I'm putting in a wooden floor over my basement smooth-concrete floor.
6mil plastic, then treated 2x4 sleepers Hilti-nailed to the concrete,
then 3/4 osb panels over that. Half the floor is done, and it has gone
well so far. I'm adding the floor for insulation purposes, and so that
I can use different floor coverings in different rooms.
However, a 20x20 section of the floor slopes down to an unused sump
pit. How do I level the floor to compensate for this slope? Do I
first nail the 2x4s to the sloping floor (a very slight slope) and then
somehow level the osb panels, or do I make the concrete level first
before attaching the 2x4s?
And if I level the panels somehow, how do I do it in a way that would
prevent the floor from flexing? If the panel doesn't rest securely on
the sleepers (for example, if simple shims are used, leaving gaps
between the sleeper & panel), the final floor will bounce.