They are quite

The next step is to lay vapor barrier on top of the heat insulator. This is necessary to prevent moisture from the apartment.

At the end, it is necessary to cover the floor with boards again. If old boards have no flaws and damage, then they are quite suitable for further operation. If the boards were turned into dust in places, and when walking, the creaks were noticed, then the flooring is recommended to be replaced. Typically, experts use OSB sheets or a dense plywood, but if the means allow, then of course the use of new, even and soaked in a special solution (protection against parasites and mold) of the boards will be the perfect option.