One of the books I read was called "A round Indiana". The 2 barns we have here were both built about the same time. I'm planning on using 3/4 CDX plywood for my plates, and ridge beam. I'm going to make a steam box for the sidewall girts, which will be 1x.The ridge beams in round barns were made in segments of a circle. The 2 barns I have seen the ridge beams were made up of sections of 2x8s. I was on a DHIA tour at the time and the one farm had 2 round barns. The owner told the group that the barns were built from kits in 1920. His grandfather had them built. Sadly both barns are gone now.