:confused: I'm looking for some suggestions on securing some of the oak hardwood floorboards that are bowed upwards and bouncy. The house is over 100 years old and there is no subfloor. The floorboards are in good shape (other than not being flat) and are about 3/4-1 " above the joist. This is only affecting an area of about 5' square and is more toward the center of the room which is 14' x 27'. The rest of the boards are pretty solid. Any suggestions? I don't want to pull up the whole floor to add a subfloor as this would raise it above the rest of the floors. The joists are exposed so bracing may be an option, but the boards are still elevated and there is no subfloor to secure them down to.

Are you sure it is the oak bowed up and not the joists sagging? Since the joists are exposed, it should be easy to put shims between the oak and the joist.

You could also attach the oak to the joists using hot dipped finish nails or "squeek stoppers" (Google it).

The joists are level, not sagging. The floorboards visibly bow upward and you can see the motion from below since there isn't a subfloor.

Your Going To Have To Face Nail The Boards Back Down, You Need To Hand Drive These Nails I Wouldn't Use A Nail Gun For This, Use Some 10 Penny Finish Nails, Predrill 2 In Each Board Per Joist That Should Pull It Back Down