Hello Collin:
Seen your post concerning the oldest structure in the USA. I think that might be alittle hard to nail down truthfully, and be able to back up the information with facts without someone coming along and denouncing it. Maybe just talking about an "old structure" or a documented old frame, be it a house, barn, driveshed, or mill might be a safer approach.
I reproduced period structures for a number of years, and it is exceedingly hard to truly date them POSITIVELY.
If I can be of any help to you and your cause, I may be able to draw on my many years of research and hands on reproduction of some of the earliest buildings framed by the United Empire Loyalists who emigrated to Upper Canada beginning in 1784 near the end of the American War Of Independence
Richard