To ensure superior soundproofing, we recently poured liquid self-levelling concrete on the floors.  When the liquid cement hardens, the floor is absolutely smooth and level, and the cement provides substantial soundproofing between the condos.

The cement is on average 4cm thick.  It hardens in about three hours.  Ready to apply the finished flooring on top.

The first photo shows the pouring of the cement onto the floor.  Note the installers wear special boots with studs on them so they can walk though the wet cement with ease.  The second photo shows the new smooth floor, later that same day.

Pouring the floors. Nice Boots !

Finished Floor. Smooth As Can Be. And Soundproof Too !