Question about subfloor materials
I am trying to figure out if the floor I am seeing the bottom of is a "real" floor, or a subfloor. I can see the underside of it in my basement, and I can also see the sides of it where the opening for the basement door (which is a trap door in the floor) is. This (sub)floor is tongue and groove, and the boards are about 4 1/4" in width. It would have been installed right around 1947.
I don't know anything about subfloors, which is why I'm asking: were/are tongue and groove boards used for subfloors? It would seem to me that a subfloor, which would have been covered up and been nailed through/glued onto anyway, would have been made of something cheaper, less "fancy" and/or less labor intensive than tongue and groove boards. Can anyone enlighten me?