We finally have a usable second floor. This afternoon, Mike and I finished laying the subfloor layers upstairs in the shop. The 2”-thick vintage barn flooring that we had reserved for this has a beautiful underside which will be seen as the ceiling of the first floor but the top side was quite chewed up (presumably from animal hooves). Not only were there deep gouges and fibers that were ready to jab you but the wear was so extreme that hard knots were full thickness but the area around them was worn down to 1” thick in some areas.
Because we appreciate the charm of an old worn floor, our initial thought was to sand the daylights out of the coarse side. But first we laid a few in place and, because of a few very thin and spongy areas, it became immediately clear that these boards would not work on their own. (Besides, who in their right mind wants to spend days and days with a palm sander and 40 grit?)
So, we decided these old boards needed another layer. There was one problem though: the wear was so extreme that there was no way we would be able to lay new flat boards on top of them. Rather than run them through a planer (also long and miserable work), we opted to overlay these wild barn boards with tongue and groove OSB to bridge the low spots (with the help of shims).
Shims first, then tar paper (to darken any gaps on the underside), then OSB. Sheet goods are no fun to work with but the OSB required minimal cutting and went down fast. During this process, we also ran wiring around the perimeter of the upstairs and fabricated a trap door for future hoisting of large objects to the second floor.
It’s amazing how rigid the floor feels now. Tongue and groove was definitely the way to go in this application. All that’s left is to fore plane some wide pine top floor and nail it down with cut nails.