Darryl wrote:
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.

I had a similar situation once and how I solved it was cut a 2X4 to the
desired height from the floor joist above to the top of the sleeper then
used that to determine shims and nail length needed to level the floor that
would be applied on top of the sleeper. Your example may need wedges cut
instead of shims as I don't know what the slope is but use the 2X4 method to
see what you need then determine which way to go about it.

Rich