We have a house built in 1945 and an attached addition from 1970. The problem is we want to put in a pre-finished wood floor in the hallway but the floor is not level between the newer and older parts of the house. We've thought about blocking off the bedroom doors with wood and then putting floor leveling compound down but that would mean a drop off from the hallway to the bedrooms. I don't want to put new subfloor throughout the new house. Any thoughts out there on how to proceed?