Hi Dan and Everyone;
An earthfast barn! That makes three...I have heard there are still two of thse in Saint Mary's City, MD.
Board roofs were common on all types of buildings including houses, though probably most common on outbuildings. I have seen some good photos of these, but I could not find one to post. The boards were sometimes set with the edges on a thin batten or protruding nail to force a U shape and then the top edges covered with a batten. Even if they were not forced into a U shape, they curled that way naturally with the sun beating down on the top surfaces. There could also have been two layers of boards without battens.
I was just reading about the Stanley-Lake barn which is an ancient (pre 1718?) barn in Topsfield, MA on the Ipswitch River. It, like the Giddings-Low barn in Essex, MA (before 1702) have common purlin roofs and may have been "single boarded and battened" as is a reference to "The 1667 Nelson barn in Rowley...". Most of this information is from the linked article by Robert Blair St. George.
http://departments.umw.edu/hipr/www/resource/pva1stgeorge.pdfJim
