Not sure how old the original barn is, but it is older than sawmill technology. All of the original logs/beams were hand hewn on two faces. No saw marks, just axe marks. The roof had failed, and many of the original logs were rotten. I sawed out some 6" thick beams to replace the back wall of this old barn. In the pic, all 7 of the beams in the back wall (leftmost wall in the pic) were sawn from my blue pine. The owner put 3 steel wool pads in a gallon of white vinegar and treated the bottom four beams. This gave the them an old weathered appearance. In the pic, the original wall is the rightmost wall. The new wall is the leftmost one. The match on the bottom four beams is incredibly good.
The sides and back shed walls were done with my blue pine live edge slabs sawn at 1 1/8" thick. In this pic, they have not been treated yet with the steel wool and vinegar solution.
This is a really cool project. The owner has a second barn to restore, even in worse shape. The progress so far looks very nice.