and as Karen provided the information, the R value isn't much at all...about half what a house would be built to today. Back in the day our ancestors didn't need to keep the inside very warm.....tough people,them..and they had a virtually unlimited supply of fire wood.

Why didn't you just google "R value of wood logs"? It's from .71 per inch for most hardwoods to 1.41 per inch for most softwoods, according to http://www.energy.gov