Whether you can put composite floor composite floor?
Smoothness is not required very flat, with a flat, straight point of wood, at least 2 meters long sticks above, placed on the ground, to see the flatness, if the difference is not enough, you can
A new floor is installed on the old floor. As the elevation rises, it is likely to cause insufficient clearance under the door. Or other aspects of decorative items modified.
If the room before the baseboard, it also needs to take the thickness of composite floor skirting the overall elevation at least more than late buy. (or simply removed to do or directly shut lines)
The original floor, must ensure the firmness, loosening, shedding to day after lay hidden.