If your flooring isn’t level, the first course of action is to check what’s happening in the subflooring system. I recently got a call from a client complaining that the floor was uneven. To rectify the problem, the flooring guy had given the OSB panels a heavy sanding.
However, upon inspection we found that the two beams below were not exactly the same depth which was causing the I-joists that were sitting on the beams to be at different heights and that was the cause of the uneven floor – not the panels. When there is a problem with the floor you should first check what’s below before starting to do any work or calling a supplier. In this case the issue could have been corrected before any costs (sanding) were incurred. Always check to be sure I-joists are square and aligned before installing sub-flooring panels.