Typically my stick frame home with poor quality doors runs in the 40% rh range in winter. I've thrown a meter into the framing and read about 8% in the dryest part of winter. Moisture inside the logs is going to disperse somewhat uniformly, I don't think you'll be able to meter any log or timber in a properly built home in the winter and see mc's in the 20%+ range necessary to support fungi.

Now today... EMC is closing in on that here.

I think a log wall is going to beat just about any cavity wall in terms of condensing room moisture inside the wall.

Piece en piece?