A plywood subfloor will bridge any minor waves in the existing floor and leveling compound would help too.
How to level out uneven floors.
Installing flooring on an uneven concrete can cause buckling and loose boards after the installation.
Common issues that turn out into uneven floors.
When complete this will be a spacer that bridges the gap between the old floor and the new level surface.
If the area is very large use a long straight 2 in 4 in 5 1 cm 10 2 cm board and set your level on top of it.
Between this support system stretch floor joists that also support your floors.
Adjust the strip as needed.
How to level uneven floors.
You will have to make sure your joists can handle the addition of considerably more weight from the plywood subfloor and any floor coverings.
Over time concrete floors can settle unevenly or become uneven due to cracking and moisture.
Position the leveling strip on the floor and see if the top edge of the strip checks out as level.
There is a system of columns which supports the entire weight of your house.
Whether you want to refinish an uneven basement floor or replace or add new flooring on top of an existing concrete floor somewhere in your home you most likely will need to level the concrete floor.
If the floor is uneven lift up the board until it is level so you ll know how much flooring compound you ll need to even it out.
On the top side of the floor another fix it idea to lay down new hardwood over the existing floor.
Floors are rarely perfectly level.