I am helping a friend remodel his recently purchased home(circa 1903) in the Johnstown/state college area of PA. We started by gutting the house, upon gutting I noticed the frame work is nothing I recognize? The exterior walls appear to be three layers of planks, each layer going in the opposite direction? The interior walls are all 1x12 planks going from floor to ceiling? Being an advanced handyman, and working in the trades in the New England area I thought I had seen it all. My friend wants me to just start framing, I dont feel comfortable doing so, while not knowing if the house is sturdy enough to hold all the extra weight. Has anyone seen a home built like this before? PLEASE HELP!

Thank you, Tom