A plywood subfloor will bridge any minor waves in the existing floor and leveling compound would help too.
How to level old hardwood floors.
Alternatives to hardwood flooring.
The process of fixing both an out of level and an out of plane floor is simply known as leveling a floor.
Lay a long level downhill on the floor with one end of the level on the level part of the floor and the other end at the lowest point.
Raise the lower end of the level until the bubble is centered then measure the distance from the bottom of the level to the floor to find the depth of the dip.
Hardwood floor installers often use the term level when referring to subfloors when actually they are meaning the term flat while it s desirable to have a level floor most homes.
If you re replacing an old floor with a new one your first task will be to get rid of the outdated flooring material.
You will have to make sure your joists can handle the addition of considerably more weight from the plywood subfloor and any floor coverings.
The task of tearing out the old tiles.