Please forgive me if this is question has been asked to death. I've done some searches and I couldn't find an related posts. There is a a significant drop at one end of my hallway of about 18mm. We're having a new front door fitted and the installers need to know what the height of the new floor will be. We've chosen our flooring but I'm not sure what the best practice is for leveling floorboards. Has anyone had experience in this area? What's the normal practice for leveling a traditional timber floor?