Jim,

Yes, it does mean 'plank wall'

The Bohlenwand is common in alpine and sub-alpine regions, and takes on a number of forms. The alpine method is generally to have horizontal boards.

From what I know of the Scandinavian practice, I think you are right. There was an old Viking age and early medieval technique that was very similar, only placing the planks vertically. There are many fine examples of this technique that have survived into the present day, the Norwegian Stave Churches. The Urnes Stave Church in particular, since it dates back to about 1050, or the very end of the Viking age. This technique is called Stavverk, or 'stave work'. It has a timber frame with planking caught in grooves cut into the sills, plates, and posts.

This technique is probably how the better houses and farms were built in forested areas populated by Norsemen, with the poorer houses having walls filled with waddle and daub.

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as for nailing instead of grooves...

I had considered this idea, and came up with only 1 solution that seems suitable, which is the first nail a piece of wood to the posts, and the nail the planks to this piece of wood. I do not think it would work to nail the planks directly to the posts, as they would barely be supported that way.

This solution is not without its problems however. The extra wood takes up insulation space, and creates a few more seams for water to collect and cause damage.

In addition, the groove does more than just hold the planks in place. It also stops drafts, and hides movement. I would suspect that if the planks were nailed to the edges of the posts, expansion and contraction would cause the nails to pull out over time. With the grooves, the wood is all allowed to move up and down and side to side as much as it wants.

For most projects, there is no need for timbers exposed inside and out. The double plank wall is designed for this particular situation. Today in America frames are typically exposed only on the inside, in Europe in the past frames were often exposed only on the outside. It is also common to have frames completely covered inside and out (which is the simplest to enclose)

Personally I think having 8" of timber jutting into your living space is a bit silly. (oops, did I say that out loud?) and I much prefer the look of a barely exposed timber, which is either flush with the inside wall or sticks past at most 1". The bohlenwand is really the ideal method of accomplishing this, the planking could simply be a means of supporting drywall or plaster, or form an attractive wood interior wall.

If you don't want timbers exposed on the outside, then this system lends its self readily to numerous insulating techniques. Just have an inside plank wall, and enclose the outside wall in one of many methods.

and to your last comment, look at Icelandic turf houses, and you tell me!