I am installing pre-finished 2 and 1/4 inch tongue and groove oak flooring in a second story bedroom. The house is 33 years old and I have found that in the middle of the room, the floor is out of flat. The out of flat area is about 7ft across the joists by about 6ft along the joists, roughly a 7ft by 6ft area. How can I fix this before I put the floor down. I would prefer not to take up the subloor as I believe it is glued down

Sand high spots; fill low spots with 30 lb. felt or thin plywood or both.

Thanks Gary for the info. What would I put down first, the felt or the thin plywood as I probably would need to use both??

AL:

Try this link for ideas--

http://www.hardwoodinstaller.com/hardwo ... r-prep.htm