty of timber
-Greatly reduced thermal bridging through the frames by way of conduction; a concern brought up for a super-thick post version
-The cross ties connecting the posts could be made to form a 'tunnel' for vertical wire/plumbing runs
-In my concept, the interior wall is horizontal slats from the ceiling down to about 3ft, where it changes to a system of vertical slats (think wainscotting) that cover horizontal wire/plumbing/ducting routes & can be easily removed/replaced. Above the transition, things are sealed enough that loose insulation can be used, but the actual accessible area uses foam blocks more resilient to infrequent tampering
-Allows for a thick double wall of excellent insulation value, while allowing for exposed timbers on both sides
-Will allow for wall/frame relative movement without loading up the wall boards
-Eliminates the need for plaster or paneling on both sides; can be simple exposed wood slats if desired & designed properly
-I would think is very draft-proof due to the pair of tortuous paths to get past the frames or between the slats
-Potentially the exterior panels could be easily removable/replaceable

Disadvantages;
-Since it relies on two sets of posts, the foundation footing needs to be wide enough to support both (& they'd both need to be tied to the slab/etc.)
-Not sure how the sill would be addressed to keep water from pooling there should water make it to the exterior wall
-High lower limit to how thin the wall buildup can be
-Windows/door frames may need to be an essentially standalone structure coming off the floor plate, since the inner/outer wall can probably shift relative to each other unacceptably. Not sure how different this is than standard practice, though.
-Cost, complexity, etc. which would be a little bit worse than 2X the single wall concept. The smaller timbers could help here, though
-I assume the frame spacing has to be closer than otherwise required for mere strength reasons, so the thin slat panels cannot warp enough to form significant gaps. Intermediate studs may still be required to stabilize the slats against bending/warping, but may allow the slats to get much thinner than the thick slabs traditionally used

I do not currently have a sketch in digital form, but I can scratch one up if my explanation is unclear. Thanks again for your thoughts

TCB